1984 Z28 L69 5.0 HO with 65k miles

When I get up to about 40mph or higher I can let off of the gas and the car will continue to maintain speed or mildly increase for a good half to three quarter mile- then at 35mph it will let off and the pedal will actually release back.

No the car does not have cruise control LOL

We have rebuilt carb, changed everything we could change out and also all of the accelerator mechanisms seems to be working great not sticking etc.

any help or ideas?

 

been checked and works freely and fine

 

--BUMP--

I'm interested in this... my '97 LT1 has a similar issue, but it only happens after its been run for awhile, then shut off, sits, and heat soaks.

 

any help or ideas?[/QUOTE]

As silly as it sounds, make sure the carpet, dash insulation, wiring or floor mat next to the gas pedal is clear. I've personally seen floor mats cause similar problems.

jms

 

I sure wish it would be that simple. All things are clear

thanks for the suggestions though

 

when you accelerate in neutral does the idle come right back down? if not check really good for vacuum leak especially on carb gaskets and intake gaskets, jimmy

 

As silly as it sounds, make sure the carpet, dash insulation, wiring or floor mat next to the gas pedal is clear. I've personally seen floor mats cause similar problems.

jms[/QUOTE]

This is the same thing my car went through...Gas pedal would stay down. Seemingly, my cruise control wouldn't shut off. Might wanna lay on the floorboard & look upwards. I don't even have a floor mat, so I was SURE it couldn't be anything down there.... WRONG!

It turned out the plastic under dash piece, was rubbing hard against the pedal arm, causing it to be held at the deepest point I had pressed it to, or where the cruise control had pulled it down to. Really sucked at red lights. Well, it generally let the pedal come up some, but at idle, 1200-1600 rpms was "normal" for that.

 

in addition to what has been said, 2 other things come to mind, first does the accelerator cable work freely?
when they get old they tend to get sticky. most of the time when they are sticky you can't really tell with your foot by how the petal feels. it happens slowly over time so you normally won't notice it.
the best way to check it is by hand, unhook it from the accelerator & carburetor & see what it feels like, it should move very smooth & easily.

i think this one is more likely, do you have the throttle kicker for the A/C on & hooked up? if so, it may be adjusted too high or wired wrong. also, there may be a short to power that happens only above a certain speed from the wind blowing around in the engine compartment.
if you have a throttle kicker & it is hooked up, unplug it & see what happens.

 

when we accelerate in nuetral it comes right back down

the accel. cable and other things were disconnected and it still did it

 

sounds like the flaps may be hitting somewhere or sticking ( may have a burr on the flap) doesnt take much ,jimmy

 

Mine does this as well , Did you have the Idle put up on the car ? I did so mine does this , I got the Idle fixed and it doesn't do it anymore.

 

If there's a kicker solenoid on the driver's side of your carb, try disconnecting it and see if you have the same problem. The computer momentarily kicks the throttle via the solenoid for 2-3 seconds whenever you suddenly let off on the gas to keep the carb blades from shutting too fast and stalling the car.

 

When the carb was rebuilt, was the primary throttle shaft bushed?