Idle problem on C15 261 CU IN

[Phil Waterman]

Hi Terry

Everyone is hitting the most likely cause for lopping at idle, so you have a long list of things to work through. To add to the list what do you have for fuel pump? As Bob suggest fuel flow and pressure are also possible causes. Air leak in can be one of the hardest to track down. I had air leak at the fuel selector valve that took forever to find.

Reason for asking what do you have as fuel pump, is mechanical pumps can have problems at low RPM if the pivot points are worn, or valves in the pump are not sealing, fuel pressure gage should help ID those issues. Electric pumps seem to be more bothered by air leaks on the suction side. One quick check I've used is installing a section of clear tubing just before the carb, looking for air bubbles.

Keep us posted on what you find.

Cheers Phil