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Discussion Starter #1

64must
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Discussion Starter • #1 18 h ago
My 1964 1/2 289 mustang starts and idles ok. It backs out of the driveway ok. Accelerating slowing the car is very jerky. Stomp on the gas pedal and it takes off quickly and smoothly. The car has a fresh tune up as well changing the fuel filter. Couldn't see any "floatie" in the fuel canister either. Any ideas?
 

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Keep stomping on it!

Do you have an auto or manual?
 

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Accelerator pump. If this is a new thing, then you probably need to replace the pump diaphragm. If it's always done this, then verify you have a healthy shot of fuel when working the throttle, and it may need more.

What carburetor is on the car?
 

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Too much timing will cause that "jerkiness" too.
 

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A small vacuum leak will cause this too. The bit of extra air causes it to run lean and it bucks at low throttle. Runs fine at higher RPMs because you're giving it enough gas to overcome the lean condition. Check your intake bolts to make sure they're all snug.
 

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Discussion Starter #8
A small vacuum leak will cause this too. The bit of extra air causes it to run lean and it bucks at low throttle. Runs fine at higher RPMs because you're giving it enough gas to overcome the lean condition. Check your intake bolts to make sure they're all snug.
would a Ford toploader have anything to do with the low speed jerkiness? I've only driven my toploader and not anybody else.to compare.
 

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I haven't driven a car with a top loader before, but I doubt it.

I think you'd find tons of 'here's how I fixed my toploader' problem threads if that was the problem.
 
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