I have a 98.5 24v work truck and when I got in my truck this am and went about 1/2 a mile and the truck died, I got my smarty and it read p1688 internal fuel injection pump controller failure, and P0251 injection pump fuel metering control "A" Ma. I am guessing the the vp44 pump is going out, but when you turn the key on and try to start it it will turn over but not fire off. and then you can leave the key on and still hear the lift pump and i guess it is the vp44 pump by the fuel filter still humming. I just dont want to drop 1500 on a vp44 pump if it is not the problem. HELP

 

The 1688 mean a dead VP.

 

pump is bad. got same promble just got one from blue chip desel.

 

1688 is what I got half a dozen times before mine went to the great VP pile in the sky.

 

Thanks guys I am pretty sure that is what it is also, I just wanted a few more opinions.

Michael

 

the fuel pump control module usually puts out two codes when it dies,1688 and 1689, but either one is bad..........

 

02 2500 4wd all stock. same codes late last fall. lift pump and ip relaced. Started right up and running very good now approx 21 mpg. Have 232k on it and never worked on diesel before. Do the research and read the forums. Also.
Cummins has online quickserve that costs $50. for year where you get most info. by your engine ser. #