Info: 1996 GMC Forward 6 Engine: Isuzu 6HE1-TC Engine Capacity: 6 cylinder 7.1 liter diesel Very hard to get info on this refuse truck for obvious reasons. I did note a member once claiming he knew about the 6HE1 engine. His name was Nick Bowers. Here’s the situation. I was asked to go look at this refuse truck as they had an injection pump from a GMC dealer installed new & the issue still remained. Truck starts up & idles. You can throttle up & down. I adjusted throttle so it was at 1700 rpms and let it stay that way for 10 minutes. Then tried throttle up again, to see if it was fuel delivery. Worked fine. No codes lit up that I can see. Problem: When you lower the cab back over engine, get in cab, put in gear and start to drive, it makes it a few hundred feet then bogs down & wants to die. If you quick switch to neutral and throttle up, she comes back to life. Any thoughts on what might be causing issues. if any other info is needed, I’ll provide.
Sounds like it is running out of fuel under load. It takes a lot more fuel to pull a load at 1700 than to just idle at 1700. You did not mention if you had changed any fuel filters. Or the condition of the hoses.
I did change the filters, I checked the screens inline also. I did not check/change the rubber lines. I will try this tomorrow.
I work on stationary engines so this is easier but to test for fuel restriction I would run the return line to somewhere visible and then apply load and the stream of returned fuel should remain full. If it dwindles away to nothing that means the pump is using all the available fuel and then some, and you have to go find a restriction wherever it is.