Cm875ism hard start after long park

[wellrun]

Cummins ism cm875..CRANK BUT NO START after a long park...overnight or more...it starts easily with a little spray of bagon and will take long to start if not shutdown for hours.... change fuel lines etc

[Lonestar10]

starter cranking at correct speed? low compression? or fuel system loosing prime.

[wellrun]

Cranking speed seems fine... builds up oil pressure

[Lonestar10]

oil pressure means nothing if it has poor compression and the ether helps it spin a bit faster to take off.

[Chamberpains]

Sounds like your fuel system is losing its prime. There is probably an anti drainback valve or check valve somewhere that isn't working properly. I don't know anything about the cm875. Have you gotten on to https://quickserve.cummins.com/info/index.html and registered your engine? Its free. It has all kinds of helpful info directly from the manufacturer of the engine.

[Moose]

Could be losing prime, could also be a weak solenoid, weak CELECT pump or sticking shutoff valve. you need to mechanically monitor your rail pressure during cranking and while running.

Will it act the same on the tank plumbing as running it out of a bucket?