Engine/Transmission (1998.5 - 2002) P1688 code on VP44 - what's the cause?

[BrittCook]

Injection Pump Timing Failure

My pump recently died and threw a code "Injection Pump Timing Failure". The pump would work as long as I was accelerating. Once I stopped accelerating, I could only accelerate again after pushing in the clutch and allowing RPM to idle. Then I could accelerate again. I am running an Edge Comp box. Dealer replaced on warranty. This seems to me to be an electronics failure as the pump still produced pressure to run on initial acceleration.

 

[TurboTweaker]

When i taped the pump wire on my truck i made it 2 blocks and locked it tight. That was with a tst pm3. i put a reman on and it had a 3yr/36,000 warranty. cant dissagree with that.



The Fat Kid

Andy

 

[Gary - K7GLD]

"the vp44 pumps a lot more fuel than the stock injectors will ever use, even at WOT. Now if you further increase the amount of fuel and or pressure... . it creates a larger amount of back pressure on the pump. With the larger injectors you eliminate some of that extra fuel/back pressure hence taking some of the load off from the pump and its internals. "



With all due respect to the "experts", it has been my understanding that the fuel return lines from the injectors back to the fuel tank were there PRECISELY to avoid overpressurizing the feed outta the VP-44 - so actual hi-side PSI seemingly would pretty much stay constant, regardless of injector size, and be regulated by the pop-off settings of whatever injectors are being used.



BUT, I've been wrong before... And never had to wait too long to be corrected!