Jon tested the PCM and it tested fine and started his truck ok. While the PCM was gone. I started checking the grounds. I haven't given that any thought since my truck is a New Mexico truck with zero rust. The first ground I checked was the PCM ground. The paint on the fender was not removed and the head of the small bolt had paint on it. So the ground lug was sandwiched between paint. I fixed that and after installing the PCM, it's been starting and running fine.

I would recommend everyone to check their grounds when they have time.

Thanks for the replies and hopefully this will help other?

 

Really, I know grounds are just as important as power side but that is still a little surprising. I can see it effecting overall performance but if it was getting power then it had to have some grounding. Either way congrats on having her up and on the road again.

 

Congratulations on the fix! It is really nice when it is something simple. Too bad you had to send your PCM off in order to find it, but the end result is what you were striving for and that is a good one!

 

Sending the PCM wasn't bad; it's 24 years old. Basically 2 day shipping each way and one day testing. Cost was very economical because no repairs were required.

I did the ground inspection while the PCM was gone. Basically what was happening is there was enough ground for key on engine off testing. But once the engine started turning over and all the sensors were actually operating; particularly the IPR. Then sense voltage was dropping where the CPS signal wasn't sufficient. Once again the CPS circuit is vulnerable IMO.

What tipped me off was when I removed the CPS from the engine and waved a wrench in front. The tach needle moved. If I installed it in the engine and cranked it, no movement. That was dis concerning. I put my bore scope in the CPS hole and could see the cam wheel turning. When I had my engine rebuilt in 2019, I stitch welded the cam wheel to the cam and the gear to the crankshaft. I knew they were in place. Jon was happy to hear that. He stated he has experienced 5 or 6 7.3ss over 500 hp where the cam wheel had walked, Probably from driving a higher load from the high volume HPOPS. The cam wheel and crankshaft gears are both helical cut, so there is more side loading in that situation.

I also tack welded the oil nozzles and tig welded the oil pickup tube on the LPOP.

Wednesday it will be pulling our converted cargo trailer from NE Wisconsin to the Arizona desert.

I highly recommend Diesel Technology.

 

I am glad it turned out to be something simple. I think I will check mine today

You should start a build thread for your truck. I am sure others would be interested to see its progress. How do you like that KC turbo?