Originally Posted by kyle86
This problem has been anyoing me for a while. Holley 4160, 80508 750cfm vacuum secondaries.
It is intermittent. If i crank the car up, I usually have air in the acc pump. I pump the gas a few times and then it's clear and works fine. Same happens if I'm cruisng for a while and then pull over, if I pump the gas, it stumbles, but once the air is out, it works great from there on. It's like air slowly gets in it when it's not in use.
I've already changed the acc pump gasket and umbrella valve. Not sure what it could be now.
Check the flatness of the castings of the main body and the metering block in particular. These often warp, when rebuilding with fresh gaskets, early on things appear normal, but as the gaskets flexibility ages away then tiny air and or fuel leaks develop.