Need help with an ISX 600 Cummins

See if there fuel leaking from the electric fuel pump. This means the fuel pump is also sucking air. Check to see if the electric fuel pump is also running for about 2 minutes at key on. Sounds like it may be running out of fuel from loosing its prime.

 

Make sure it does not have a timer to automatically shut the engine after 3 minutes. If that is not the problem you may be sucking air through a faulty gasket and losing prime. Look around the filter to see if it is leaking fuel . If you have a newer type see through bowl it may have a hairline crack in it causing the problem too.

 

The fuel is bleeding back, My 2000 Pete with a 600 started doing this and I found a leak at the "T" in the return lines repaired it didn't really help stalling problem but did help MPGs a little. It got so bad that I had to use the manual switch on the front of the pump( the auto start pumps didn't make it to Petes till '02 I think) to prime it enough to start it. I'll spare you the list of parts I threw at this truck trying to fix it, bottom line is there is a check vale inside that pump that is letting the fuel leak back, at that time you could not just replace the pump you had to upgrade to a auto start pump (780.00 USD + labor).Since I never had to use the pump until it started leaking I just took it off completely and put an inline check valve in its place.Worked fine for me for 4 yrs and as far as I know the new owner has had no problems at all(he has had it 2 yrs now).