Join Date: Jan 2003
Location: Rapid City SD, Black Hills of South Dakota
164 Firewall Fuel Hose Replacement
The following info is available by PDF download at the bottom of this post.
This guide shows how to easily replace the two front fuel hoses that connect the underbody steel fuel lines to the upper engine compartment steel fuel lines. There are two lines, a feed line and a return line. The feed line is pressurized to about 45 psi, while the return line is under no significant pressure.
Failure symptoms of these rubber fuel lines (and any in the engine compartment), are outright leaks onto the ground, but more likely seepage with the smell of raw fuel being drawn into the passenger compartment. Any gasoline leak is serious and must be dealt with right away. With a flashlight, looking down the firewall from above with a good flashlight, you can see these hoses. If the hoses still have the pinch-on Oetiker hose clamps on them, the hoses are probably original and are in desperate need of changing, regardless if they're leaking or not. The hoses are not as hard to replace as you might think at first glance. With a couple of tricks, it's a relatively easy job.
It is my recommendation that when changing these hoses, that you renew all the rubber fuel line in the car, i.e. at the fuel filter, firewall, and engine compartment. Hose is cheap. Engine fires and tows are not. This guide only discusses the firewall lines. The rest are straight-forward, easy replacements.
Here is a schematic of the rubber hoses in the fuel system:
Supplies you will need:
1. About 6' of 7.5mm fuel injection grade rubber hose. This type of hose has a plastic inner wall to better resist the pressure of the fuel supply pump. On the return lines, since the pressure is much less, regular fuel line will do, but for the pressurized side, you MUST use FI grade fuel line. My recommendation is to use FI grade hose on everything. As an expedient, limp home measure, you may be able to use 5/16" FI grade hose, but probably will require double-clamping not to leak. Regardless, 7.5mm is the correct size to fit the metal fuel pipes and that is what you should use.
2. Fuel injection grade hose clamps/
Oetiker crimp-style clamps, NOT normal worm-drive hose clamps. The crimp-style clamps are very good and were OEM from the factory. Normal screw type FI grade clamps are cheap and available at any auto parts store. Size is "11-13mm."
3. Normal hand tools. If you chose to use the crimp-style clamps you will need the crimping tool, such as the Knipex Oetiker 1099 side jaw pliers.
1. Bleed down fuel pressure from the feed side of the fuel lines. You can do this by letting the car sit overnight, or disabling the fuel supply pump (pull the relay) and running the engine until it dies of fuel starvation.
2. Disconnect the fuel feed pipe from the front fuel manifold.
3. Remove the mounting bracket for the rear fuel line (return line) from the false firewall.
4. Disconnect the fuel hose to the fuel return pipe.
5. Jack the front of the car and secure with jack stand(s).
6. Remove the right front wheel and plastic inner fender liners.
7. Remove the lower left timing belt cover to allow wider access to firewall hoses.
8. IMPORTANT: Determine which under body fuel pipe is the feed and which is the return. Mark one with ribbon or tape. When you go to install the new hoses, it'll keep you from hooking them up incorrectly.
9. Loosen/remove only the lower Oetiker clamps from firewall hoses. It's possible that you can just pull the hoses off the lower attachment points by having an assistant pull on the upper metal fuel pipes while you hold the lower pipes. If not, then take a pair of vice-grips and grasp the crimped part of the lower Oetiker clamps and twist them back and forth. It will likely pop-off or loosen to the point that the hoses can be pulled off with the top fuel pipes. If not, add a thin screwdriver to try and assist. You're not reusing the clamps, so don't worry about damaging them. The under body steel fuel pipes are pretty rugged so you can put pressure on them to reach them.
CAUTION: Fuel will likely leak out of the pipes when you disconnect hoses. Have an extinguisher close by, just in case.
Last edited by Roadtrip; 09-21-2015 at 08:32 PM.