Shut Off Selenoid test (1996 P30 Chassis RV)

[Vlad_p01]

As a test, I connected my shut off selenoid to some jumper wires and power. It behaved as expected, worked fine. Can it still be receiving a bad signal that is making my engine shut off during idling at a cold starts? Here is my question: what is another way to test my selenoid is function properly on the go? Would it be unsafe to simply disconnect its electrical connection while it’s idling to see if the problem goes away? Or might that cause more problems and codes? Thanks

(I always try to include some visual, hope it helps)

 

[ak diesel driver]

If you disconnect it it will die

 

[Vlad_p01]

Thanks! I’ll have to find other shut off selenoid tests.

 

[Will L.]

By installing that clear line I was talking about, you can have someone crank the engine to start it while you watch. If the fuel is flowing when cranking, the solenoid is working.

The solenoid works by stopping flow from coming out of the ip. When the flow out stops, the engine shuts off. When you send power to the solenoid by key in the on position, it opens the passage to let fuel flow. Key off blocks the passage stopping flow and turning off engine.

If it doesn’t flow, get a pair of pliers in your pocket. Unscrew the solenoid and it will allow flow when cranking/running. Now with the engine running, the way to shut off the engine is pinching that 1/4” return line that should be replaced with clear tubing. You have to pinch it to stop all flow and hold it a couple seconds until the engine stops spinning. Be ULTRA CAREFUL of the engine fan when doing this.

 

[Vlad_p01]

Great. So if I watch my clear tubing while my engine is idling, and when it shuts off (as it currently does), i notice that fuel had stopped flowing in the clear tubing seconds before, I can suspect my selenoid?

 

[snarl95]

No.

 

[Vlad_p01]

No.

Oh I see why it’s no. My fuel return line is after my injectors. Is that mainly why?

 

[Will L.]

No- the clear ip return line could be separated from the injectors and go to the tank by itself to return the excess fuel.

The solenoid stops flow out the ip. That stops new fuel from flowing in which ends the cycle process in the pump. You really have to watch a video to understand how the pump works to get details but basically if fuel can’t leave the return line it shuts down all pump flow.

When you turn key off the solenoid closed the port and stopped the flow.

The injectors have a tiny amount of fuel that has to get back to the tank. They all ties together and into the same line that is already going to the tank from the ip. They could in theory all go back to the tank by themselves- but all going to just one line is far more convenient and less expensive.