ive been having trouble for the last couple weeks getting my truck to idle.

One day it'll be idling at 600 rpms, the next 1000 rpms, then itll decide to idle around 1500. Engine temperature doesnt seem to effect it, nor outside temperature. I've checked for vacuum leaks using carb cleaner and noticed no change in idle. Plugs are a even tan color in all cylinders. The brakes are soft when the truck is in its low idle phase and the carb does not respond to adjustments. I rebuilt the carb about 5000 miles ago and all has been great until now.

Any ideas where to go next?

 

Sounds like a return spring/throttle linkage problem. Check the linkage and make sure it moves freely and that the spring really snaps it back down to the adjuster screw/stop. If that is all working properly, maybe the choke is sticking closed (high idle) sometimes and not closing at all (low idle). Once you figure out the problem go through this process if you haven't already:

https://www.yotatech.com/forums/f120...2-36-a-240521/

 

I removed the return spring and unhooked the throttle cable. The linkage is smooth and doesnt bind. butterflys are closing properly and the choke is wide open once warmed up. It drove fine to work last night,no issues, but this morning didnt want to idle and was surging when i would try to hold it around 1500.

Im wondering about the fuel pressure possibly.. Im running a Purlolator/Facet fuel pump. It makes me wonder if its trying to flood it out, but then again the exhaust smells normal...Im going to order a Holley regulator today.

 

I believe the weber carbs have to have a regulated fuel pressure of around 3 psi.

http://www.jeepforum.com/forum/f8/we...n-line-684643/

https://www.yotatech.com/forums/f123...e-here-224965/