Engine revs when clutch is depressed / in neutral... Ideas?

[Rocket600R]

This just started happening tonight. I was driving down the road, pressed the clutch in to shift to 3rd and immediately noticed something wrong. The engine revved to 2k rpms and I felt I slight vibration coming from the clutch pedal. When I put it back in gear and let the clutch out, it goes away and drives normal. When I put it in neutral it revs again...

Can anyone help me out?!?

Truck is a 69 w original 302.

 

[Viperwolf1]

Is the throttle linkage moving in relation to the motor/body movement when the clutch is pressed. That's what the original linkage contraption is supposed to prevent. A throttle cable can prevent that.

 

[Rocket600R]

Not sure I understand.... It will rev at a dead stop in neutral.

 

[carter2772]

carb or efi? Vacuum leak? Electric choke malfunction ?

 

[TAC71]

When in neutral is your foot off the clutch? My first thoughts were body mount flex when using the clutch (common Bronco problem) that pulls on the throttle linkage. Another thought would be a vacuum leak/cracked vacuum hose.

 

[TAC71]

Forgot one thing, is the throttle linkage sticky?

 

[Rocket600R]

Think it may be a sticking throttle linkage... Will investigate more tomorrow when I have some more time. Thanks all!!

 

[Rocket600R]

Think it may be a sticking throttle linkage... Will investigate more tomorrow when I have some more time. Thanks all!!

Dumb question: if this is the case, what is the best way to remedy?

 

[blubuckaroo]

Do you have a body lift? I ran into that with mine. The throttle linkage can be overextended and bind up. Try lengthening the throttle link to the carb then readjust the idle adjustment.

 

[DirtDonk]

The simplest and quickest "fix" for a sticking throttle linkage is at least to try the carb-cleaner, then WD-40 method.
This won't fix a wonky linkage though, just a stuck linkage.

Make sure to spray the passenger side choke linkage too. You might just have a choke that's at the ragged edge of the transition between one step and the next on the high-idle cam.

Is the return spring still intact?

So what if you just sit there in neutral with the hood up, watching what's going on?
Does the engine move in the cradle? Does the body move? Does the clutch linkage hit a wire that is related to the ignition?

What year is your Bronco?

Paul

 

[.94 OR]

When I did my body-off, I was not aware that my front drivers side cab mount was busted loose. When I used the clutch it would actually deflect the body and alter the use of the clutch and possibly the throttle (20 years starts to tarnish the memory). Just another thought.