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HomeTech Articles > 911 Carrera Engine Starting Troubleshooting

Guest Technical Article:

911 Carrera Engine
Starting Troubleshooting

Doug Suds
djsuds@ix.netcom.com

Here’s a few useful 84-89 carrera tidbits that others sent me while going through my recent diagnosis.

No-start Diagnosis (84-89 Carrera)

1. Remove a spark plug wire and insert a test plug into the wire, place it next to the engine, have someone crank the engine and look for a spark (or remove one of the plugs and do the same). I didn’t have a second person to crank the ignition, so I clamped vice grips on my key, ran a wire from the end of the vice grips through the door handle (with the door open). This allowed me to pull the wire and crank the ignition while standing at the back of the car looking at the spark. Crude, but it works. You could, of course, get a remote starting tool to achieve the same, and there are also special long coil wires available that allow you to see the spark while sitting in the driver’s seat (just a long wire from the coil that has a spark plug socket on the end).

2. Remove the air cleaner cover and air filter, and spray some fuel into the intake. You will have to hold open the little "door" inside there with something. If it starts briefy then dies you probably have a fuel problem.

3. You can jumper a hot wire to the fuel pump and listen to it whir to prove that it’s working. Run a short wire from the fuel pump fuse (#6) to an adjascent fuse (#5 or 7) at the bottom of the fuse terminal, the pump should whir. BTW my car didn’t have the fuse info on the fuse cover (I think the old one broke), so Jim Bauman gave me his info from his ‘86 (#21 is closest to the front of the car):

  • 1. window winder, seat heater, sun roof
  • 2. booster fan, seat adjusters
  • 3. headlamp washers, electric cabriolet top
  • 4. clock, radio, interior lights
  • 5. locking system
  • 6. fuel pump
  • 7. brake light, cruise control
  • 8. electric mirror, heating control
  • 9. fresh air blower, cig lighter, rear window defrost
  • 10. wipers
  • 11. rear blinkers, back up light
  • 12. front left blinker
  • 13. front right blinker
  • 14. left high beam
  • 15. right high beam
  • 16. left dim
  • 17. right dim
  • 18. parking left
  • 19. parking right
  • 20. fog lamp switch, rear fog lamps
  • 21. foglights

4. If the fuel pump whirs (when jumpered), try starting the car this way (this overrides the DME control of the fuel pump). If it runs, it probably indicates some kind of DME problem (the DME is not sending power to the fuel pump). If still doesn’t run, it’s probably not a DME problem. Thanks to Jim Bauman for sharing this tip.

5. If it is a DME problem, replace the DME relay, which sends power to the fuel pump. This is another one of those parts that is known to be flaky. The relay is under the driver’s seat next to the DME computer. It’s highly recommended to carry a spare DME relay anyways (a $40 part), so go ahead and get an extra just in case.

6. If the relay doesn’t fix it, it could be the DME computer itself, faulty sensors (flysheel speed and position), or faulty grounds. Try disconnecting the DME computer and cleaning the contacts.

7. Check all ground connections (brown wires) for corrosion.  Disconnect them, clean them, and replace. Check especially the ground points in the engine compartment. There’s one on the manifold pipes, and another on the left side of the engine compartment behind the fuel filter. There is another one on the bottom of the car around the transmission.

8. Check all fuses for corrosion. Remove each fuse and replace.  All DME-related fuses are up front, but there are three fuses under the plastic cover at the left rear side of the engine compartment.

9. If you have one available, swap in a known working DME computer from a 911 friend. Be careful that you have the right production year and part number because there are differences in the pin mappings.

11. If the DME is okay, you can listen to the injectors with a stethoscope, if they click, then power is getting to the injectors.

12. At this point you probably want to have a shop check the fuel pressure and flow rate in the system. This requires special tools. In my intermittent problem, this test unveiled a faulty fuel pressure regulator ($75 part).

13. Finally, Chuck H sent me some detailed info on the DME system. I didn’t get this far (thankfully), but if you want to get down to the nitty gritty, here’s the DME connections. Note that NTC stands for Negative Temp Coefficeint sender (meaning as temp goes up, resistance goes down).

 

  • 1 coil ground (1)
  • 2 micro switch (throttle, idle), closure to ground at idle position
  • 3 micro switch (throttle, wot + throttle valve) test connection b, closure to ground at wot
  • 4 t54, starter active, +12 volts while cranking engine
  • 5 gnd
  • 6 gnd, air flow sensor, ntc I
  • 7 air flow sensor +
  • 8 speed sensor +
         0.6 to 1.6 kohms between pins 8 and 27
  • 9 air flow sensor -
  • 10 plug for exhaust data (ground)
  • 11 t54, speedo
  • 12 test connection a
  • 13 ntc II
         1.4 to 3.6kohms at 70oF
         160 to 210ohms at 212oF
  • 14 t55, injector control signal
  • 15 t55, injector control signal
  • 16 gnd
  • 17 gnd
  • 18 +12v
  • 19 gnd
  • 20 control signal, dme relay
  • 21 t54, goes to speedo
  • 22 air flow sensor, ntc I +
  • 23 .75ohm connection to pins 5, 25, 26, 8 & 27
  • 24 oxygen sensor
  • 25 ref mark sensor +
         0.6 to 1.6 kohms between pins 25 and 26
  • 26 ref mark sensor -
  • 27 speed sensor -
  • 28 altitude sensor
  • 29 a/c compressor clutch ‘on’
  • 30
  • 31
  • 32
  • 33 idle speed positioner +
  • 34 idle speed positioner -
  • 35 +12v

pinout, looking at the DME connector, NOT the DME...

+----------------------------------+ | 35 19 | +--+ - - - - - - - - - - - - - - - - -+--+ | 18 1 | -----------------------------------------+

Cheers,
Doug (87 Carrera Targa)

PS. I sincerely hope you are reading this out of interest (not necessity) and I suggest that you get in that 911 and DRIVE!

Comments and Suggestions:
chaosComments: hi, I replaced ECU because the car actually stopped and would not start again.I fitted the spare ECU after checking that fuel pump wasn't working I did try DME as well.The spare ECU then and is hunting between 500 and 2000 rev.It looks like the old ecu fails to run the fuel pump, DME is Ok.Could I run the fuel pump on a switch with the original ECU without causing damage? Thanks
April 20, 2014
 Followup from the Pelican Staff: I would advise against a switch. Does the replacement ECU part number match your old one? The idle may be hunting due to software differences. - Nick at Pelican Parts  
chaosComments: sorry ment 500 to 2000 revs
April 19, 2014
 Followup from the Pelican Staff: Got it, thanks. - Nick at Pelican Parts  
chaosComments: Hi all, My 1985 3.2 is giving me3 a headache..Car broke down, I replaced ECU with an old one that did work fine in the past but now the car hunts vary badly from 500revs to 200revs.|Also if I earth out that ECU the car again fails to start.Tried having original ECU with no earth still failed to start did fire the old petrol left in system .
briefly...Help!!!!
April 19, 2014
 Followup from the Pelican Staff: What made you replace the ECU? If fuel pressure and spark ok? - Nick at Pelican Parts  
Tom BComments: I have a 85 911 3.2, with 36,000 original miles. Car ran perfect last fall. Has to have some surgery so the car has set for 6 months now car turns over great, but will not crank. Have no fire. Any idea what is causing the no fire problem. I just replaced the DME
April 5, 2014
 Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
Big JackComments: Gary, 1992 Carrera. After sitting several months had no start cond. Normal testing found no fuel being delivered. Fuel pump would not spin, only had a "thud" when energized. Ordered and installed new Bosch pump and DME relay. Bench tested old pump and verified it was seized up. Installed new pump, engine started and ran perfect. Road test OK put additional fuel in tank and parked for 2 weeks. Have exact cond again, same no start same "thud" from f/pump again. OUCH. Where now? Can fuel gal like diesel and seize pump. Thanks for any help
March 28, 2014
 Followup from the Pelican Staff: Pumps don't usually seize. They refuse to start due to a bad commutator bar. The hit gets the pump to move, starting it back up. You may have a faulty pump. - Nick at Pelican Parts  
yayo_ayalaComments: Gary, before you have the problem bypass fuse 6; you should hear a fuel pump. After an hour, when the car is not running, bypass once again the fuse 6 if you hear the pump, try starting the car.

If that is your problem you have an issue with the relay or the DME.

I just did it and found that the relay was faulty.
January 29, 2014
 Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
GaryComments: I have a porsche 911 sc 1983 . Runs good when I drive it for one hour and shut it off for one hour it will not start for 4or5 cranks. Where can I start.
January 23, 2014
 Followup from the Pelican Staff: See yaya's reply:

Gary, before you have the problem bypass fuse 6; you should hear a fuel pump. After an hour, when the car is not running, bypass once again the fuse 6 if you hear the pump, try starting the car. If that is your problem you have an issue with the relay or the DME. I just did it and found that the relay was faulty.- Nick at Pelican Parts
 
BillComments: Hi, I have a 1995 911 993 convertible 3.6 injection. It has not been started for nearly a year, in hospital after major surgery, the battery is charged it turns over but does not start. The fuel is low but does still have juice in the tank. There is a knocking/tapping noise from the engine as it attempts to start. It has only done 30 k.
November 23, 2013
 Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.

One possibility is that the valve lifters may have drained down. Charge the battery fully, then make sure the lifters become filled with oil by cranking the engine. Do not crank for more than 45 seconds at a time--you can burn out the starter motor. Allow it to cool down a few minutes, then crank again. - Nick at Pelican Parts
 
aqtlibraComments: I have a 1999 Porsche Carrera Coupe after i disconnected/reconnected the cable from the battery terminal. i can no longer insert the key in the ignition switch. is that normal because i don't have the radio code. meaning the ignition switch locked.
October 13, 2013
 Followup from the Pelican Staff: This is an odd one. If you look into the lock cylinder, does it look blocked? - Nick at Pelican Parts  
bomberoKevComments: Terrific article, thank you. One question: if jumpering the fuel pump does not eliminate a problem when the car is *running*, can I rule out the DME system as the source of the problem? I am trying to diagnose rev-hunting and power loss and very occasional non-starts in my 1985 Carrera. When I jumper the fuel pump, the rev-hunting continues. If as the article says the jumper "overrides the DME control of the fuel pump", then can I conclude that the DME system is not the source of the problem? Or am I making a logical leap too far? Thank you!
October 9, 2013
 Followup from the Pelican Staff: Correct, if you suspected fuel pump control as the issue and you remove the DME from the control side, it cannot be the issue with the fuel pump. - Nick at Pelican Parts  
mr c..Comments: A have a 1983 911 sc and my problem is it will start when the engine is cold ...start right up but after I drive it for a little bit it takes too many cranks to start again..
October 7, 2013
 Followup from the Pelican Staff: I would perform a fuel delivery system test when the problem is not present and when it is present. Check fuel pressure, volume and quality. - Nick at Pelican Parts  
PhilComments: Thanks Nick for your response, it does provide me with comfort that this is normal, so does this mean that I dont need to wait for Oil levels to finish it's cycle.... I have seen the counter display 58 mins, sitting in the car for this amount of time and not being able to start my journy seems crazy.

Thanks

phil.
September 16, 2013
 Followup from the Pelican Staff: If it is asking you to wait 58 minutes, there has to be an issue. The sensor could be failing. - Nick at Pelican Parts  
Philoo68Comments: hi
i have a no start problem on my 85 carrera, european version without cat, i can't fix despite the points you've mentioned :
DME Relay new
Fuel Pump working
Fuel Pressure = 5 bars : OK
Both sensors new
all fuses new
ignition ok, tested with a spare spark plug as indicated below

actually i didn't replace the temperature sensor, i don't think the trouble come from here.
don't know how to check the DME computer. i doesnt sound good at all:-
i want to check the 14 pin plug on the left side of the engine, does anyone know which colour matches which number?
any other advice?
thanks
September 9, 2013
 Followup from the Pelican Staff: If your engine doesn't start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.

if you have spark, but lack fuel injector pulse, you could have a faulty DME.

I'd grab a repair manual, it will have the wiring for your specific vehicle. I'd hate to misidentify a wire and give you bad data. - Nick at Pelican Parts
 
PhilComments: I have a 911 Carrera S on a 55 plate and each time I turn the ignition I wait 6 seconds to ensure oil levels are correct as per the digital counter on the dash before fully starting the car. If I turn of the car and then start again the time for oil levels counts back from all different times, it could 10 mins could 1 hour, it all depends how long I have left between re starting the engine. Is this correct, seems odd if it is?

Hope someone can help.

Thanks

Phil.
September 6, 2013
 Followup from the Pelican Staff: This is normal as it checks each time you start or cycle the key. - Nick at Pelican Parts  
wackoComments: is there any way i can make reversing sensors lauder 911 carrera 2007
August 8, 2013
 Followup from the Pelican Staff: No - Kerry at Pelican Parts  
thedbuttonComments: I have an '88 3.2. Recently, it has a 'non start' problem turns over fine, but won't start when the car is on a slight grade with the nose elevated i.e. driveway. As soon as the car is level, it starts right up. Also, the fuel pump seems to be noisier. Any thoughts?
July 21, 2013
 Followup from the Pelican Staff: Could be an issue with the fuel pump. I would recreate the symptom, then check fuel pressure volume and quality. - Nick at Pelican Parts  
jarvaitComments: I have a 911 Carrera 3.2 1986. The car start very well when the engine is cold. When the engine is warm and i turn off the engine, if i want to start again, the engine dont want to start. I have to wait 10 minutes and after the engine start.
July 9, 2013
 Followup from the Pelican Staff: When its hot put your foot on the accelerator and floor it. Does the engine start now? You may have leaking injectors. - Nick at Pelican Parts  
awayneComments: Thanks Nick so if there is no power to the pots on the coil what could the problem be then? Thanks awayne
July 5, 2013
 Followup from the Pelican Staff: I don't know what the "pots on the coil" are. I assume you mean starter solenoid. Large terminal should always have battery power and small terminal should have power with key in crank position. If you tap power to the smaller terminal the vehicle should crank. Try jumping the starter relay - Nick at Pelican Parts  
awayneComments: Hi I have a 1981 porsche 911sc, drove it home had been sitting for a long time then shut off now wont start turns over good, has fuel,should there be power on the coil posts? the bosch cdi is making winning noise? coil is full of oil no leaks, doesnt seem to have spark?
July 4, 2013
 Followup from the Pelican Staff: There should be power to the coil when the key is on or when the engine is cranking. - Nick at Pelican Parts  
FredComments: I have a 1984 911 drove fine, parked for an hour, then would turn over but not start. I bought a DME from you and replaced. HAd done this about a year before and car ran fine. New DME didn't help this time. Tried to jump the fuel pump but got no whine. Do I need to replace the fuel pump? Can I get to the pump myself and replace?
April 14, 2013
 Followup from the Pelican Staff: If you manually activated the pump with power and ground and there is no fuel pressure, the pump may be faulty. Check that there is fuel in the tank. If so, you need a pump. You can replace it yourself, not a bad job. Just be careful not to spill fuel or get any on yourself. Clamp off the feed line to the pump to prevent the tank from leaking.- Nick at Pelican Parts  
LindyComments: Have an 86 911..Last summer it wouldnt start..I replaced the DME relay and has run very well untill 2 days ago..I again replaced the Dme relay and it started but would not restart for several hours...Should I replace the fuel pump relay?? Also cruse control guit..Could that be the curz control relay...Thanks
April 7, 2013
 Followup from the Pelican Staff: If your engine doesn't start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.

I would avoid replacing parts until you have an idea of what is missing from the scenario. - Nick at Pelican Parts
 
larrymComments: i had a weird anomaly - started, died - turned out that 3 of the injectors were stuck - took a few days of troubleshooting & testing to find this

see http://forums.pelicanparts.com/porsche-911-technical-forum/738792-3-2-starts-dies-immediately-all-tests-good.html#post7326923


March 13, 2013
 Followup from the Pelican Staff: Thanks for the info and taking the time to share this. We appreciate it. - Nick at Pelican Parts  
SlojeepsterComments: I have a 89 911, While driving after the car gets fully warmed up it will intermittently briefly "stall" then restart. It will do this sometimes once and sometimes many quick on-off episodes. I replaced the DME relay with no change.
March 2, 2013
 Followup from the Pelican Staff: You'll need to determine what is making it stall. If you keep your foot on the accelerator, does the engine still stall? If not, it could be the idle control circuit. If it does, you'll have to determine if you are losing spark or fuel. - Nick at Pelican Parts  
terrlynnComments: [ have a 1984 it sounds like it wants to start but wont turn over
February 14, 2013
 Followup from the Pelican Staff:
If your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose. - Nick at Pelican Parts
 
ZabComments: I have a 1988 Carreras , at high speed while in the 5th gear , RPM moves erratically, it seems fine when i am in the lower gears .. My car has 145000 miles. Is this a big issue?
January 3, 2013
 Followup from the Pelican Staff: is the clutch slipping or is the engine surging when the problem occurs? Either way I would look into it, this could be an unsafe situation. - Nick at Pelican Parts  
ThutoComments: I have 1988 3.2 carrera sometimes the engine miss fires, when i check the spark plugs i find traces of oil on the 2nd and 6th spark plug, but when I replace the spark plugs the engine runs smoothly again i dont know what causes the this problem how can i resolve this challenge
December 11, 2012
 Followup from the Pelican Staff: If it is isolated to only those two cylinders, you could have worn guides or pistons rings. Some tear down is needed to check the valve guide wear as well as the piston rings..- Nick at Pelican Parts  
LoopyComments: 1990 Carrera, dies while driving, no performance or drivability issues, cycle ignition key and it immediatelly starts and runs fine? The ignition switch has been replaced to the tune of many dollars. When this happens all accessory functions shut down also, ie radio programming etc. Comments, thought soulution perhaps, thank you.
September 12, 2012
 Followup from the Pelican Staff: Looking at the circuits, most of them are fed directly from the ignition switch. I would check the connection and condition of the wiring at the back of the electrical portion of the ignition switch. - Nick at Pelican Parts  
ACComments: My 1987 911 had a surprise today. I drove it around all day. WHen I stoped at the evening soccer practice and let it sit for an hour. It would crank fineno battery issue but would not start. Came back to it in 2 hours, it perked up like nothing had happened. I would appreciate any insights.
August 30, 2012
 Followup from the Pelican Staff: If your engine doesn't start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.

if it is intermittent or only happened one time, it will be tougher to get to the bottom of the problem. If you want to take a shot, try replacing the DME main relay. It can cause the issue you described.- Nick at Pelican Parts
 
RosalindComments: Hello I have a 1986 3.2 Carrera which has been standing in my garage for some time. I tried starting it but would only turn over very well but not start. I could here the relay click in when the ignition was turned on, but noticed the fuel gauge showed no fuel, although there was some fuel when laid up. Put a good 2 gallons in and eventually the engine fired up. After approx. 5 minutes running and warming stationary the engine ran nicely but then became lumpy and stopped. Returned 2 hours later and it started and ran well instantly and died after about 30 seconds. tried again, would fire but not start. Tried next day, would start and run fine for approx. 30 seconds and dye again and again would fire and try to start. Sounded like a fuel starvatin problem. I am wondering as the car stood for a while and perhaps the fuel evapurated or 'leaked' would the new fuel I added need bleeding to the injectors? or can you please advise of your advice. Thank you for your time.
July 16, 2012
 Followup from the Pelican Staff: Drain the fuel tank and replace the fuel filter. Fuel does not have a very long shelf life and whatever is in your vehicle is likely bad. Fresh fuel and a new filter may be all you need. There is no reason to bleed the fuel injector, Any air trapped in the lines will come out when cranking. the engine. - Nick at Pelican Parts  
LesComments: I have a '89 C4. Intermittent starting problem. When the key is turned to start I can hear a click but the starter will not engage. After multiple attempts the starter will finall engage and start. I've replaced: starter, DME, ignition wiring to starter, new ignition switch, battery cables, battery. Any suggestions. Thanks.
April 10, 2012
 Followup from the Pelican Staff: This sounds like a bad connection to me. You're going to have to perform a voltage drop test to the starter to see if there is a bad cable. There should be no more than 0.5 volt drop when you attempt to start the engine. - Nick at Pelican Parts  
FredComments: I have an 87 911. Starts fine, will not idle and wants to die when the accelerator is pressed to quickly...it does not want to accelerate. At operating temperature, it runs fine. I have replaced the idle air control valve, the cylinder head temp. sensor, fuel filter, did a complete tune up with valve adjustment. I've checked the mass air flow sensor with a digital ohm meter, and checked the ambient air temp sensor, all check normal. What do I check next?
January 6, 2012
 Followup from the Pelican Staff: This could be a fuel delivery problem of an issue with the mass air flow sensor, or unmetered air leak. I would check fuel pressure, volume and quality. Then check for vacuum leaks and test the mass air flow sensor. - Nick at Pelican Parts  
WilliamComments: I am William Briggs/Briggs Auto LLC
My present struggle is a 2001 911 Coupe that will only start when the interior lights, hood openers,windows and remote key functions.
By no start I mean that there is no crank.
We have replaced the auto's battery as well as the key's battery.
Any previous experience?
Please help,
William
November 30, 2011
 Followup from the Pelican Staff: Your question is not too clear, but I would of course suspect the alarm module, which is located under the driver's seat. Sometimes (particularly on convertibles), these get wet and then short out and start causing all sorts of odd problems like this one. You can also try running the routine "Sports Car Handover" from the Porsche PST-2 or PIWIS tool - that tends to fix a lot of these odd issues. - Wayne at Pelican Parts  
WilliamComments: I am William Briggs/Briggs Auto LLC Porsches since 1976.
I am presently struggling with a 1984 911 that will start every time by push starting in second gear but seldom will it start by cranking until warm.
We have replaced and or switched out: DME relay x3,ECU, ignition switch.
Cranking speed is quite good.When cranking and no start there is no spark.
Please help.
William
November 30, 2011
 Followup from the Pelican Staff: If spark is good, does the vehicle start of you add fuel to the engine? First thing is to find out what it will take to start the engine. If it starts every time you roll it, there could be a voltage drop issue from the main relay or the ignition switch. - Nick at Pelican Parts  
SteveComments: I have a 1981 911 SC... It recently was unable to start although it sounds like the battery is fine as it wants to turn over. I started looking over the engine and the only thing I could find was when I took the air filter cover off and took the air filter out my pop off valve was broken off and lying there. Would a broken pop off valve prevent the engine from starting? Thanks for any advice!
November 12, 2011
 Followup from the Pelican Staff: I think the vehicle would still start and run.

If your engine doesn't start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
BoojayComments: just purchased 85 911 radio ant in glass poor reception can I install booster? your thoughts
October 26, 2011
 Followup from the Pelican Staff: First check that the antenna is in good shape and the connections are good. A booster can hep, but not if the antenna is faulty. - Nick at Pelican Parts  
88CarreraTargaComments: On a 1988 Porsche 911 3.2, if there is spark at the spark plug when cranking, does this validate that the reference sensor and DME is working correctly?
October 18, 2011
 Followup from the Pelican Staff: I would check injector pulse also. This would confirm the sensor is working. - Nick at Pelican Parts  
Big BriComments: i have a 1984 911. it will start on starter fluid. fuel has been drained and replaced since it was old. fuel pump works fine. how do i test the injectors?
October 7, 2011
 Followup from the Pelican Staff: install a fuel pressure gauge on the fuel rail test port. Then cycle the injectors using an injector tester. Measure the amount of fuel pressure that is dropped with each injector. Remember to reset fuel pressure at the beginning of each individual injector test. - Nick at Pelican Parts  
jamesaComments: i am now told that i need an additional sesor replaced on my 911, 1984 Targa. i had the cam sensor replaced earlier now they tell me this sensor is on the transmission. help me on this. How munch can this sensor cost?
August 24, 2011
 Followup from the Pelican Staff: I would have to know the specific sensor being replaced to give you an guestimate. - Nick at Pelican Parts  
PeteComments: I have a 1979 sc that starts and runs perfectly but will not shut down when i turn the key to off. I have to stall the engine in gear.
August 9, 2011
 Followup from the Pelican Staff: Sounds like the ignition feed is shorted and not being switched off when the key is. You can confirm this is the issue by check the wires for voltage at the back of the switch. - Nick at Pelican Parts  
911-targaComments: Hello ,I have a 1980 911 SC and it wont Start at all,it idls ,we checkt relay,Sparks,vacuum leeks,fuel-filter-fuel-pumpworks,no funny noise...somebody got an idea...??!!we are at the end of our wisdom...:-
July 11, 2011
 Followup from the Pelican Staff: If you have spark and fuel, you have to be missing compression. Check engine compression, if it is off, engine timing may be faulty. - Nick at Pelican Parts  
Big DComments: I have a 86 911 Targa. Just installed new rear shocks. A hose going to the air filter housing at the back of the engine became disconnected. I started the engine and left to let it warm up. When I came back in the garage it was idling rough. I tried to give it some gas thinking it would fix it but it would not accelerate. I turned it off and started looking for a disconnected hose or wire and found the only disconnected one was the one going the back of the air filter box. I hooked it back up and now it won't start. It ran perfect before this and started right up. Also now I smell a weird smell when I turn it over.Any ideas? Would love to see how it drives with those new shocks
June 19, 2011
 Followup from the Pelican Staff: If your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.
The main relay is a common issue. - Nick at Pelican Parts
 
SurfComments: '88 Targa. A month ago while driving 95 deg. dayengine shuts down at 4000 rpm. as if no fuel. After 20 min. got it started but at 4000rpm it shut down again. Local mechanic said fuel pump pressure good but filter blocked & replaced it. Month later 95 deg day at 4000rpm it shuts down near Porsche dealer. They said pulse sender 2 needed replacing. 7 hours & $850 later while they were test driving it, at 4000rpm it shut down with the mechanic. Any ideas I can forward to them? Thanks.
June 4, 2011
 Followup from the Pelican Staff: Could be the main relay failing. If your engine doesn't start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
jhComments: I have an 84 911SC. New Battery. Just bought the car and it started and run perfectly. Next time I got in it - won't start. Just clicks and then "buzzes". New battery and all connections seen good. Put on a charger in case and no good. What could it be?
May 8, 2011
 Followup from the Pelican Staff: You could have a bad battery cable or bad starter motor. - Nick at Pelican Parts  
ScottyComments: My son has 2004 911. Car has been garaged 6 months. Battery recharged. Starter wont turn over. Using jump leads from another car the starter appears to want to turn, but head lights left and right flash alternatively instead. There is no large draw when jump leads are attached. Any ideas on what could be causing this. Car was running fine before garaging.
March 4, 2011
 Followup from the Pelican Staff: The battery in your car will drain a little bit every day if you don't put a battery maintainer on it. After sitting drained / empty for several months, the battery is probably completely dead and will probably not come back to life again. I would replace the battery, particularly if it's the original one in the car. I have an article on this right here, as well as the steps required to install a battery maintainer: http://www.pelicanparts.com/techarticles/Boxster_Tech/81-ELEC-Battery/81-ELEC-Battery.htm - Wayne at Pelican Parts  
FatboyComments: I have a "No Start" Problem 0n my 84' 911 Targa. No power to the fuel pump fuse. I jumped the fuse and can here the fuel pump humming but still "No Start" any ideas where to go from here?
December 31, 2010
 Followup from the Pelican Staff: The pump shouldn't run until the car is trying to turn over, so not having power to the pump when the key is in the ignition is typical. It sounds like your problem lies elsewhere. I'm going to copy your question to the technical forums, and perhaps the users there can offer additional assistance. - Wayne at Pelican Parts  
ABComments: I have 2000 911 carrera, got air in cooling system, I relace that air by using the air valve and temp. come's to normal and water level become normal as well, but temp. red lamp still giving a worning !!!
my quastion is how to reset this worning lamp?
thx
November 22, 2010
 Followup from the Pelican Staff: If the lamp is blinking it means that the tank is low. Or, the sensor is not working properly. You also need to properly bleed the cooling system, see this article here: http://www.pelicanparts.com/techarticles/Boxster_Tech/29-WATER-Flush/29-WATER-Flush.htm - Wayne at Pelican Parts 
QuintonComments: I can't thank you enough for posting this article..probably savedme at least $500! I jumped the circuit like you mentioned in the article and heard the sweet hummmm of the fuel pump! car turned right over after sitting for past 6 months. Thas for eliminating stress in my life! I wasn't looking forward to the towing bill on top of the maintenance to fix the problem!
September 6, 2010
 Followup from the Pelican Staff: Cool, but now you need to find out why the pump wasn't being turned on automatically by the DME? - Wayne at Pelican Parts 
BobComments: Where is the fuel pump located on a 1984 3.2 911 ?
August 1, 2010
 Followup from the Pelican Staff: Should be in the front trunk, on the left side of the car (if you're sitting in it), right below the fuel tank. The hose that connects the fuel pump and the bottom of the tank is 90mm in length. - Wayne at Pelican Parts 
ChrisBennetComments: Regarding #9: "swap in a known working DME computer from a 911 friend"

Instead, I would recommend trying your "bad" DME in your friend's "good" car. Reason: A car can damage the DME. Example: Sometimes the idle stabilizer short out and damage the driver transistors in the DME. If you try your friend's DME in your car now, you may damage *his* DME as well.
May 23, 2010
 Followup from the Pelican Staff: Thanks for the input on this one. I have to agree, you will save your friend's control module is there is a short in your vehicle. - Nick at Pelican Parts  
84Targa 3.2Comments: Wow. I have an '84 Carrera 3.2 and today it just woulnd't start. I tried hot wiring the fuel pump fuse per your instructions #3 and it started up like a champ. Continued to run after taking the hot wire off and it seems to be starting OK now. Guess I better make a trip to pick up a DME relay as it sounds like it is required shortly.

Thanks so much for this troubleshooting page, pelican. I saved me quite a bit of frustration. You guys carry the DME relays?
April 29, 2010
 Followup from the Pelican Staff: We certainly do, they are located in our catalog right here: http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=911M§ion=FULmot&page=2&bookmark=9&part_number=911-618-154-00-M252 - Wayne at Pelican Parts 
druComments: i have a 1987 3.2 carrera cab, it starts ok from cold but sometimes when warmed up it takes a few attepts to start it and sometimes,doesn't turn over at all, whats the most likely cause, its been recentley service and has a new dme. any help would be greatly appreciated.
March 29, 2010
 Followup from the Pelican Staff: This could be a bad main relay or fuel pump. If your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
RobertComments: I have an 84 911. I put a jumper wire as you suggested at the fuse box. The pump began running so I started the car. It ran just fine. Next, I turned off the car removed the jumper wire and restarted the car. It restarted everytime just fine. It slso idle's just fine. My question is, does this still mean it's the dme relay causing my problem? Since the car starts without the jumper now, I'm a little perplexed. One other thing the car has been doing for some time, and I wonder if it could be related is this. The dash lights, head lights, glove box lights all flicker eratically all the time. Is this related? Thanks for any help.
January 25, 2010
 Followup from the Pelican Staff: It could be the relay. It may be working now and failing intermittently. - Nick at Pelican Parts  
Roc DocComments: I have an 85 3.2 in my 76 Targa, and the DME that it came with appears to be from a later car. It also has an Autoauthority chip in it. I decided to try another brand chip, and now it doesn't start easily when it's warmed up. It starts fine when it's stone cold, but will sometimes take 30 seconds of cranking for it to fire once it's up to operating temp. I fattened up the idle mix two full turns but the symptoms are the same.
January 3, 2010
 Followup from the Pelican Staff: if the problem wasn't there with the older chip, I would go back to it. hard to say why one chip worked and the other didn't. - Nick at Pelican Parts  
jayComments: I have an 88 carrera coupe and the problem is that the idle is erratic it goes up and down up and down. The car was parked for a couple of years. I did the tune up and dropped the tank and drianed it put new fuel in it. Any suggestions?
December 17, 2009
 Followup from the Pelican Staff: Idle "hunting" is caused by the mixture being off. You can take that to a mechanic and have him check the mixture and adjust it using the screw on the air meter. It also may be caused by vacuum leaks - I would check all of your hoses and boots carefully. - Wayne at Pelican Parts 
TomyComments: Gents, I hope somebody can suggest a remedy. I have a 911SC 1982 in good conditions. I had no problems for a long time but recently on a very hot day in heavy traffic the engine stoped. After about half a hour the car restarted but run only a kilometer before it stoped again, I had to be towed home. Is there a temperature sensor in the engine to stops the engine from overheating? The temperature gauge was showing high but was not in the red. Car apears to be OK now but I lost confidence to drive any distance. Thanks, Tomy
December 13, 2009
 Followup from the Pelican Staff: It could be one of a number of things. I would post this question on the forums ( http://forums.pelicanparts.com), and then we can work it out for you there. - Wayne at Pelican Parts 
GlennemannComments: I have a 1979 911SC. The engine cranks but will not start. Any suggestions what can be wrong?
October 31, 2009
 Followup from the Pelican Staff: Could be one of a hundred different things. I would check to see if you have fuel and spark getting to the cylinders... - Wayne at Pelican Parts 
CTVComments: I have a 1982 911 SC, my problem is that when I restart the car after shutting it off for a few minutes only when the engine is still hot the idle or RPM is runnning erratically, up and down, for about 3-5 minutes before it stays still around 900 to 1000 RPM, and some time the engine dies when the RPM is going up and down. I have to keep my foot on the gas pedal for at least 2 minutes to stable the erratic idle. I was told that the cold start valve is not working right one time. On other time, I was told there is a vacuum leak. I have checked all vacuum lines and found no leakage. I was also told that the cold start valve has nothing to do it with it. Please advise me what to look for. Thank you.
October 13, 2009
 Followup from the Pelican Staff: These types of problems can be difficult to diagnose over the Internet. On my 911SC (1982), I had a similar warm-start problem, and it was related to vapor lock in the fuel lines. The fuel pump has a check-valve built into it that is supposed to hold pressure in the lines when the car is off. This valve works in conjunction with the fuel accumulator which acts like a big spring. When either one of these components fail, the fuel is no longer under pressure, and you can have difficulty starting when warm and/or erratic problems right when you start up warm.

On the other hand, you may have some vacuum leaks too, as the warm start problem I described above typically goes away a few seconds after starting up. If you can borrow a smoke machine, I would run it through the car and see if you can discover any vacuum leaks. - Wayne at Pelican Parts
 
dipstickComments: issues the first, the dipstick was dropped into the oil tank, I tried several times, cant seem to reach it. whats the easiest way to remove it.
September 8, 2009
 Followup from the Pelican Staff: Try using a small magnet to fish it out or a small claw style pick up tool. - Nick at Pelican Parts  
KnaveComments: Jose - replacing the temp sensor in cylinder #3 fixed this problem for me.
September 5, 2009
 Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help. - Nick at Pelican Parts  
joseComments: I have a starting problem when my engine goes hot. 911 3.2 86 I change the DME relay.. when its cold starts good, when goes hot the engine goes down...I take out the temp head sensor and the engine starts again with idle hi rpms about 2000 , do you have the ohms of the head temp sensor.. to check its ok?.. do you think this is a problem? I check an change the gas filter too but I have the same problem
August 2, 2009
 Followup from the Pelican Staff: I personally don't like working on the 1984-89 cars because the Motronic system doesn't give out any error codes - you have to guess at what's wrong. It may indeed be the cylinder head temperature sensor. I don't have the resistance readings here, but I'm pretty sure if you search the forums you can find them. - Wayne at Pelican Parts 
cascresComments: I have 2003 911 carrera - trouble starting - have to clutch several times - is there a sensor by clutch that might be damaged??
July 12, 2009
 Followup from the Pelican Staff: Yes, there is a clutch pedal switch that prevents you from starting the car without first pressing in the clutch pedal. - Wayne at Pelican Parts 
LCComments: I have a 1984 911 that ran Monday and won't start today. What does the tach at zero have to do with anything? Isn't it electrical and only registering after running?
July 9, 2009
 Followup from the Pelican Staff: I'm not sure, I don't think the tach has anything to do with the engine problem - the tach is controlled by the DME which may have a problem. Try replacing the DME relay? - Wayne at Pelican Parts 
Targa86Comments: If you have a "will not start" problem and the tach is pegged at zero it is a DME problem, change the DME relay.
June 26, 2009
 Followup from the Pelican Staff: Thanks for the Info. We appreciate it.
- Nick at Pelican Parts
 
MikeComments: I have a 1976 911 s. Any other advice for it?
June 9, 2009
 Followup from the Pelican Staff: Tons! Check out our 911 Forums: http://forums.pelicanparts.com- Wayne at Pelican Parts 

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