Engine/Transmission (1998.5 - 2002) Stumped on pump

[Casper69]

Got a stock 2001 high output. VP finally gave up after 260,000 so decided to try an s/o pump. S/O pump came off good running 2001 S/O which had been wrecked. When I put pump on mine and cranked engine there was the normal rough idle and smoking ,except it never cleared up completely. Had intermittent loss of power and throttle response and smoking. It would straighten out some, but engine never sounded just right. Pretty threw no codes on other truck and never missed a lick. On mine there were immediate codes for p0216 and p1690. Pump was put back on other truck and again there were no noticeable issues including codes

 

[PBJ2500CTD]

It is my understanding that interchanging the SO and HO pumps may cause issues. https://www.turbodieselregister.com/threads/220653-VP-44-HO-versus-SO?highlight=so+ho+vp

 

[DonFitzwater]

Buy the right pump, make sure your lift pump is good.

 

[JR]

Are you positive the key didn't roll back when you installed the pump the first time? If not seated in the shaft perfectly it effectively alter your timing. Also look at both keys from each pump to verify they are the same. Should be stamped with amount of offset and arrow which needs to be pointed towards the pump. I don't recall if the keys are different from HO to SO but that is how they are calibrated and why they always come with their own key so you should be using the key from the HO pump.
As mentioned verify proper fuel pressure

 

[Casper69]

Yessir the key was aligned perfectly in keyway. The keys each have different numbers that correspond with the number stamped on the pump housing. Was my understanding you couldn't switch the keys but perhaps that's the step I missed. As for fuel pressure I've got 17-18 pounds. New lift pump. Also , when timing gets off or whatever it is, I can switch key off and back on and full power is restored.

 

[JR]

I just re read my post, I was backwards in thinking you were switching to an HO.... still early in the morning I suppose
At any rate yes you should be using the key the pump came with. I've seen bad fpcm on the VP do the exact same thing you are seeing. At first start up pump runs strong but would get real wacky shortly after. The best step by step troubleshooting on these pumps is over at Blue Chip website. I'd check his page out.

Here ya go

://bluechipdiesel.com/vp44_diagnostics.html