Acceleration Problem
Thread Starter
Intermediate
Joined: Mar 2005
Posts: 49
Likes: 3
From: Anderson, Indiana
Acceleration Problem
I rebuilt the carb (Holley) in my 67 427/390 several months ago. When I put the carb back on it ran great. I don't often get on it hard but a couple of weeks ago I couldn't help myself and dropped the hammer. It ran like a rocket through third but then started to cut out, chugging and sputtering. Now I can drive it and it runs and idles fine but if I stomp the accelerator it cuts out and acts like its out of fuel no matter if I'm driving or sitting still. As long as I press the accelerator down slowly it runs okay. It's when I stomp it that I have problems. I've been told that this could be an accelerator pump problem. If this is the case, I thought that it would have been taken care of in the rebuild. Any thoughts or suggestions?
Melting Slicks
Joined: Nov 2002
Posts: 2,460
Likes: 5
From: Wheaton IL
It could very well be the accelerator pump but you can check the operation easily. You should see fuel squirting out of the accelerator pump nozzles as soon as the throttle is moved. Give the throttle lever a pump like you are slamming the gas - a bunch of gas should squirt out of those nozzles. If not, that's your problem.
Brian
Brian
Race Director
Joined: Oct 2005
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From: Camp Verde AZ
C1 of Year Finalist (performance mods) 2019
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Change your fuel filter. Also, your pickup screen in the tank may be clogged.
Accelerator pump problems are typically manifested by an instant bog, where the engine doesn't seem to do anything at all immediately after the throttle is mashed open.
Your desription may describe elements of both involved, though.
the running out of gas at higher RPM is a sign of a fuel delivery problem. Maybe even a fuel pump. You need pressure and flow from a pump, so you gotta check both.
Doug
Accelerator pump problems are typically manifested by an instant bog, where the engine doesn't seem to do anything at all immediately after the throttle is mashed open.
Your desription may describe elements of both involved, though.
the running out of gas at higher RPM is a sign of a fuel delivery problem. Maybe even a fuel pump. You need pressure and flow from a pump, so you gotta check both.
Doug
Melting Slicks
Joined: Apr 2003
Posts: 2,819
Likes: 480
From: Florida
I'm pretty sure I ruined a good accelerator pump diaphram once by getting GUMOUT spray all over it. It was stiff and would hardly pump anything. Watching for the spray, as noted above, should tell you if that's the problem.
