Hello I have a 2001 HO, 6 Speed, 24 valve, currently all stock, except for lift pump.

I have recently replaced VP44, got the dreaded code and no start, cleaned fuel tank and lines, filter housing, replaced filter, installed a FASS lift pump.

I have 10 to 12 lbs pressure before the filter, with my foot in it all the way and 8 to 10 lbs after the filter.

This problem was happening before the pump died, but I though it was just the pump, now that the pump has been replaced, it is still happening.

What is happening is that while driving at 50Km/30MPH or better the truck feels like the fuel is shut off for just a 1/4 of a second, it happens about 2 to 3 times a minute and then goes away for 30 minutes then starts again then goes away, then starts again. It is completely random timing on when it happens, if when it happens I stomp on the fuel it immediately starts accelerating.

I suspect it is related to the throttle possition sensor but not sure, anyone got any suggestions? And if it is the TPS or whatever it is called on this motor how to fix it.

Thanks Walter

 

24v have an APPS

from another thread.. ---Did you recalibrate the APPS ? It's just disconnecting both neg. Battery cables for 30 mins, then connect them again. Turn the key to on position ( don't start) and depress the accelerator slowly and then lt off slowly. Start the truck .

 

If the fuel pump is momentarily shutting off then the fuel pressure gauge should reflect the momentary drop in pressure.

What code did you get?

Have you checked for loose connections on all major fittings/connections and grounds.

 

Yes the fuel gouges show no change so I'm pretty sure it's not that, but that is what it seems like, I checked everything electrical, and physical I could and it all seems ok, I will try the apps reset and advise

Sorry it was the 1688 code I believe

 

Double check that code for us please, because 1688 is not a good code to have.

P1688 - Internal Fuel Injection Pump Controller Failure