Hello. I have a 1985 with the 300 CI 6 CYC. I just put on a new carb, egr valve, oxygen sensor and did a full tuneup. THE PROBLEM--- The truck idles ok, after running for about 5 to 10 minutes the engine acts like it is missing on 2 or 3 cyclinders or it is running out of gas. If I floor it the truck will take off. After running a total of 30 minutes or more the problem goes away. It seems like when it warms up it's ok. What do you think could be going on? Maybe the fuel pump? Also the fuel filters are new and choke opens wide after a couple minutes of running. Greg.

 

just as a guess...you might have a cracked distributor cap.

when your engine is running it condensates inside causeing the missing. afetr running for a while it dries up.

replace the cap and rotor. and if it has been a while...maybe a whole tune-up

 

OK on the distributer cap. Im going to check it out this weekend. Thanks, I'll let you know what happens. Greg.

 

your truck could be simply cold natured.

 

Maybe your choke is pulling off too soon.


BE

 

Do you mean opening too early? The choke opens all the way as soon as the engine starts. Greg.

 

Yes, thats exactly it. The choke should stay partially on for 3-5min or until the engine can run ok with out the rich mixture. Your carb kit should have some specs on how to adjust the choke to stay on longer. Did you mark the spot where the choke was set when you took it off? If not, the easiest thing to do is loosen the three screws that hold the adjuster, open the throttle with your hand and while its open, turn the choke adjuster lightly until the choke butterfly closes.
BTW this is done on a stone cold engine.
Then tighten your adjuster screws and try it.
Its really trial and error.

BE