Engine won't decelerate on it's own
 

I have driven my truck a couple of times in the past several days and am experiencing this problem:

The engine cranks and initially idles fine. The problem that I’m having is that once I press on the accelerator, the truck wants to stay at that speed/rpm. Even when I want to decelerate, I have to apply the brakes, and the truck still remains at whatever rpm it was running prior to me braking.

If at all possible, I would like to attempt to fix this myself (unless it involves rebuilding a carburetor). Any ideas what this could be and what the fix is?

Any help is appreciated.

Re: Engine won't decelerate on it's own
 

Start by making sure the return spring is attached to the carburetor. It should pull in the opposite direction of the throttle cable.

Make sure nothing is binding the throttle cable or linkage.

Re: Engine won't decelerate on it's own
 

my first guess would be to see if your return spring has come loose or is broken. it should go from the carb to the intake.

Re: Engine won't decelerate on it's own
 

Maybe return spring is broken, or something is binding with the linkage.

Re: Engine won't decelerate on it's own
 

Post the type of carb and engine...

If it just started it could be sticky acclerator shaft. If it's been doing it, then it could be carb adjustments.

Re: Engine won't decelerate on it's own
 

It's a 4 barrel Holly Carbuerator with a 350 Chevy smallblock

Re: Engine won't decelerate on it's own
 

If the suggestions already offered don't fix it, post a pic of the linkage side of the carb.

Re: Engine won't decelerate on it's own
 

Sounds dumb but it also may be the accelerator pedal. On my 68 I installed a new one and it was "getting stuck" due to the bottom of the pedal coming out of the two metal balls that are on the floor. (I was getting the same symptoms) I still can't get it to stay mounted correctly all the time but I just push the bottom back down when it happens.

Re: Engine won't decelerate on it's own
 

I had a similar problem with both the holley and edlebrock on another 350. The holley the problem was the auto electric choke wasn't hooked up and once the pedal was advanced it would hang open thus causing the higher RPM. Hooing up to a switched 12 volt circuit it idles fine. On the other carb the 4 mount nuts had worked loose enough for the carb to shift about a .032 of an inch to catch the rear plate and keep it open. That was on a performer intake. Rule out the springs and linkage first but check proper operation of your coke on the holley. Work the linkage to wide open n release see if everything returns to the proper position. Also Holley's web site does have a troubleshooting chart worth a look also. Good luck.

Re: Engine won't decelerate on it's own
 

Had the truck looked at this morning... The carb needs rebuilt as the gummed up parts are causing the throttle not to go down. On top of that, I apparently have a burned head. I have black smoke from the right exhaust.

Had some money stuck back for a maaco scuff and spray... Looks like that isn't in the cards.

Thanks for all of the responses. Wish it could have been the easy fix.
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Re: Engine won't decelerate on it's own
 

You can handle the carb rebuild. Take it slow. Get that done and then see if you still have the smoke problem. Then work on diagnosing that.
Just curious, how did they diagnose the "burned head"?
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Re: Engine won't decelerate on it's own
 

It was a buddy of mine that is a shade tree mechanic. I believe the diagnosis was due to the smoke coming out of only one side of the exhaust.

Any tips on how to rebuild the carb? I'm not mechanical (at all) and it looks daunting to a novice.
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Re: Engine won't decelerate on it's own
 

Holley's web site has tons of info. Plus U tube. I think they even have a service on their site where they rebuild your core for X number of coin.

Re: Engine won't decelerate on it's own
 

Another option is to buy a carb. It depends on what kind of carb you have. I bought a rebuilt carb for my 67 from Advance Auto and it was exactly like the stock carb. Ran great right out of the box.
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Re: Engine won't decelerate on it's own
 

I had something like this happen the other day. I have a Summit air cleaner and the carb linkage got wedged under the bottom of the air cleaner.

Re: Engine won't decelerate on it's own
 

Pull the carb and try cleaning up what you can see. Spray carb cleaner in there and work the throttle back and forth and see if you can get it to loosen up.
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