View Full Version : CJ5 w/Buick V-6 will not idle

J Friedrich
06-23-2014, 05:02 PM
The CJ is a 1971. My Buick V-6 will not idle when warm. I have adjusted the idle screws from seated to many turns out with no change. I can hold near idle speed (800 to 1000 RPM) with the accelerator. It will idle at about 800 RPM when cold but once it is warm it dies when I let off the accelerator pedal. I removed the PCV valve, installed a breather cap and plugged the manifold port, I don't know if that would affect idle. I would appreciate any ideas.

06-24-2014, 06:05 PM
Maybe vapor lock, caused by the carb getting to hot, otherwise look for a vaccume leak

06-24-2014, 09:27 PM
Sounds like a vacuum gap is forming as things warm up. Your vacuum gap can cause a vacuum leak causing it not to idle as it warms up. A can of either or WD40 can help find the leak if that is the problem.
Percolating fuel as it goes into the diaphragm of your mechanical fuel pump can cause the same symptoms.Either nor Wd40 will help find this as easily. Heat is the cause of the fuel to percolate and bubbles to form in the fuel line as it gets to the diaphragm of the mechanical fuel pump, causing vapor lock. The secret here is to route the fuel lines away from heat sources as much as possible, trying to keep the bubbles from forming in the fuel lines.
Good luck on this.

07-07-2014, 08:32 PM
I had this issue with my 66 mustang. Bought some fuel line insulation for the line from the pump toothed carb and wrapped the pump. Problem solved.

Old timers say to use a clothespin on the fuel line to prevent vapor lock. Dad sweared by it.