Stiff accelerator pump

[V12T]

Had problems cold starting my 512 sixpack and hesitation on acceleration. Discovered that the accelerator pump arm on the middle Holley is so stiff that the tab from the throttle mechanism has bent to the point where the pump isn't being operated. Still pumps (then starts) with strong manual pressure on the arm. Before I strip it down has anybody had this and what causes it? What spares should I get before stripdown?

 

[Ricks72Chlgr440]

Had problems cold starting my 512 sixpack and hesitation on acceleration. Discovered that the accelerator pump arm on the middle Holley is so stiff that the tab from the throttle mechanism has bent to the point where the pump isn't being operated. Still pumps (then starts) with strong manual pressure on the arm. Before I strip it down has anybody had this and what causes it? What spares should I get before stripdown?

Liquid is not compressable so there is a blockage. Need to pull the carb and then the bowl. Get a fine wire and go thru the acc pump orifice. Pull the acc pump nozzle and pull out the checkvalve. Think you will find it is stuck in there due to corrosion. Poke your wire thru all passages and the nozzles. Clean things up and get a new pump diaphragm and reassemble. That should do it.