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I have a 1992 Ford f150 that will not start. With my code reader I ran a test and code 543 came back fuel pump secondary circuit fault. I thought replacing the fuel pump relay switch would fix the problem but no luck. Can anyone give me some advice? Thanks
I thought replacing the fuel pump relay switch would fix the problem…
Relay switch? Does the fuel pump relay click when you turn the key? Do you hear the fuel pump turn on in that tank? How about the other tank, if applicable.
Do all the usual things.
1. check to see if the inertia switch is tripped.
2. check for power for one second at the inertia switch each time you turn the key to the run position with a loading test light.
3. If 1 & 2 above are OK check for power at the selector switch and see if it is set to the tank you are using.
4. if the switch is OK check wiring to the tank and if that is OK change out the fuel pump module (FDM).