Erratic fuel pump relay

[mikeinpa]

Ok, so Im on my third fuel pump relay. Sometimes when shutting the engine off it works as it should, sometimes it "hangs" for a few seconds (1-15 sec.), but lately with the cold weather Ive had to resort to opening the hood and giving it a whack bafore it will disengage. All wiring seems intact (at least what I can see).

Im getting very tired of this and was considering installing a switch to cut the power to the relay from inside the truck, almost like a kill switch or anti-theft switch. Does anyone have any comments regarding this mod? Is this a bad idea? Is it inspection legal in PA? Also, If you happen to know which wire I need to install the switch in it would be a great help.

Thanks in advance...this forun is great!

 

[Opera House]

You might want to check

The fuel pump current. You can pull out the fuel pump fuse and read the current there with a DVM. Current should be between 4 and 5 amps. The pump may have a partially shorted armature which still works but draws higher current. This causes the contacts to weld "on make." This line is fused at a much higher current than the pump usually uses to make it more reliable. The pump could easily draw 3 times the current and not blow a fuse.

 

[mikeinpa]

thanks opera house...I will have to check out the current across the fuse. Im getting really frustrated with it. DOnt know why ford decided to make this circuit "always hot". Guess it was one of their "better ideas".

I still kinda like the idea of a hidden switch to kill the power to this circuit to prevent theft or in case of emergency. Any thoughts? I would have to us a switch with some sort of flip over cover to prevent accicentally turning off of the pump at highway speeds.