HELP - NO VOLTAGE

I have a 2004 Dodge 3500 with the factory turbo Cummins in it. We have determined beyond any doubt that there is no voltage going to the injectors during either cranking or running. We fogged the intake and it will fire on ether and W-D. My question is - can we splice a relayed-key on 12 volts to the injectors since they actually are triggered by a ground from the crank sensor via the computer?

I am told the computer operates at 5 volts, so we would cut the injector wires and splice direct to the injector wires to avoid any possibility of reverse feed to the computer. We have also verified that we have fuel to the injectors via aftermarket lift pump and rebuilt CP-3.

The crank sensor pick up module-pressure sensor and pressure/return valve have also been replaced. The batteries are up and the computer relays code to a reader.

Unkl Al Via Email

First, the high-pressure common-rail fuel injection system used by the 2003+ Dodge Cummins is a complex computerized system. The “voltage” seen at the injector electrical terminals is actually an electronic signal that can't be properly examined using a simple voltmeter. If the injector signals were analyzed using an oscilloscope, you would see long periods of no voltage framed by periodic spikes indicating when the computer is calling for fuel delivery. The injectors incorporate high speed solenoids that control timing and fuel flow. By using a scan tool and the on-board diagnostics, available through the truck's ECM, you should be able to identify the cause for any no start – or at least narrow the possibilities. I would not jump any voltage to any expensive electrical/electronic part.

The scan tool should tell you what the fuel-rail pressures are. This is the best indicator for whether or not fuel is making its way through the fuel injection system. Also, from your email I

can't decide whether this problem occurred after a part replacement or if the problem occurred on its own. Either way, let us know what develops or if you need anything else.