Hard Starting/Surging

[dhmarkley]

Hey everyone, i have been having a problem with my truck. It started with surging (RPM hangs sometimes while accelerating) then whenever i come to a stop and push the clutch in it stalls the motor. Now it is getting hard to start some of the times.

What i have does so far:

Right after i got the truck the IP went out, so i replaced it with a Mech. Marine IP. I also rebuilt the injectors with the marine replacements. The truck ran great after that! Then it started with the problems i listed above, so i thought i would replace the lift pump. it seemed to run a little better for awhile but now it has gotten even worse. The motor stalling is a new problem that just started a few weeks ago.(About 2 months after i changed the lift pump) I have done a full service and changed all the filters with new ones. About the only thing i haven't tried is the OPS, but that is next on my list.

My other idea is that the new High Performance IP and Injectors are too much for a stock Lift pump.

Also my fuel guage just started to act up the past few days. Not sure if it is related or not. (Sending unit was replaced about 2 years ago)

Any ideas? :confused:

1995 GMC K2500 HD XC
6.5L Turbo Diesel
Mechanical Marine IP (3 Years old)
Marine Injectors (3 Years old)
Manual Wastegate (15Lbs Boost)
Pillar Cluster (Pyro, Boost, Oil temp)

[twaddle]

I'd check a few simple things before changing injectors or digging too deep. Can you hear the fuel lift pump buzzing when switching on the ignition, cranking over the engine or while the engine is running. Can you connect up a pressure gage to the fuel system?
Also check for air getting into the system and especially check the suction line from the tank to the lift pump in case it's drawing air.

I had an ex army M1008 with the 6.2 diesel gave me the very same symptoms and it turned out to be the suction hose had been chaffing against the chassis, worn a hole in the hose and depending on how the hose was vibrating or sitting it would work OK then suddenly doing what your truck is doing. I could hardly see any damage but when the hose was moved or shaken a little the engine would change tune.

Good luck

Jim