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ok I bought a 1990 f350 with dual tanks 460. Heres my issue. I changed out the fuel relay and I have no power to the fuel pumps. I pulled the relay off the tested all the terminals there is no power to them.
Where is the fuse for the fuel relay located? would the ignition switch in the column cause this? thanks!
Did you check the inertia switch? The one that trips if you get into an accident. Not sure were its located on that truck. I know some of them are near the glove box.
"I changed out the fuel relay and I have no power to the fuel pumps. I pulled the relay off the tested all the terminals there is no power to them.
Where is the fuse for the fuel relay located? would the ignition switch in the column cause this? thanks "
I would start to see if you have power TO the relay. My 94 is located to the right of the fuse panel on the drivers side on top of inner fender well. I just went thru this and found a wire to EEC had corroded - UNDER the fuse panel .... having wiring diagrams was essential .... the inertia switch is between this relay and the fuel pumps ...
The inertia switch is between the relay and the fuel pump. If there is no power at the relay, it's not the inertia switch. There is a fuel pump control wire in the diagnostic connector, which can be jumpered to the signal return wire, also in the diagnostic connector, to force the fuel pump relay to energize. This will help determine if the relay is working properly or if the problem is somewhere else. I don't remember for sure, but I'm thinking that the EEC relay feeds one wire on the fuel pump relay, so check the EEC relay too.
I agree with EPNCSU2006 post. It seems like you really need a wiring schematic to determine which terminals are supposed to be hot with key on. Yes I agree, check EEC relay hot wire as well. Does your engine light illuminate with key on ? Mine did not, and from memory that was my problem, rather than the fuel pump relay wiring. Could be any of them, since you are in the relay box, check both of them, go from there. Good luck.
There is no fuse for the main power to the relay. It is a Yellow 14 gauge wire that connects to the power terminal on the starter solenoid. There is a 20 gauge fusable link on fuel relay power wire, at the solenoid.
The Dark Green/Yellow is the fuel relay out to the inertia switch.
The Red is 12v+ from the EEC power relay for the fuel relay coil. It will be powered with the ignition switch in the Run position.
The Light Blue/Orange is the signal from the EEC to the fuel relay coil.