by Barry and Cindy 1997 U270 36′
Our Cummins C-8.3 engine has a fuel shut off activated by a solenoid, which pulls-up with starter and holds-up with the ignition.
We found the solenoid was not opening fully which caused our engine to exhibit low-power and only moved motorhome at low speeds due to fuel starving.
We could remedy the problem by manually pushing up solenoid when the engine was running. A plastic cable tie could assure that the fuel valve stays open, but it will also prevent engine stopping even with the ignition key off.
The solenoid has two internal 12-volt coils. A light magnet force is powered by the ignition key, but the force is not enough to pull-up against the internal spring and injector pump. A very strong magnetic force is powered from the starter circuit, which has enough force to snap the fuel valve open. When the starter motor is disengaged, the light magnet force will keep the fuel valve open without overheating the fuel solenoid. A relay is also used in the circuit.
We removed the original solenoid and mounting bracket and installed a new bracket and new solenoid.
Original Bracket
Original Bracket Removed
New Bracket
Cummins part number 4089574 fuel solenoid kit has all the parts including new attachment bolts. Cost is $300 garage price and about $400 consumer price. The new solenoid is larger and has improved construction.
New and Old Solenoid
It is important to adjust the solenoid pull-up length correctly. Solenoid must be able to fully pull-up its movable core so it will stay up with just ignition coil. And at solenoid fully open position the injector pump fuel shut off valve must also be fully open to ensure full fuel flow from lift pump.
New Installed Fuel Solenoid
New Pivot
Fuel Shut Off Relay Diagram