Lean pop
Thread Starter
Drifting
Joined: Aug 2012
Posts: 1,650
Likes: 2
From: Tulsa Oklahoma
Lean pop
I took my car to our the shop I work at the other day and my boss drove it. He said it has something called "lean pop" of course instead of helping me figure out how to fix it he didn't offering advice. So I come to my buddies asking for help!
I just took a spin around the block and if you really try to jump on it, it pops (sounds like a backfire to me) and sputters and almost died. Anything you guys can help me understand about this?
I just took a spin around the block and if you really try to jump on it, it pops (sounds like a backfire to me) and sputters and almost died. Anything you guys can help me understand about this?
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Check the accelerator pump. When you jump on the gas the pump is supposed to give a shot of gas to keep it from going lean and stumbling or popping. Could be the pump is going away, the timing of the shot is off, (or it needs some tuning with a different shooter or cam if it's a Holley). Q-Jet don't have the different shooters or pump cams, but can be tweaked a little.
Thread Starter
Drifting
Joined: Aug 2012
Posts: 1,650
Likes: 2
From: Tulsa Oklahoma
Check the accelerator pump. When you jump on the gas the pump is supposed to give a shot of gas to keep it from going lean and stumbling or popping. Could be the pump is going away, the timing of the shot is off, (or it needs some tuning with a different shooter or cam if it's a Holley). Q-Jet don't have the different shooters or pump cams, but can be tweaked a little.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
engine off, look down the carb. just as you start to move the throttle you should see gas start to dribble out if the shooter nozzle. Front center just below the choke butterfly. If you crack the throttle hard you will see 2 distinct streams of gas directed into the venturis.
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Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
You most likely have a 30cc pump on the primary side. It's a bit of an estimation, but if you press the pump arm without moving the throttle you can kind of guess at how much fuel is being discharged. Then repeat by moving the throttle. Should be about the same amount.
Holley's website has a bunch of info on tuning. Hunt down all you can on the accelerator pump- both adjustment and timing.
Holley's website has a bunch of info on tuning. Hunt down all you can on the accelerator pump- both adjustment and timing.