Fuel Solenoid not holding open

[34atlantic]

After doing some troubleshooting this weekend I found that if I zip tie the fuel shutoff solenoid open engine stays running. Without the solenoid being zip tied the motor will start I can see the solenoid open but as soon as I release the start button solenoid closes and engine stalls. I have tested the voltage at the 3 wire connector and using the ground (black) and the white when the start button is pressed I am getting 9-10 volts on the white wire. The red/purple with the ignition key in run I am getting 12-13 volts when key is in the run position. Am I missing something wiring looks to be correct. The only thing that I didn’t check is once the motor is running which I would have to zip tie the solenoid open and check what voltage I get on the red/purple. Any suggestions on what else I should look at? I have seen mentioning of a diode by the alternator?

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[dakotasmoll]

Nice job. Following wiring oftentimes pays off. And now you’re a little better-versed in the workings of a cummins!

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34atlantic

[34atlantic]

I believe the 9-10 volts is because there is a slight voltage drop when the starter is cranking over.

When I cut the zip tie the solenoid does not stay open

Tony the magnetic relay is brand new and the solenoid is good.

I have traced the issue back to a wire at the terminal block where it was connected. The way that I figured it out is jumped the pins at the engine harness and was able to get the motor started so I knew that the motor side of the wiring is good with no faulty connections I then connected the purple wire directly to the ignition switches run position and started the motor and it sucked in and held after releasing the start button. I have some work to do on the wiring of the ignition circuit.

Thanks to everyone that chimed in.

[Tony Athens]

Lets “see” the condition of the solenoid & the associated wire at the solenoid and at the starter magnetic relay.. The reason could be there ( high resistance wiring connections) ..

[dakotasmoll]

also…if you start the engine while it’s zip tied open and then cut the zip tie does the solenoid stay open or does it shut itself?

[dakotasmoll]

that’s strange you’re only getting 9-10v…from what i understand the fuel solenoid takes a large amperage to overcome spring and then small continuous amperage to hold it open. i was having an issue of the engine not turning off after turning the key off. i had a bad ground which was allowing small voltage to keep the solenoid open so the engine continued to run. i would check that your plug isn’t shorting across…or if that looks good, follow your wires. if it’s for sure not a wiring problem maybe the solenoid in the shutoff valve has stopped working.

i’ll bet that if you’re only getting 9-10v when the starter turns that there is not enough juice to get that solenoid to suck open and therefore stay open. i’d follow the white wire and check connections, and check that the ground is solid.

[Author]

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