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-   -   What is tripping my relay switch to my fuel pump? (https://www.dieselbombers.com/5-9-liter-cr-dodge-cummins-03-07/128415-what-tripping-my-relay-switch-my-fuel-pump.html)

Ozzy1020 10-14-2015 06:12 PM

What is tripping my relay switch to my fuel pump?
 
I started at the fuel pump testing the system all the way to the Auto Choke/Shut off Relay. I took a paper clip and bridged the hot wires together. The pump worked and the truck started. I then proceeded to replace the relay hoping that it would fix my problem and it didn't. Now I am trying to figure out what is causing the relay to shut down the fuel pump and how to fix it. I have a 2004.5 with a 5.9 that has been recently rebuilt. The fuel system has been modified with the Air Dog lift pump and water separator system, so I know that their is not any water in the fuel potently causing a censor to go off. Does anyone know what I need to do or where I can find some literature to help me?

Jet A Fuel 10-15-2015 09:06 AM

I would say that its in the relay control circuit wiring or the ECM, since you were able to power the pump by jumping the relay with the paperclip. Do you have any other things not working like warning lights that don't come on when you turn the key?

Jet A Fuel 10-15-2015 09:30 AM

2 Attachment(s)
If you bump the key without starting the engine you should get about 25 seconds of fuel pump operation. but if you just turn on the key it will only be about 2 seconds of FP operation.

Here a a couple schematics

Attachment 30482

Attachment 30483

Ozzy1020 10-15-2015 12:07 PM


Originally Posted by Jet A Fuel (Post 1100567)
If you bump the key without starting the engine you should get about 25 seconds of fuel pump operation. but if you just turn on the key it will only be about 2 seconds of FP operation.

Here a a couple schematics

Attachment 30482

Attachment 30483

The schematics are very helpful. Thank you for sharing that. All indicator lights appear to be working, so I'm leaning to a broken wire some where.

Jet A Fuel 10-15-2015 01:17 PM

5 Attachment(s)
Some of the schematics are pretty generic for diesel or gas vehicles. I did notice that the 2005 schematics don't show a lift pump wired to the ECM the same way as the 2004 so there is some chance that yours may go either way.

Attachment 30492

2005 schematics:

Attachment 30488

Attachment 30489

Attachment 30490

Attachment 30491


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