Hello im new here i needed help with my 2001 ford f350 with the 7.3. My fuel pump doesnt want to turn on when i turn key. I turned it on by passing power and ground directly from the battery and it works great. So then i checked if there was power at the wires that hook up to the the fuel pump and there is one one is ground while the other is power but thats only while they arent hooked up to the fuel pump as soon as i hook them up i loose power it just disappears i dont know what it could be.
any help?

 

Have you checked your fuses?

 

ok i checked that fuse and its fine

 

nothing changed

 

Let me get this straight...if you hook straight from battery to pump you get pump, if you check power and ground feeds to pump you have power and ground, you hook them to pump and you get nada?

 

thats right ive never had that happen to me before its got me stuck

 

Check the quality of your ground, just because it gives you a reading without a load on it doesn't mean that it has enough oomph to run the pump, if that doesn't do it do the same with your power connection.

 

May be a problem with the wire connector at the pump. The PCM turns the pump on by providing a ground to the fuel pump relay. That relay then feeds power to the inertia fuel shut off switch. If that switch was tripped....then you should see an indicator lamp in your instrument cluster. Since you didn't mention that, I assume your inertia switch is fine. Under normal state, the power passes through the inertia switch to your pump and back to the PCM (so it knows that your pump has power). I am not sure why the PCM needs to know if there is power at the pump...possibly so it can control the injectors?

At any rate....all this is fine during the first 20 seconds or so after the key is turned on. If the engine is started in that 20 second window then you are off and running. If the engine isn't started, then the PCM turns off the pump (by removing the ground signal to the relay)

If you have 12v at the Pink/Black wire at the pump connector then that means your PCM is attempting to power the pump. If you verify the electrical connection is good, then check the pump. If the pump checks out good then you might have a weak relay.

Hope this helps. The attached files are for 2000 model year. What year is your truck?

 

Have you checked emergency fuel shut off on Passenger side inside the cab, sits between knee and feet on outside wall?
I think that is what S&B is referring too unless there's something else I'm not aware of...

 

checked the grounds and thwyre fine will have to check the power connections

 

yeah already checked the switch thas fine too

 

Thanks for the diagrams will look into them tomorrow

 

Don't forget to check the actual voltage when testing for power. A bad connection that makes too low voltage might light a test light, but not enough to start a fuel pump.

Good advice coming from the Brotherhood, but wanted to add this note while you're testing.

Good luck!