Originally Posted by Canadian Charlie
Here is my problem:
I have a Chevy Silverado with a small block in it and lately the idle has been going from 1000RPMs to 3000RPMs at idle, really jumping around. So a couple a days ago I pull the carb (Holley 750 double pumper) thinking I have a vacuum leak or something. Today i go and remove the fuel bowls to find a brownish sludge in the secondary bowl, the primary bowl is super clean.
What is causing this?
Also on the intake manifold right under the seconday bowl there is a puddle of gasoline. I have to admit that the mounting point on the rear of the intake is stripped so my carb is only held on by 3 bolts
The jets are not clogged
Did this carburetor get cleaned? That gunk is also in the passages and it will interfere with fuel flow and more importantly emulsion.
The idle is way high this sounds like an air leak somewhere. Only three bolts holding it to the intake, the Holley castings are easily distorded often permantly when not fastened at all locations and or with over tightening.