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General Tech Accelerator Sticking

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KVH

KVH

Obi Wan
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I have a strange problem with my accelerator pedal. Each time I stop at an intersection my RPMs are about 1400. If I flick the accelerator pedal quickly, it drops back down to 900 or 1000, rate rate should be.

I’ve checked the carburetor linkage, and everything is clean and well lubricated. I’ve checked the accelerator spring and nothing‘s interfering with it.

I thought the problem was the carpet getting bunched up behind my accelerator pedal, but that doesn’t appear to be at either. It’s puzzling.

Could it be that I have a bad bushing where the rod goes across the engine bay from the driver side to the passenger side? I tried lubricating that bushing, just in case, but maybe I haven’t done it right.

Any ideas? Thx
 
KVH said:
I have a strange problem with my accelerator pedal. Each time I stop at an intersection my RPMs are about 1400. If I flick the accelerator pedal quickly, it drops back down to 900 or 1000, rate rate should be.

I’ve checked the carburetor linkage, and everything is clean and well lubricated. I’ve checked the accelerator spring and nothing‘s interfering with it.

I thought the problem was the carpet getting bunched up behind my accelerator pedal, but that doesn’t appear to be at either. It’s puzzling.

Could it be that I have a bad bushing where the rod goes across the engine bay from the driver side to the passenger side? I tried lubricating that bushing, just in case, but maybe I haven’t done it right.

Any ideas? Thx
Click to expand...
It appears you have a TR4A. Correct?
What carbs do you have? HS6 or stromberg?
Charley
 
charleyf said:
It appears you have a TR4A. Correct?
What carbs do you have? HS6 or stromberg?
Charley
Click to expand...
HS6s I just spent an hour on it again. It’s a mystery. The little return springs seem to be working, so the sticking foot pedal must be something else, and I’ll bet when I find it I’ll think it was obvious.
 
KVH said:
HS6s I just spent an hour on it again. It’s a mystery. The little return springs seem to be working, so the sticking foot pedal must be something else, and I’ll bet when I find it I’ll think it was obvious.
Click to expand...
I use HS6s on my 3 TRs. One car had this same problem. I used a stronger spring on each carb. To solve the problem. Actually I shortened the spring and bent a new end to make it stronger.
Charley
 
I wish I could replicate a situation where the throttle spindles hang up and then release. That would explain it all, but I’m seeing nothing along those lines. Makes me wonder if a butterfly is catching inside the carb body.
 
For me it was a bent accelerator rod that crosses over behind the engine to the carbs linkage. It would rub and bind on the back of the block during the return to lower rpm’s. Removed and straitened Also lubed the bushings with lithium grease.
 
KVH said:
I wish I could replicate a situation where the throttle spindles hang up and then release. That would explain it all, but I’m seeing nothing along those lines. Makes me wonder if a butterfly is catching inside the carb body.
Click to expand...
You can. Remove the air cleaners get the engine to operating temperature. Using your hands to move the accelerator. Increase throttle and release slowly. You can watch the linkage at the fulcrum. When you duplicate the high idle. Then move the linkage at each carb to see what allows the reduced idle.
Charley
 
This is common to the cross-shaft throttles, and they will all eventually do it. Each bushing has a bit of drag, and by the time the motion gets to the carbs they stick a bit. Is the spring installed on the arm at the right side firewall?
 
Yes that spring is attached. As I work the throttle manually near the left/rear carburetor, I see absolutely no play at the linkage. The shafts rest tightly each time I release the accelerator shaft. There is some slop where vertical shaft meets the throttle linkages but it seems natural, and it’s not ever sticking at the throttle, and there’s no movement after the accelerator is released. Baffling unless there’s something invisible happening.
 
If it's any consolation to you I've been battling this problem for years. I might try checking the cross shaft for straightness and lithium in the cross shaft bushings like Rich suggested.
 
Is there play in the throttle shafts? Grab them each and move them forcefully left and right to see if you have any noticeable play at all.
 
KVH said:
Yes that spring is attached. As I work the throttle manually near the left/rear carburetor, I see absolutely no play at the linkage. The shafts rest tightly each time I release the accelerator shaft. There is some slop where vertical shaft meets the throttle linkages but it seems natural, and it’s not ever sticking at the throttle, and there’s no movement after the accelerator is released. Baffling unless there’s something invisible happening.
Click to expand...
Your comment about the play with the verticle linkage is just the thing I found . That can be overcome with tighter springs at the carbs. Referring to the 2 springs in the pic.
Charley
 

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I had a similar sticking and found what cjd described,lateral play in the shafts caused by wear on the carb body where the throttle stop wears and wear on the throttle stop side .This was not addressed when rebuilder fit new shafts.
I filed the carbs body shaft hole thrust face true,measured the gap,and fit a small shim by removing some material from the throttle stop side,also worn , to pull shafts rearward to center,with minimal clearance for free movement.
The correct location of shaft holes when rebuilding would be better but this worked for me.
I think heavier springs will just accelerate wear.
Tom
 
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TFB said:
I had a similar sticking and found what cjd described,lateral play in the shafts caused by wear on the carb body where the throttle stop wears and wear on the throttle stop side .This was not addressed when rebuilder fit new shafts.
I filed the carbs body shaft hole thrust face true,measured the gap,and fit a small shim by removing some material from the throttle stop side,also worn , to pull shafts rearward to center,with minimal clearance for free movement.
The correct location of shaft holes when rebuilding would be better but this worked for me.
I think heavier springs will just accelerate wear.
Tom
Click to expand...
Yom,
There is a fairly big difference between the H6 carbs and the HS6 carbs in regard to the linkage and wear on the throttle shafts.
Charley
 
Mine are HS6. I’ll try removing air filters and taking a closer look, but I’m sure not seeing any bind up or play anywhere. The PO used a nail instead of a roll pin at the accelerator shaft but even that doesn’t seem relevant. Any wobble is taken up by that stout spring under the rear carb. It yanks it pretty darn well.
 
KVH said:
Mine are HS6. I’ll try removing air filters and taking a closer look, but I’m sure not seeing any bind up or play anywhere. The PO used a nail instead of a roll pin at the accelerator shaft but even that doesn’t seem relevant. Any wobble is taken up by that stout spring under the rear carb. It yanks it pretty darn well.
Click to expand...
The best that I can help is for you to follow post#7 and then #4.
Charley
 
At idle, it requires so little throttle motion to go from 900 to 1400 RPM that it's likely you will never see the difference. I agree with Charley's suggestions, especially using a stronger return spring. These cars just need it.

Also don't ignore the possibility that the pistons in the carbs are hanging up.
 
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