Hey guys. I think my fuel pump might be clogged or bad. Originally thought that I might have gotten water into my gas as the truck was experiancing trouble staying started and low idle. I went to get into the truck to go to work one night and the truck struggled slightly on start up and it caught my attention so I shut it off and started it again. On the second start the truck almost didn't get started and then it only idled at maybe 100 rpm for maybe 5 to 10 seconds before it died. I didn't get to mess with it by my father and wife checked the battery, cables, and alternator and they all work fined. But on a hunch my father put some STP fuel injector cleaner and fuel system cleaner in the tank when he arrived to look at the truck. About an hour into it they were checking the to see if the fuel pump was activating when the truck was turned on, which it was, when they attempted to start the truck. Truck fired right up no problems. wife drove it around the block, bout 1.5, and put her foot in it as told to. Water was streaming out of the tail pipe and the truck had zero issues. Father wrote it off to water in the gas. I drove it to work the next night, then to the hospital to sit on an inmate, and back home with no issues.
However a few nights later I drove the truck out to a store and when I tried to start it up to return home the truck won't stay started more than 5 seconds and idled no higher than 100 to 200 rpm. Putting more STP into the tank hasn't fixed it and now the truck won't start at all. I'm not looking forward to replacing the fuel pump cause the blasted thing is in the tank, and its got about 15 gallons of gas in it atm. Anyone else think its the fuel pump. Some buddies at work have floated IAC and EGR as well as likely canidates. The truck is a 1996 1500 4x4 5.9 v8.

 

I would check fuel pressure and clean the IAC and throttle body. Any problems under load or while accelerating? Might want to remove o2 sensor and see if it idles any better.

 

......There is a freee download manual in the FAQ/DIY section. It will detail how to clean the IAC. Do not turn the pintle...it will damage it.

Ramzy mentioned removeing upstream O2 sensor. If it runs better, that is indicative of a blown plenum gasket. Remove air intake from TB and look inside intake manifold witha flashilgt. You are looking for oil pooling at the bottom. If this is the case, it may be/may have plugged the cat, which is what removing O2 sensor would confirm. This is when you will want to read the "Be all, end all plenum thread" stickiued at the top of the main forum page.

Welcome to DF!

 

Look for the oil in the intake when you take off the throttle body to clean the IAC valve (and the TB itself). I couldn't see oil in there with the TB on, but once off, sure enough there was oil way at the back.

 

Thanks I'll check all those before we drop the tank. Hope I don't have to do that but if i do i do. Should really drop the tank anyway, the truck is all original as it is, and I have a brand new fuel pump sitting here at the house.

 

Did you check fuel pressure with a gauge?

 

Appeared to be the pump. Switched it out and fired right up. Still gonna pull and clean the IAC.

 

OK its been a couple of days and the truck is still running strong so I guess it was the fuel pump after all.