97 GMC 3500 stalling while running

[Ricky11]

My truck randomly shuts down while running, usually on the highway. It will be running fine then suddenly the rpms go to zero, and it stalls out. After I pull over it starts right up again and runs fine for a while, and then does it again. I had it checked by my mechanic who found nothing wrong with tranny and said the fuel pump was not the issue. I then pumped her full of diesel conditioner/cleaner, and it still happens. Now the truck occasionally won't start at all, unless I put it in park, shift to drive, then try again. I doubt it is the fuel pump since I can rev it up and it doesn't bog down and pulls loads fine without hesitation. Could it be sensor on the transmission?

[p47tbolt]

More than likely you have a faulty injection pump with
the 6.5 turbo diesel.I have replaced a lot of these pumps.And
the fuel system may need cleaning.Look in the bottom of the housing
where the fuel filter goes and check for debris.GM warranty(special policy replacement) on the injection pump is 11 years and 120,000 miles.All the fuel pump(lift pump) does is supply fuel to the injection pump.Once the truck is running the injection pump can pull the fuel itself.If the fuel system needs cleaning,you will have to pay for that.GM will cover the injection pump 11/120,000.