I had my holley rebuilt about 9 months ago and it worked great. however i blew thew the tranny and the car sat for somtime. after sitting she isnt the same carb. car runs like absolute crap. horrible hesitation, back fires and i cant get on it or it will just sputter out. i replaced the power valve and put in a backfire protecter kit to no avail. im ready to throw the thing in the trash. do i need to have it rebuilt again? i know its not a timing issue as i have replaced the vacuum modulater, and triple checked all my timing adjustments. thanks for any help.

 

Sounds like an accelerator pump fuel delivery problem.

Look down the carb and see if fuel comes squirting out
with even the slightest movement of the throttle linkage.
It should.
If not it could be dried out parts in the accelerator pump system. Like the diaphram or the check valve in the bowl.

 

I agree with the provious post. Your carburator had been sitting with fuel in the fuel bowl. The fuel eventually evaporated, and the accelerator pump, and possibly other carburator components, may have become brittle. I would suggest another rebuild before you throw in the towel. Those two-barrels aren't that bad to rebuild.

85 Z28 305 Holley 650 Street Avenger, aftermarket muffler, port n polish cylinder heads, gutted cat, no smogs.

 

the accel pump seems to be working top notch. and it is a 4 barrel not two, sorry for any cunfusion there.

 

Bad cap. rotor, plugs, or wires

 

i bet it need a next rebuild. i am hateing on my holley carb to so u r not alone lol.