The Stovebolt Site Forums The Shop Area Engine Shop gas pedal won't return completely

On a '51 3100 w/216, I'm curious whether anyone else has experienced this problem. My gas pedal won't return all the way when I let up on it, which of course makes it rev like heck when I'm shifting, and just makes driving difficult in general. I either have to reach down and pull it up (fun!) or I can give it a quick push, which loads the spring and sometimes makes it pop back all the way.

The original spring broke, so I've tried 2 different replacements, neither of which is marketed expressly for this purpose. The first spring was too weak, I decided. The next spring is a "universal" spring-within-a-spring. So I'm usinng two springs at once, and they're not strong enough to return the pedal, and this was an $8 spring.

I have checked for physical obstruction, which I believe is the cause, and found nothing obvious, but I need to look again.

Along these lines, my truck has 2 places to attach a spring: one is on the vertical linkage running up to the carburetor (this is where the original spring was and is where I'm currently connecting), and the other is about 6 inches furhter down, on the actual gas pedal linkage. Nothing is connected to it. Can some of you tell me which spring-connection on which linkage your trucks are using?

Thanks for your comments.

You probably have an issue with wear on the throttle shaft and/or carburetor body where the shaft goes through it. Try loosening the screws that hold the throttle plate to the shaft, and tap it gently to center it in the carburetor bore before re-tightening the shaft screws. Make sure the idle speed screw is backed out enough to let the plate close fully before centering it in the bore. If there's any up and down slop in the shaft-to-housing fit, you're likely to be beating a dead horse with your current carb.
Jerry

Thanks Hotrod.

Not what I was hoping to hear, but I'd rather have the painful truth than 'beat a dead horse'!

I'll troublshoot as you suggest. Supposed to get up to 39 today in NE OK, so a lovely day to work in an unheated shop!

Back when these were running up & down the road every day there was a service item for this problem. It was a small spring that hooks over the idle speed screw & hooks on the screw on the air horn. These are still available. When you see the card with universal carb springs at the parts store it has some of these in it. It is a small short spring with a loop on one end & a 90 degree bend with a loop on the other end. This will help it return to idle. Make shure there is no binding in the linkage. There is no adjustment on the linkage so sometimes you have to thread the end of the rod & put an adjustable swivel on it.

Did the problem start after the original spring broke ? Could the gas pedal linkage be bent and dragging ? Could a cab mount be collapsing ? Might be worth looking into .

This happens to my 54. I have to lube all of the pivot joints in the linkage for it to snap out of it.
Scott

In doing some of what Hotrod suggested, I removed the carb from the manifold. While I had it disconnected from the linkage, I depressed the pedal to see how it responded. To my surprise, it did not return completely (I had to pull on the top of the pedal to get it back all the way), so it apparently has nothing to do with the carb itself. I had previously noticed that where the shaft goes through the firewall, it was a pretty tight fit, and on closer inspection it appears this is where the problem is. I don't see any way to adjust the location of the metal flange surrounding the shaft, as it's riveted in place.

It looks to me that you need to take some of the curve out of the rod that goes fronm the accel pedal to the bellcrank to keep it from rubbing on the opening. Are your cab mounts in decent shape? Cab may have settled on one side making the alignment rub.

Hmmmmm.....BowTieTim mentioned cab mounts also. I assumed he meant "carb" mount and dropped the "r". I don't know what a cab mount is, but I'll look in my shop manual then crawl under the truck and take a look. Just guessing, I would imagine it's a hard rubber cushion that goes between the cab and the frame??? Kind of like the cushion you'd hit if you bottomed out your springs??

What's interesting is the shaft appears to be centered in the felt "grommet", but definitely riding low in the sheet metal opening. Thanks for the tip.

Added comment: I see. Page 1-2 of the shop manual says, "The cab is flexibly mounted at four points. The front corners just ahead of the door hinge pillars are bolted through rubber shims to mounting brackets. At each rear corner, the cab is supported by a shackle type mount". I'll go check 'em out!

lube all the pivot joints with w-d and lube under the foot pedal

He meant CAB. If the cab mount or the body itself erodes/rusts away, the cab will fall towards the frame while all the linkages to the clutch, brake and accelerator stays the same. When this happens it puts the weight of the cab on the shafts that come through the firewall, creating a bind.

According to the picture though, it looks like some rod tweaking will fix your problem,
Scott

Yep,I meant CAB mount.Looking at the picture,you could slightly bend the linkage so it isn't dragging or binding.
There is a bolt or cotter key holding the gas pedal to the linkage(Check to see if it is there).under the hood there should be a cotter key holding it in place next to the bellcrank stud in the block.
Take those points loose and pull the linkage out,then you can slightly bend it.Lube all the pivot points including the stud .

I'm pretty sure it's the accelerator rod going through the firewall causing my problem (see picture in post above). I've bent the rod to change the angle at which it goes through the firewall, but not enough. I hate to bend it any more, as there's a weld in this rod, and if I bust it, I'll really have a problem. I guess I'll just use a Dremel tool to enlarge the surrounding metal piece on the floorboard behind the gas pedal, which I really hate to do, since taking a grinder to parts that ought to fit is not how I want to go about taking care of my truck. Thanks for all the input. Even the suggestions that were not the solution caused me to investigate other things and learn more about my truck (I now know what and where my cab mounts are!).