BL9546

Hi, i have a 92 chevy 1500 1/2 ton that started having some problems. The first thing i noticed was when i stopped at a stop sign and went to take off it choked and almost died. I thought it was from low fuel so i stopped and put premium gas in. Got back in and it wouldnt start for about 4 five second cranks. It is running rough and when put it reverse with a load on it or accelerated quick off start it chokes and tries to die. It is fllooding and dumping fuel after it is killed. Replaced Fuel pump, fuel filter,
o2 sensor, and fuel regulator, still having problem. Cleaned the plugs fired it up it ran fine about 10 minutes no choking, killed it, tried cranking and it was choking again with black smoke. After sitting for a while it will run good until it warms up. Any help will be appreciated,

Raylo

Fuel injection or carb? Did you check/replace the air filter?

BL9546

It is fuel injection, and the air filter is good.

dai

air flow sensors faulty or map sensor

BL9546

the iac seems to be working, but not sure on the map

Raylo

It sounds like that as soon as the engine goes closed loop for some reason the computer is dumping in too much fuel. Maybe a MAP or MAF sensor or some other stuff. The quickest way to check it is to get some scanning software and jack into the cars ALDL connector. Diacom or TTS Datamaster are 2 good ones that will show you the output of the sensors as well as fuel injector pulsewidth. I find it invaluable to have this capability to diagnose the occassional problem with my 2 OBD-I GM vehicles. Alls you need is a laptop, some software, and a special cable. I think some of the handhelds like AutoXray also do this.

cardoc

Coolant temp sensor is also a very common problem.As suggested by Raylo now is the time for a scan tool,even a cheap one to see whats what.Depending on the engine leaking fuel injector poppets also a very common problem.Engine size would help research
Cardoc

mack1

Hi BL9546

Do you smell fuel, or is it leaking out somewhere?
Are you getting any fuel in the oil? Pull the dip stick and smell of it. If the fuel pressure regulator is under the intake manafold, it would sound like a ruptured diaphram, but you said you replaced it. Could be an injector stuck open, but I can't relate that to only occuring when the engine is hot. That scanner that would show pulse length to the injectors would really help. You might be able to probe the injector wires with a volt meter on AC and see if there is a difference between cold and hot engine at idle. A scope would show the pulse lengths, but most folks don't have a scope.

Hope some of these responses will help.
Mack1

BL9546

Ok, i finally had some codes come on the check engine light and it had the Map sensor and ignition control module. My temp sensor is new replaced it not to long ago. I put the map sensor on last night, cleared the codes and drove it for a while and cant get it to mess up or throw any more check engine lights. Before the map sensor was on the check engine light was coming on and off pretty frequent. I am going to drive it some more today to see if it does it again, i will update later today

Also it is a v8 5.7 350 engine

BL9546

And yes the fuel pressure regulator i replaced 2 days ago and there is no gas in the oil.

mack1

Hats off to dai
Figured out the problem and said so in seven words.

Mack1

BL9546

Ok, after replacing the map sensor it has not messed up or thrown any codes, i went ahead and replaced the ignition control module also since that code came up. I reset timing and put new plugs and have not had any problems. Thanks alot for everyones help!!