M1028 starts and idles fine but occasionally changes rpm while driving

[biggestc69]

I bought a M1028 from Boyce Equipment and it starts and idles fine. But every now and again (every couple hundred miles) it acts like the the accelorator get depressed while driving. I dont think that it would be air in the fuel system because it starts and idles great. Maybe lift pump or injector pump going out? I always keep the tank full. I looked through the TM's and could'nt find anything that sounded like problem. Any help would be greatly appreciated.

 

[Barrman]

Fire it up, let it warm up and get off of high idle. Then, use your finger or a screw driver and push the throttle lever up a little. Then hold it. Hold it for at least 30 seconds. I have one that once I am steady for a while, it will start to race up in rpm even though I haven't moved. 27 year old IP. Time for a new one.

If that doesn't happen to you, lift up the front tires and see if they spin freely. Start the truck, apply the brakes and see if they still spin free. I am thinking a caliper that is getting grabby and maybe when it releases, you think you have more power.

Just throwing some ideas out.

 

[biggestc69]

Thanks Barrman! I will def check that stuff out after work. I was also thinking that maybe the trans is downshifting because thats what it feels like but its hard to tell. It still has all the old rubber vaccum lines and being from the dessert I'm sure they are probably shot.

 

[RetiredNavy]

biggest, what did you pay for it at Boyce? IMP has a M1009 for about 4G's or so. Wonder what other issues might be in store.