Car surges when let off gas

[CMB]

Surges probably is not the right word, but when the you let off the accelerator to shift, the car jerks, as if you were in too low of a gear. Is it related to the fuel cut system in the carb? Anyone else experience this?

[Petros]

there is a vac diaphragm connected to the throttle shaft opposite side of the throttle cable side of the carb. It prevents the throttle from slamming closed when you let off the gas between shifts, and reduces tendency to spike fuel/air ratio. Try backing the adjusting screw off a turn.

also, make sure all your vac lines are in good condition (no leaks) and routed correctly. I do not think the fule cut off solenoid would cause this, easy test is to unplug it and see what happens when you drive it (usually means it drives and runs but engine dies at idle.)

good luck.

[CMB]

Thanks petros. i did try the disconnecting of the fuel cut solenoids, and it did not make a difference. I played a little with the diaphragm that you mentioned. I will try some more. I have gone through the vac routing meticulously and checkde for leaks yesterday with a can of carb spray, so i think vac leaks can be ruled out, but there is always a chance I am reading the vac diagram wrong. I will stare hard at the routing diagram one more time. I was hoping the sysmptoms pointed to a faulty piece in the carb or carb accesories. I feel like I am so close to having this car running great, but it is really annoying to drive as it is with this particular problem.

[ARCHINSTL]

Presuming you have a Federal vehicle - did you look at the color-coded vacuum line sticky in Repair Guides?
Tom M.

[Petros]

you might also see if the AAP is leaking fuel into the intake manifold, sucks more gas in when vac is high. just pull the vac line to it and see if there is fuel in it. If so plug it and see if the problem goes away.