Archived Throttle jamming

[Crowhurst]

I am stuck with a throttle problem, and the truck is rapidly becoming undriveable. The throttle seems to jam, and when more foot pressure is applied, the throttle jerks over a hard spot, and then allows accelleration. I have disconnected the throttle cable, and that is working perfectly. I had the recall done on the cable ends about 2 years ago. The jamming seems to be centred on the Throttle Position Sensor. It's either the TPS, or the throttle linkage solid rods below the TPS. I know I should disconnect the rod to isolate the problem, but I am reluctant to disconnect the rod ends as I suspect they are critically adjusted for length in the slot at the rear end. However, when I hold the rod it moves smoothly to open the throttle, so I suspect the TPS. There seems to be a lot of slop, over one eigth of an inch when I waggle with ther lever at the outside end of the spring in the TPS where the lever arm is attached. Is there a bearing at that outboard end of the TPS which might have disintegrated? I spray a lot of contact cleaner in there at every oil change. Might I have washed all the grease out of a bearing, and caused its collapse? I am off the road until this is sorted, so I'd be grateful for any advice. Nick.

 

[Joe G.]

Take the TPS off and see what happens to the jamming problem.

 

[Crowhurst]

OK joe, I'll get at it . Nick.

 

[Bob4x4]

That shaft rides on 2 thinwall plastic bushings. I have seen them wear all the way through and into the steel shaft. If you have a lot of play check it out.



Bob

 

[Crowhurst]

I removed the TPS and the problem continues. It feels just like a throttle cable that has half broken inside the sheath, and is about to break. Just like the old throttle cables on motorbikes. However, with the cable disconnected, the problem remains. I'll see if I can look at this shaft. Thanks guys, I'd be stuck without your advice. Nick.

 

[Crowhurst]

I removed the throttle rod at the TPS end. The TPS is smooth. If I operate the throttle arm lever on the injection pump lever, I can feel the resistance after about 5 degrees of turn. It seems to take up that amount of slack, and then hits a hard spot. Once through the hard spot, the lever rotates freely. This resistance, multiplied by the levers, is what I'm feeling. Is this normal?

 

[Crowhurst]

Fixed, thank you.

I cleaned and lubricated the linkages and theTPS, re-assembled them, and it is unjammed, and I'm back on the road. I don't understand what caused it, and I hope it won't recurr. Many thanks to Joe G. and Bob, from Nick.