97 GMC Sonoma 2.2L Fuel Pressure Relief

I am trying to do what I thought was a simple fuel filter change. However, I am having suprising difficulty determining the fuel pressure relief procedure on a 97 GMC Sonoma with the 2.2L engine. I have two manuals which have conflicting methods on this dangerous work.

The Haynes manual says to loosen the fuel line outlet fitting at the fuel filter with rags catching the spray. This seems OK, but not very desirable or safe.

My Chilton manual has four different procedures for the 2.2L alone! The 1997 has its own method, which says to raise the vehicle, unplug the fuel pump electrical connection, start the engine and let it run until it stalls, and try restarting to make sure fuel has been depleted. This seems far better, except how do you access the fuel pump electrical connector? There is no access to it since it is right on top of the fuel pump, which is on top of the fuel tank. With everything so tightly packaged, I can't see it, let alone unplug it. It seems unreasonable that to change the filter I would have to drop the tank. What should I do?

I don't think I can use another procedure, since the Chilton manual is so specific. Some people say to pull the fuel pump fuse, pull the fuel pump relay, or even bleed the fuel rail service port valve. If I pulled the fuse, I would think it would stop the engine before the residual fuel was depleted, since it also controls the PCM. Pulling the relay possibly might be detected by the PCM. Finally, I don't believe I have a test port on my fuel rail, since the fuel pressure check requires removing the fuel filter and installing a T-fiting with the fuel pressure gauge. Models other than mine do have a Schrader valve.

Any ideas? Thanks for your input.

Reply to
inboxjm
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AFAIK, you should be able to access the fuel pump plug. It should have a pigtail long enough so you can unplug it without lowering the tank/lifting the bed. If not, a good rag or two around the Schrader valve on the fuel rail and press the needle in should be fine. Remember, you're not draining the fuel, your just relieving the pressure, very little fuel actually comes out. More fuel will come out of the filter when you remove it, but at least it won't spray you in the face.

Oh, don't smoke while you are doing it and keep open flames away from your work area.

Steve

Reply to
Steve Mackie

I don't know if you finished reading my post, but do all engine setups have the Schrader valve? I didn't think mine had one, since my manuals don't mention it for my engine.

Reply to
inboxjm

Would the connector also be covered in the protective wire sheathing that runs the length of the frame?

Reply to
inboxjm

Once you get to know me a little better, you'll learn that if I have to scroll, I don't read the whole post. I got the gist of it: you are changing a fuel filter on a GM truck and you're wondering about the fuel pressure relief procedure. Reading the rest would have just depreciated the value of my mouse.

There is some sort of fuel pressure testing port somewhere in the engine compartment on the fuel line, I'm not familiar with the truck 2.2L so I can't tell you exactly where. Take a look, you'll find it. Most likely will have a black plastic cap on it.

Steve

Reply to
Steve Mackie

If its like my 96, the fuel pump relay is behind the glove box. I changed my filter without purging it.

Bob

Reply to
Bob Urz

It's just the fuel that's left in the line. Fuel pump is off. I just disconnected and let the gas drip out. No biggie.

Crank motor when done to prime it. Easy.

b
Reply to
Brent

I did the job just loosening it up and there wasn't any pressure; just a flow. Although, the truck had been sitting for a day or two. Who knows what would have happened if I had done it after waiting only 10 minutes. I have changed fuel filters and worked on lines before, so it's not like I haven't come into contact with gas. I just didn't want to be caught off guard by any pressure, like some people have. I'm going to look for the test port to see if it's there anyway. However, I have my doubts since if it was there, why wouldn't the Chilton manual use it for the 97-98 2.2L models. They do employ a test port on the 94-96 and the 99 2.2L models, as well as the 94-99

4.3L models for fuel pressure relief. It seems odd to me. What could be the difference with the 97 and 98 models that would require two alternatives? Thanks, as always.
Reply to
inboxjm

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