So as you can tell from the subject I’m having trouble trying to get my truck to idle regardless of whether it’s cold or warm.
To give you a little background, I had this truck stored inside for the last 5 years without being started. After a new battery, pouring a little gas into the carb the truck fired right up and ran like I parked it yesterday (even with the old gas). Since this initial startup after sitting for 5 years I ran it two other times with no issues around the farm after adding 5 gallons of new gas to the tank. About a week later I started it up to pick up firewood around the edge of my field and it ran fine and then all of the sudden it wouldn’t idle. It was idling fine and then it was almost like if I had kicked down the fast idle cam to unchoke it but it wasn’t choked at this point. I do know some of the gas was old and rust colored from the see-through inline gas filter. So far I’ve changed this in-line filter (made no difference), took out and cleaned the filter screen, which was very dirty, from the Holley 4150 4bbl carb (made no difference), I then disconnected the rubber line from the gas tank and connected a longer line directly into a 5 gallon gas can of new clean gas (made no difference). I did not adjust anything on the carb as the truck starts right up and runs great as long as you are giving it some gas. I’ve had this carb on since 1998 and have never had to touch it. I’m at a loss as of why it will not idle. Am I missing something? I appreciate any help.

Thank you,
Jeff

 

Sounds like a little piece of junk has found its way into the idle circuit in the carb.

 

Is this something I can easily fix or does it entail a rebuild on this carb? Can it be done with the carb on the engine or do I need to remove it?

Thank you

 

I agree. You will need to remove the carburetor, disassemble it, soak all the parts in a chemical bath, and rebuild with a new kit. If it has sat for a few years, then there's no question.

 

Sometimes you can rev up your engine and smother the carb with a rag and the vacuum will pull the piece of crud through the port. If it were
my truck I would clean the tank and lines out really good and remove the carb and rebuild it. Good luck.

 

On mine (78 F250) the idle deterioriated over a period of months. Gumout carb cleaner would help it for a while... but not long. A rebuilt carb (for the 35 YO original) fixed 80% of the problem. Tune-up with plugs, wires, cap, rotor helped some more. Replacement of iffy vacuum lines got it to 100%.

A can or two of Gumout may help but agree you probably need to rebuild or replace the carb. Its also a good idea to replace all sections of rubber fuel line. With time and alcohol the rubber dries out and can crack and let air in or get really soft when wet with gas and collapse under fuel pump suction. I wouldn't replace/rebuild the carb until you get all the old gas out as a minimum.

 

I would check for vaccumn leaks as well, especially on the port on the front bottom of the carb. It's possible the lines/ caps are dryrotted and have cracked under vacuumn.