Hey guys,

I was driving with my family the other night, first time driving my new 84 long distance (80 miles) out to my moms and back.

I started to notice on my way home that the vehicle seemed to be maintaining speed (almost as if it was on cruise control) even when I took my foot of the gas. The issue seemed to be intermittent.

Well, as we approached a red light I took my foot off the gas and the vehicle kept going! I rode the brake and finally pinned the car to a stop but the engine was trying to keep going! In a panic I threw it in neutral and the engine revved up, the light tuned green and once I let off the brake the car jumped forward!

after a block or so the car went back to driving normal and the pedal response restored.

I've been scared to drive it since then, and I certainly will not be taking my family around in it until I can figure this out.


Do you guys have any ideas? The vehicle had a 350 swap btw.

I don't even know where to start.

 

Put a heavier or extra throttle return spring on it or disconnect the cruise control from the carb or throttle body

 

That simple ?

 

I've had this happen to me before. I was using a vacuum gauge to fine tune timing and I left it on there, well when I hit the gas it slide underneath the throttle and the throttle was stuck at 4800 rpms, wasn't too bad. Just was freaking out because I thought I needed to spend another hour adjusting the carb lol. Check the throttle with the hood open and see if it's binding or if it's not coming back as quick as if should. Really easy.

 

I had installed a new carb and return spring on my swap and found that as the throttle advanced towards the fully open position, the linkage/spring mechanism rotated "over-centre" and wouldn't fully return to the idle position.
I had an assistant work the gas pedal (with the engine off) from the driver's seat while I observed what was happening at the carb. It was plain to see what the issues were (in my case).

 

Could be as simple as a floor mat too.

 

i had the floor mat make mine stick about 3/4 open on me like Scorpner said

 

As our venerable in-house philosopher Sofakingdom says:

Numquam ponenda est pluralitas sine necessitate.
— William of Ockham, c. 1330 AD, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi

Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:

The simplest explanation that fits all the facts is probably the right one.

 

A Old Christine issue....................

 

your signature doesnt' say what your car has. (carb/tpi/tbi, etc) it could be a floor mat. Thats WAY more common that people realize. It could be the throttle cable or the spring. The TPI units on these cars were FAMOUS for the intake getting carboned up and needing cleaning (throttle plate sticks in the throttle body) The carb could be gummed up if thats what you have. It could be the cruise control cable binding up. Shifting into neutral will work in an emergency, but I wouldnt drive it at night, or in ANY kind of inclement weather until you get that figured out.

 

I once had a cruise control that didn't dis-engage when I braked coming to a light. Just revved up to maintain speed. Had to do the quick shift to neutral. Quite scary.