I have a 2004 F250 Super Duty 6.0L with a Fass Titanium series pump. About a week ago I was driving on the highway when the truck all the sudden shut off. When I got out I noticed that I could not hear my FASS fuel pump running when I turn the key to where it usually starts to pump. I assumed the problem was a faulty pump as it has been louder than usual and just sounding like general ****. I got a new fuel pump and went to install it but when I tested to make sure I had power coming to the pump, I noticed I have nothing. I have power coming off of the battery, through the wiring harness fuse, then out of the relay, but nothing at the pump. I've already uncovered and traced out the entire wiring harness to make sure everything was in good condition and it is. I have also replaced the relay.


I have this other junction that the harness runs in to (see picture below) and I cant tell where the other wires lead to. I have also checked all of my fuses for the fuel pump, ignition switch, and the run/start power circuit and found nothing blown there. I'm at a loss now for why I don't have any power at my pump. Has anybody ran into this issue before? Is there something else I need to check or something other than the fuel pump harness that could be causing this problem? The junction pictured is located directly under the drivers seat. One line coming into it runs from the relay of the FASS wiring harness and into the junction. Then I have a line that runs off of the junction, up along the firewall and I am unable to trace out where it goes from there. I also have an additional set of wires that comes off of the FASS harness relay and runs parallel to the ones that lead into the junction, but this set goes all the way back to the pump and have no power coming through.

 

Keep in mind that the pump is only supposed to get power for 2-3 seconds at initial power-on. After that, the engine must be firing in order for it to begin receiving power again.

Did you check the inertia switch?

What are you calling a "FASS"?

 

I have not checked the inertia switch. I'll check that when I get home today. FASS is the after market fuel system I have. When I said "FASS wiring harness" I was referring to the harness that came as a part of the fuel system.