new guy with unplanned acceleration question

[pistonium]

Hello All - I've been lurking here for a while....have had a civilian 6.2L pick up for a couple of years, got a 1008 a couple of months ago and that's my daily driver now, got a 1009 a month ago, and that's awaiting an NV4500 swap and restoration. Had Chevy's of this vintage since I got my first truck in late 70's.

I've got a question about my 1008 - I first noticed this problem rarely: when coasting down a hill, an almost undetectable, occaisional, and shortlived acceleration of the engine was occuring. Now it's getting more common, and now happens sometimes when I'm running at steady speed with constant pressure on the accellerator pedal - the engine just speeds up by itself - quickly and a couple hundred RPM. It always slows down if I change the pedal position, and when I'm coasting down a hill, it never sticks at a high RPM. It did this once when stopped at a stoplight at idle too.

I've searched the manuals and the CUCV site and didn't have any sucess at tracking any similar threads or info....but I know it can be had to find things with the search engine here....I would be glad for some pointers to get where I need to go if someone thinks there is some existing info on the problem....

Thanks much -

 

[dstang97]

The only thing I could think of is maybe your High idle is kicking in and you have a bad sensor.

 

[combat jump]

Piston,

I have noticed a similar thing with my M1028. Very slight, and only when decelerating from the highway. I suspect the injector pump will need a rebuild at some point.

 

[Milbikes]

I had a similar issue with my 6.5 diesel. In park, I tried holding the throttle at 1,000 or 1,200 rpm, and it would 'run away' and speed up uncontrollably. It turned out to be a bad injector pump. I don't know how different a 6.2 is.

 

[cjtroutt]

Its time for an IP have yours rebuilt you will have less of an hassle.

 

[b4thundr]

The fiber ring in the pump is breaking down. the rivits are chucking in the pump thats when you get the little bursts of power going down the hill. when the ring is gone, the rivits will break and the motor will run away, the crank will stay in the motor till about 6 grand or so, chech this out pics included....... http://www.steelsoldiers.com/cucv/56488-injection-pump-rebuild-some-pics.html

 

[b4thundr]

also page six in this thread.... http://www.steelsoldiers.com/cucv/41774-m-1031-farm-contact-service-truck.html

 

[b4thundr]

more info.... http://www.steelsoldiers.com/cucv/60942-engine-noise.html

 

[pistonium]

thanks to all!

Well I guess the IP is the culprit....time to pull it for replace (I've got some spares) or rebuild.....

Thanks for the help and confirmation of what's going on -