350 engine

[caterpillar]

I have a 1986 gmc with a 350 and i have a problem with it running, when it is cold and choke is on it runs great, when it gets up to operating temp it is very hard to keep it running, it will run rough or die, if it dies it will start right back up but you have to keep giving it gas to keep it running,,,,,,,, it will not run at low idle, when this happens you can smell gas, it has an edelbrock carb, i was told that they do not need very much fuel pressure,,,,,,, could it be over fueling when the choke is off causing it not to stay running.

 

[djjsr]

First step would be to check for a vacuum leak.

 

[Stinger]

The choke richens the mixture so if it runs poor with the choke on, that means it's running lean without the choke. If it's lean without any carb adjustments then I'd suspect some "gunk" in the carb that is blocking or partially blocking the idle circuit.

 

[Mustangmike]

Dont forget to check the timming chain and gears..Nylon on the cam gear teeth will deteriorate and fall apart. The engine runs when cold as it is on high/fast idle. Just my 0.02

 

[cwroth]

Would check for vacumn leak as well first.

 

[Gary S]

A friend put an Edelbrock carb on his truck similar to yours. After a few months he had similar problems. He tore the carb apart and found small particles of some unidentifiable substance in it clogging it. After a thorough cleaning, it ran like new..........for a few months and then the same problem came back. He did this multiple times and never found where the crud was coming from so out of frustration, he finally dumped the Edelbrock carb and went back to a quadrajet. So far, no problems on the qjet.

 

[383 240z]

So its the carbs fault he had a dirty fuel system? Keith

 

[Gary S]

So its the carbs fault he had a dirty fuel system? Keith

No, you missed the point. This truck never had any fuel problems with a qjet. These problems started with the Edelbrock carb. They ended when he went back to a qjet. Both carbs ran fuel filters all the time, so it isn't likely that the crud is in the fuel system.
The problem still remains unsolved.
I'm just suggesting that it might be worth pulling the carb and having a look. It might need a cleanup.