92 Jimmy dying getting worse.

[anthonyalan]

I have a 92 4X4 GMC Jimmy W VIN code and it's not running! It is not my primary driver, but would still love to drive it and keep it runnning(for when I want to sell it!)

When it was running, my dad drove it to save on gas, since he has a lifted truck. It started with it slightly missing when at cruising speed going down the road. As the days progressed, so did the problem.

It started missing more, and harder. When 1/2 accelerating, or at WOT, it did not miss, or when Idling. It got worse and started missing all the time. It finally got so bad that it died on me when I was driving it at a stop sign.

I was able to get it home by romping on it and then letting completely off the accelerator. It eventually got so bad that I could not keep it running. It would start and if i kept it revved it would run, but would die if i let it idle. I changed the fuel filter and air filter. No luck. When I took the fuel filter off, the gas that ran out was extremely dirty, so I just took the gas tank off and dumped out the gas, the gas wasn't near as bad as I hoped it would be(I would then think that a rusted tank making the gas extremely dirty and being the problem).

I let it sit for about a week, started it up just to see what would happen. It started fine, idled fine for about 3 or 4 minutes. I started to rev it slightly, only to about 2 or 3 grand. the second time I did this it started missing again, and I couldn't get it started again after it died. I also noticed that when it died, the oil pressure dropped, and then several seconds later it went all the way up. I have a digi dash so I didn't think much of it, but maybe someone that reads this will...

I believe it's a fuel problem, not electrical, but could be wrong! Any help will be GREATLY appriciated! Also, links to other threads that may be helpful would be appriciated as well. Thanx for all the help in the past and the help for the future!!

[maxwedge]

Get a fuel pressure gage on it see what you have, basic diagnostics are in order here. You went thru the problem of getting that tank out, if you had checked the fp first this might have saved you some work, also how about the tank filter? FP is 55-61 psi.

[anthonyalan]

tank filter? would that have been on the bottom of the sending unit/fuel pump assembly?? I noticed it but didn't know waht to think of it, I didn't look at it very well. Well, we couldn't get it anywhere to check the pressure, and I don't know how to do it myself. How easy is it? Plus, the fuel pump was changed when I got it in the spring of 04, so I didn't think that would be it...

[maxwedge]

You don't know what is wrong here, confirming fuel pressure when this happens is the first step to fixing it, a gage cost about 50.00. If you cannot perform basics, you really should enlist some help with this.

[Chris Stewart]

In addition to what Maxwedge says, a fuel pressure check kit is available at most chain type auto parts stores. Connect the gauge to the pressure test fitting (Schrader Valve) then turn the keyswitch on. The fuel pump should run long enough to get a good reading...a coupla seconds. Get a kit with a bleeder valve and you can sample the fuel going to your injector.