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Pelican Technical Article:

Fuel Pump Testing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$300

Talent:

*****

Tools:

10mm socket, DVOM, test light, jumper wires

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

Fuel pump, fuel pump relay

Hot Tip:

Check fuel level before digging too deep

Performance Gain:

Properly functioning fuel pump

Complementary Modification:

Replace fuel filter

In modern Volvo automobiles the fuel pump is electric and located inside the fuel tank. The fuel pump creates positive pressure in the fuel lines, pushing gasoline to the fuel rail, where the engine control module (ECM) controls flow to the engine via a programmed fuel injection map. In tank fuel pumps have many benefits. The fuel is submerged in fuel keeping it cool, preventing vapor lock and electrical issues. The fuel pump delivers a constant flow of gasoline to the fuel pressure regulator, located in the left side of the fuel tank. The fuel then flows to the fuel rail at a regulated pressure and volume.

A faulty fuel pump can cause poor engine performance and hard starting problems. When they fail completely you may be left with an engine that doesn't start. If you suspect your fuel pump has failed, you can confirm the fuel pump received the correct voltage when commanded ON by the fuel pump relay using a digital volt ohmmeter (DVOM). If the correct voltage is present, but the pump does not activate, it is likely faulty. Use the DVOM in conjunction with a wiring diagram to determine the correct terminals for testing. You can access terminals under the cargo compartment carpet, below the access panel.

The fuel pump is located in the right side (passenger side) of the fuel tank. There is an access panel below the cargo compartment carpet.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Pressure testing: Locate the fuel pressure test port at the right side of the fuel rail (red arrow).
Figure 1

Pressure testing: Locate the fuel pressure test port at the right side of the fuel rail (red arrow). Remove the fuel test port cap (inset).

Pressure testing: Install the correct adapter for your gauge to the fuel rail (red arrow).
Figure 2

Pressure testing: Install the correct adapter for your gauge to the fuel rail (red arrow).

Pressure testing: Connect a fuel pressure test gauge to the test port (red arrow).
Figure 3

Pressure testing: Connect a fuel pressure test gauge to the test port (red arrow). Next, start or attempt to start the engine. Fuel pressure should be 40: 44 PSI with the engine running or when cranking. Once you test the pressure, recharge the fuel system by cycling the key or running the fuel pump. Note the fuel pressure. Then allow the fuel system to sit under pressure for 30 minutes. It should hold a 28: 40 PSI.

Electrical testing: Working in the cargo compartment, remove the storage compartment lid by opening it and lifting it (green arrow) out of the mount (red arrow).
Figure 4

Electrical testing: Working in the cargo compartment, remove the storage compartment lid by opening it and lifting it (green arrow) out of the mount (red arrow).

Electrical testing: Slide the carpet panel out of the storage compartment (red arrow).
Figure 5

Electrical testing: Slide the carpet panel out of the storage compartment (red arrow).

Electrical testing: Pull the side trim panel (red arrow) up to remove it.
Figure 6

Electrical testing: Pull the side trim panel (red arrow) up to remove it. The right side is shown. Repeat this step for the left side.

Electrical testing: Remove the two 10mm storage lid fasteners (red arrows).
Figure 7

Electrical testing: Remove the two 10mm storage lid fasteners (red arrows). The right side is shown. Repeat this step for the left side.

Electrical testing: Remove the storage lid from the vehicle (red arrow) to expose the wiring harness junction (green arrow).
Figure 8

Electrical testing: Remove the storage lid from the vehicle (red arrow) to expose the wiring harness junction (green arrow).

Electrical testing: Working at the fuel pump access panel, remove the five 10mm fasteners (red arrows).
Figure 9

Electrical testing: Working at the fuel pump access panel, remove the five 10mm fasteners (red arrows). Then remove the access panel from the vehicle (inset).

Electrical testing: Locate the fuel pump electrical connector (red arrow).
Figure 10

Electrical testing: Locate the fuel pump electrical connector (red arrow). Pull it apart to disconnect it (inset).

Electrical testing: Connect a DVOM across the fuel pump terminals.
Figure 11

Electrical testing: Connect a DVOM across the fuel pump terminals. These are the two terminals on my subject vehicle. The red arrow points to the battery positive feed to the pump. The yellow arrow points to the battery negative feed to the pump. You will be testing voltage across the large wires at the connector. Turn the key ON. The DVOM should read battery volts (around 12 volts). If no voltage is found, check the relay and fuel pump fuse and relay. With the key ON, the fuel pump will receive voltage for a three to five seconds to prime the system (if engine doesn't start).

Electrical testing: I suggest load testing using a test light and a DVOM.
Figure 12

Electrical testing: I suggest load testing using a test light and a DVOM. Connect the DVOM across the fuel pump electrical connector terminals and take a reading. It should read battery volts when the key is turned ON. Then connect an incandescent bulb style test light to the battery ground and touch the test light probe tip to the positive wire you are backprobing with the DVOM. Your reading should hold steady. A maximum drop in voltage of 0.5 volts is OK. Anything more is a problem. In this photo, voltage held steady. If you have no voltage to the pump, see the following steps for checking the relay function.

Electrical testing: Remove the under hood fuse panel cover.
Figure 13

Electrical testing: Remove the under hood fuse panel cover. Check the fuel pump fuse. On my vehicle (V70 base 1999) it was fuse 3 15 amp (red arrow).

Electrical testing: Working in the left side of the wiper cowl, loosen the four T20 Torx screws (red arrows).
Figure 14

Electrical testing: Working in the left side of the wiper cowl, loosen the four T20 Torx screws (red arrows). Then remove the electrical compartment lid (inset).

Electrical testing: The fuel pump relay is red and is in position 103 and labeled 103 (red arrow).
Figure 15

Electrical testing: The fuel pump relay is red and is in position 103 and labeled 103 (red arrow). Remove it by pulling it straight out. You now have access to the fuel pump relay terminals. First check that the relay has power with the key in the run position. You can also jump out your fuel pump relay (to bypass it) for testing. The vehicle used in this tech article was a 1999 V70 base. The fuel pump relay position may vary depending on year and model. Double check your fuel pump relay location with the latest Volvo repair information.

Electrical testing: You can check the relay circuit using a digital multi-meter (DVOM).
Figure 16

Electrical testing: You can check the relay circuit using a digital multi-meter (DVOM). Connect the black lead of your DVOM to battery negative, and use the other to backprobe the terminals. Use the following list to cross reference your voltage readings. Keep in mind wire colors and positions may vary depending on year and engine. What you see below is from my 1999 base V70. Other readings should be similar.
Red arrow: Terminal 15: ignition battery positive (purple arrow)
Blue arrow: Terminal 31: battery negative (-)
Blue arrow: Terminal 31b: DME relay control, close to zero volts when DME turns relay on. Close to battery volts when not activated.
Green arrow: Terminal 87 - Feed to fuel pump, battery positive when relay is activated

Electrical testing: Remove the fuel pump replay.
Figure 17

Electrical testing: Remove the fuel pump replay. Connect a fused jumper wire (red arrow) between terminals 15 and 87. See the previous image for terminal locations. This will activate your fuel pump. Check for voltage at the fuel pump as you did earlier. Battery volts should be present.


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Comments and Suggestions:
mikecoutu Comments: I have a purple wire coming off my fuel rail wire harness that came unplugged while replacing my radiator and i cant find where it plugs back into
December 3, 2016
Glenn Comments: Bit late with my reply, but ran your tests, confirmed low voltage, picked up new relay, and away it went.
Thanks very much
Glenn
May 31, 2016
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Glenn Comments: Hi Pelican,
Vehicle 1998 V70XC RH Drive Aust.
I'm about to make the series of checks describe on this page due to the following symptom:

Fuel pump is audible at switch on primesand engine starts. If engine is going to fade and or cut it is likely to do so within the next few minute or 10km of driving. If it doesn't fade lose power as if fuel filter is blocked or pump failing - replaced with new Bosch OE Filter as first fix to no effect then it will happily drive with full power for many hundreds of kms and or several hours without falter.

Once stopped for a few minutes, however, upon restarting the journey it will falter within the initial period described earlier - often this is just a series of fade outs before again being able to drive seemingly forever. On other occasions it will stop and refuse to start, but once started and up and running for a few minutes it will again run forever.

Point of note: when it stops and refuses to to start, fuel pump does not prime no audible priming noise at key activation. Wait a while sometimes seconds, sometimes minutes pump primes on key activation and engine starts. I may have to go through this many times with numerous engine fade outs but not stop until the car runs clean - then I'm off for as many hundred kms as I have fuel in the car.
Questions:

Do you have the voltages for the 1998 XC version? Or are the same as you have listed here?

Can the car be driven for a short period using the fused jumper described? If I can't find fault using your fault finding methods I may need to put it into normal driving condition for about 10 - 15 minutes to 'force' the fault.

What size wire and fuse do you use for your jumper? my fuse in the fuse box is 20, as against yours that shows 15, 20 is also what is shown on the fuse box lid description

Thanks for this great write up by the way very very good and clear.

By the way - I've also attempted the 103 fuel pump controller fix described on another Volvo forum site Matthews Volvo but it made no difference though this does not exclude the unit from the possible fault list
Regards
Glenn
April 25, 2016
  Followup from the Pelican Staff: Use a 15 amp fuse, it will be fine. Voltage numbers should be similar to your vehicle.

It does sound like an issue witht he pump. - Nick at Pelican Parts
 
Keith Comments: I got it fixed. It was the fuel pump. Thank you!
April 1, 2016
  Followup from the Pelican Staff: Thanks for the follow up. - Nick at Pelican Parts  
Keith Comments: I don't get any voltage when doing this. Any thoughts?
March 29, 2016
  Followup from the Pelican Staff: What is the vehicle and year? Voltage on what wire? What are all of your voltage test results? - Nick at Pelican Parts  

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