Fixed everything !!!!???,,,,still misses :-(

[dstoops]

1995 6.5 TD engine R/B 4000 miles ago, BD chip, 18:1, 97 cooling, bored .030, K+N, 4" pinnacle exhaust, new lift pump, R/B injectors, new Heath relocated FSD.
Symptoms:
It will run good until I floor it then will start to miss at around 2000 rpm. If I let up on it it will continue to miss for 20-30 sec.s then smooth out. It seems to be worse when it's warmed up. I took it to a local mechanic who specializes in diesel p/u's. His findings so far have him perplexed:
13 volts to lift pump during cranking but they drop back to 9 during run.
The PCM shows the trucks speed to be 174 mph and rpm's to be 8100 while setting still. It shows engine temp to be 240 degrees when engine is cool but it shows that the temp is dropping as the engine warms up. It seems to be trying to shut the lift pump down in response to these parameters, thus the reduced voltage to the lift pump.
We are suspecting the PCM is the problem. Could it have been damaged when the engine was removed for R/B?

Any ideas would be appreciated...We are stumped!!

[More Power]

Dean,

The lift pump is powered by the "lift pump relay" while you're cranking the engine, and by the oil pressure switch when the engine is running.

So.... It appears that your oil pressure switch is causing the voltage drop.

Try powering the lift pump directly, then test to see if the engine still misses at WOT.

As far as the other bizarre sensor readings... You may have a bad engine ground, loose wire or some other electrical connection that was disturbed/damaged/not reconnected during the engine R&R.

Let us know what develops....

MP

[whatnot]

First, I would make sure his scan tool is set to the right year and engine vin. If it is then I would check to make sure someone didn't change the computer from a different year.

You can unplug the wires to the OPS and jumper the two outside pins together to make the fuel pump run continous. If you test drive it this way and it makes no difference and/or the voltage stays too low then it probably isn't the OPS.

[dstoops]

Thanks to all of you for your responses. I faxed them to my technician. This
prompted him to try another scanner on it and the readings were normal. It
seems that he subscribes to a tech service that provides him with schematics
etc. and the one he recieved for my truck mis-labeled the lift pump wiring.
The bottom-line is that my new OPS was faulty. It failed with less than 4000
miles on it. He installed a new GM OPS that is supposed to be a newer
design. It runs great.
Thanks again guys!!!
Dean