Hi there! I have fallen into the spiral of buying parts based on opinion after opinion of everyone I know. Don't laugh, I am new at this do it yourself bit, so laugh quietly please. Hope someone can help, here we go. Have a 1990 chevy 1/2 ton 2 wheel drive 5.7 L TBI. It sat for about a month without being driven, I took it 6 miles up the road, shut it off and went in the store. It started right up when I got back in it, but 2 blocks up the street, it began to idle up a little and then when I stopped at the red light, it missed, sputtered and quit. I got it going with a little cranking and holding the gas pedal to the floor. I made it home, but it missed all the way and the idle stayed up just a little. It would start when cold and run for about 10 minutes, then a huge sucking sound could be heard in the engine and it will begin to sputter and then die, and will not restart til it's cooled off. Since the initial problem where I drove it to town, the parts I have put on it, (new parts from NAPA) include;
TBI gasket
spark plugs
pick up coil
fuel filter
fuel pressure diaphragm kit
throttle position sensor
oxygen sensor
***took coil and ignition module off to be tested, tested good/no problems***
When it starts, runs for 10 minutes and starts sucking/sputtering/getting ready to quit, you can see fuel POURING into the throttle body below both injectors, and the black smoke pours from the exhaust. Any ideas/suggestions would be appreciated. The guy at NAPA told me yesterday it sounded like the bottom o rings were bad on the fuel injectors. Can they alone be replaced or do you have to replace the entire injector? Also, can the fuel filter on the end of the injectors be replaced by themselves, or a whole new injector? I have an LMC truck catalog but did not see the injector filters or o rings in it for sale seperately? HELP!!!

 

I assume you have no scanner to check it?...

A sensor is most likely "lieing" to the pcm and the pcm is cranking up the fuel.

2 most likely parts would be a bad map or ect sensor....But without seeing readings on a scanner...well,you know how expensive it can get.

good luck bro!

 

yeah i heard of this b4, some sensor starts acting up and it gives the engine gas for a -40 degree start thats probably your problem

 

Sorry to all those who may be upset at the resurrection of dead threads. I do have a reason. I am not going to hold my breath, but the original poster never mentioned if the problem was resolved?

I just bought a 1989 Chevy half ton with a 350 (5.7) in it. It seems to be running extremely rich. When I first looked at the truck to consider buying it, it would not start unless you hold the pedal to the floor, and it would not stay running. I did a compression test, and the range was from 150-175PSI between the cylinders. The spark plugs were BLACK when I pulled them. The service engine light soon light was on at this point. Put in a new set of plugs, and it started right up. The service engine soon light was off now. After a few minutes it started to act up. After about 10 minutes, the truck was back to where I first saw it, it would not start unless you hold the pedal to the floor, and it would not stay running. Pulled the #1 cylinder plug and it is black. The service engine soon light ha NOT come back on. At this point, I was leaning against buying the truck and a potential headache, but the seller immediately dropped the price to $300 so I felt obligated to take on the challenge.

I bought a code reader but have not had an opportunity to do anything further as that annoying thing called work has got in the way. I am at work now and had some time to sign onto this forum to ask questions.

ANY insight would be appreciated.