Replacing 914 Gas Lines in the Center Tunnel

Difficulty Level 5

Difficulty scale:
Adding air to your tires is level one
Rebuilding a 911 Motor is level ten

Figure 1: Fuel lines entering grommet in front end of tunnel

Figure 2: Fuel lines exiting out of the rear firewall

Figure 3: Fuel lines in front of car underneath gas tank

Figure 4: Right-angle fittings exiting firewall

Figure 5: Fuel lines bent underneath the fuel pump

Figure  6: Fuel lines in engine compartment

   The first step in beginning the replacement is to gather all the parts you'll need to complete the project.  To replace the lines that run within the center of the car, I used Edelsman brake lines with English flared fittings on each end. These are the same types of fittings that are used on the 914 brake lines, although those fittings have a metric thread. Where the lines exit the rear firewall, I used right angle fittings to make the bend around the corner to the fuel pump a little easier. Here's a list of what you'll need:

• 3/8" brake lines 60" in length with flared fittings
• 5/16" brake lines 60" in length with flared fittings
• 3/8" brake lines 40" in length with flared fittings
• 5/16" brake lines 40" in length with flared fittings
• 5/16" right angle elbow flared to NPT
• 3/8" right angle elbow flared to NPT
• Female NPT to flared adapter
• Female NPT to flared adapter
• 1/4" and 5/16" Rubber Fuel hose (about 5-6 feet total)
• A roll of Teflon tape and eight small hose clamps
• A small pipe bender

   Pelican Parts can provide you with all the parts that you need in a single kit for assembly. Drop us a line if you're interested, or visit our ordering page for more information on ordering your parts from us.

  The first step in replacing the fuel lines is to remove the fuel tank. I would recommend the removal of the front hood, which is usually a two-person job. I wouldn't recommend attempting it yourself, or you might drop the hood when you least expect it. Following the removal of the hood, you need to empty the gas tank. This can be accomplished a variety of ways. You can remove the belly pan from underneath the rack and pinion, reach up through an access hole underneath the tank, and clamp the rubber lines leading from the bottom of the tank. Then the lines may be clipped, and the tank lifted up on its side where it can be drained at a later time. This method sometimes works well, and sometimes spills gasoline all over the place. Another method is to hook a line up to the fuel pump. A long 1/4" clear hose from Home Depot should do the trick. Clamp the lines leading to the pump, and then disconnect the supply line to the fuel injection. Connect the long hose to the fuel pump, and place the other end in the gas tank of another car. Turning on the ignition will then let the fuel pump empty the tank. Note: this will not work with a car equipped with the 1.8 injection system.  In order to get the fuel pump to run with a 1.8, you need to directly wire the pump to a 12V source. Make sure you don't run the pump backwards by mistake. After the tank is empty, clip the lines that lead from the bottom of the tank. You can throw these away, as it is best to use new fuel lines. Remove the top overfill canister and disconnect the fuel sender line. This step is often overlooked. Loosen the strap that holds the tank in place and lift it out of the car.

Here's some more tips on emptying the tank from Andy Green:
     To get the 1.8 fuel pump to run (so that you can empty the tank, simply remove the air filter top, carefully stick your finger in to the air meter and gently lift the flapper (with the ignition on). This is easier than hot wiring the pump, and probably a lot safer for the electo-mechanically challenged.  You can put the drain hose on the output side of the pressure regulator then flip it out of the engine compartment, over the left side of the car, into your container. This works well since you are standing on the left side to actuate the pump--it is easy to cordinate the flow and the hose, as well as not overflow the container. It can all be done from on top of the car and you don't have to mess with the pressure side of the lines. Also, on either 2.0, 1.7 or 1.8 be careful not to over run the pump when the tank empties. The fuel cools it--no point shortening its expensive little life!

   At this point, it probably would be a wise idea to carefully inspect and clean the tank.  There is almost always a whole bunch of crud in the bottom of the tank. Finding someone with very small hands to reach down into the tank helps a lot. Also, inspect the tank on the outside for areas of rust. I've heard reports of holes forming in tanks where they rest against the felt pads in the inside of the front trunk.

    Once the tank is out, you can remove the old lines. Disconnect the plastic lines from the rubber ones that lead to the fuel pump. Again, throw away these lines and replace them with new ones. The cost of new fuel hose at about a dollar a foot is a worthy investment. Once the lines are free, pull them out of the plastic clips attached to the firewall. At this point, move to the front of the car underneath the dash and gain access to the center tunnel through the access hole near the gas pedal. This will require the removal of the front carpet and/or the center console if you have it installed. This port can be seen in Figure 1. Pull the two lines out of the grommet that fits in the wall. The plastic lines have steel ends on them where they go through the firewall. Proceed back to the rear of the car, where you should be able to pull the lines through to the engine compartment. You  may have to twist and yank on them in order to get them out. You can poke and prod them to through the access holes along the center tunnel.

   Once the lines are out of the car, you can install the new ones. Prepare the lines by cutting off one end of the line and removing the nut fitting.  It is not necessary to deburr the line just yet, as you will need to make another cut when you size the line.  Cover the ends of the lines with tape so that you don't get debris inside them. Insert the two lines into the grommet at the firewall and feed them through the center tunnel.  This may require some prodding through the various access holes in the center tunnel.  I've heard reports of this being a difficult process, but mine went in real easy. It certainly is easier with the engine removed from the car.

   Now you need to size and cut the lines.  Remove the grommet from the front of the car underneath the gas tank.  Bend the lines to feed into the hole where the grommet used to be.  Push the lines into the gas tank compartment as far as they can go.  Now measure the length at which the lines hang out in the back of the engine compartment.  I made my lines sit as close to the firewall as possible as to not interfere with the motor.  This is shown in Figure 2. Measure how much you need to cut off, and then remove the lines from the car. Make sure to add a little bit extra (1-2 in) because you will have to bend the lines to make them fit right into the forward grommet, as shown in Figure 1.  When cutting the lines, make the smaller return line a little bit longer, as the two right angle fittings at the firewall will interfere slightly if they are the same length.  At this time, it would be wise to deburr the edges of the lines with a small file or Dremmel tool.  

    Now, replace the lines in the tunnel and replace the grommet that you removed in the gas tank compartment.  Now comes the tough part.  You need to bend the ends of the lines in order to get them to feed into the grommet.  This takes quite a bit of patience, and is the most difficult part of this task.  I have no real advice on this one except not to over bend the lines; they will not go through the grommet if they are at a significant angle. The lines should stick out of the grommet about 1-2 inches, as shown in Figure 3.

   Once the lines are in the tunnel and through the grommet, then you can replace the gas tank.  I suggest using 1/4" and 5/16" diameter fuel hose to connect to the tank. I also suggest using a length of about three feet, so that you have plenty of working room in case you need to remove the tank again (to install the front sway bar, perhaps?). Clamp every line, even if there wasn't one there to begin with. Make sure when replacing the gas tank that the line doesn't get caught and pinched between the tank and the wall.  Make sure that all your lines and hoses are out in the open before you replace your tank; I recently had to remove and replace the tank three times in about an hour when I realized that there were wires or hoses left underneath.  

   Now, you can attach the right angle fittings to the lines that are extending from the firewall as shown in Figure 4. I originally used brake line fittings as shown in the photos. However, after getting the car back together, I had problems with them leaking. Instead of using the right angle fittings, I decided to use some braided flexible hose instead. This solved all of the leaking problems, because I think that I damaged the pipe fittings during their installation. After you put the fittings on, then you need to bend and cut the 40" lines to lead to the fuel pump.  This can take a couple of iterations as the proper bend and length is not intuitively obvious. These bends are shown in Figure 5.  It may make sense to buy extra brake lines (at $3 each it's worth not having to make an extra trip) so that you have at least another chance if you bend the lines the wrong way.  The entire setup in the engine compartment is shown in Figure 6. The black metal mount attached to the bulkhead is my 914-6 motor mount. When you reinstall the fuel tank, be careful to check to make sure that there is no leakage around any of the connections. Remember that there will be more fuel pressure in the lines when the tank is full, then when it is almost empty.

   There you have it - you shouldn't worry about your fuel lines leaking again, and you've increased the safety of your car.  If you have any questions about this job, drop us line...

JP Noonan has the following to add:

     Well I went to put in new fuel lines in my center tunnel. My car is a 75 so the pump was originally up front. The problem is that on 70-74 the feed nipple from the tank is 9mm and the return nipple is 7mm, this must be what the tech article was based on. However the 75-76 have both nipples as 7mm. Sooo I bought 5/16" line and 3/8" line to replace what was two 7mm (5/16") lines. The 3/8" line fit but just barly. now I have it in there I have to step down to 5/16" line. So to amend the article I would sugest that if you want to replace lines in a 75-76 BOTH lines should be 5/16". Also I would recomend using wire lube or dishwashing soap to aid in pushing the lines through the gromets. Also a problem that may arise (I won’t know until I drive the car) is that the lines may rattle together. One way to help this would be to cover the lines in shrink tubing as they are fed through the fire wall.