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Depressurize Fuel System

I am currently working on my third Fox Body, an 89 LX 5.0 Convertible. Just as a preventative, I wanted to change my fuel filter and ran into a problem. On my earlier ones (92 and 93), you could depressurize the fuel system by removing the fuse for the fuel pump, and running the car till it quit (a hack, but it worked). This one (still fuel injected) doesn't have a fuse for the fuel pump, so I'm stuck. The Factory service manual talks about a pressure relief point at the front LH side of the engine, but I can't find it. Any ideas or guidance? Also, I've tried to make performance mods during routine maintenance whereever it made sense. Is there anything worthwhile I can do with the fuel filter while I'm at it? I suspect no, but thought I'd throw it out there. When I bought the filter at AutoZone, there was a more expensive model available, but it was special order, and I couldn't understand the benefit. Again, any thoughts?

Reply to
Jim C
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My '86 does not have a fuse either, rather a fusible link. In the trunk should be a fuel pump intertia shutoff switch, which shuts of the fuel pump incase of an accident. not sure where it is in a Fox 'vert but in my hatchback it's on the driver's side near the tail light. Black plug on the interior panel points it out. in your trunk look for a small black cube with a white button on it. Maybe someone else here can point out it's exact location.

with the engine running, unscrew the switch from its mounting point and give it a whack. it will open, the fuel pump will shut down, the engine will stumble and stall and you will have a nearly depressurized fuel system. simply press the button to reset it, replace it on the mounting, and go work on your fuel system. I do this every year when I replace my fuel filter. I just use a name brand filter.

Kept her running for 21 years and 165,000 miles so far with mainly basic maintenance.

Reply to
Mike Lenker

I've worked on a number of modern (relatively speaking, I own a 66 Mustang so anything with fuel injection is modern) cars, and all have had a fuel pressure test port of some sort in teh fuel rail. It uses the same type of push valve you'd normally see in the wheels. Also AC systems use similar valves.

I wrap the test port with a rag and push the valve in, as if letting air out of a tire. Pressure relieved.

This doesn't exist on 80's mustangs?

Jan

Mike Lenker wrote:

Reply to
Jan

Thanks for the tips. I'm a little nervous about 'whacking' the inertia switch. Given my luck, I'm afraid I'd break it. This pressure test port may be present, I've just never looked for it. Does anyone else out there have more detail on where this would be found? Is there one on each side, or does the one valve depressurize the whole system?

Reply to
Jim C

Just did this on my kid's 87 GT when I replaced a leaking lower manifold gasket. There's a a valve (looks like the one on the tires) on one of the stainless fuel lines on the front right side of the engine. Like Jan said just wrap a rag around the valve and let the air out. After it sits awhile, there's not much to let out, at least on mine there wasn't.

-Scott

Reply to
Scott

there is also a valve in the trunk under the lining on the rear driver side like a button.

Reply to
Mas Plak

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