Truck has a split second "hiccup" before WOT. The truck had this problem before I bought it. The previous owner had dealerships replace batteries, a cable, a loose wire, and finally the VP (LP checked OK and not replaced).

When it did it for me, I was pulling a load and I did not stop. The problem got worse until the truck would barely go 50 mph. Dealer replaced the VP after only 3000 miles, I think I killed it trying to get home. LP checked OK, but I replaced anyway with new cummins unit. Truck did it again afew weeks later once on a hill with cruise set. IT only does it when the throttle is nearing the floor. Never did it again, until last week.

I installed the Walbro and gauges thinking the LP was going south on me. I drove the system about 150 miles, no problems, steady 16-17.5 lbs FP. I decided to open it up and go to WOT on the road. Fuel pressure never moved, but at around 2600 rpm or so, it lost power of a split second, I let off, light came on (P1689) no other codes.

Since it did this with fresh VP and LP I am thinking electrical,maybe? Is it possible for me or a dealer to check the wiring from ECM to the VP with some device? Maybe APPS? Maybe the ECM? I think I have other issues besides VP. I don't want to buy another VP for no reason.

HELP!!!
Thanks