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F250 1987 4wd 460ci carburetor. Have power to front pump no power to back pump. Need help to figure out problem. Could it be the dash switch or the valve on the frame? Only have two low pressure pumps and the front one has power back one not. Wiring issue? Relay issue? Driving me crazy I have bypassed the oil pressure switch so I can get power to the pumps with the key on for testing just need to know where to start.
Thanks for the response... don't the wires on the valve run each pump depending on switch location or is the valve just switched by pressure from the pump? It looks like the wires to the valve come in and then back out to each pump.
No, the wires from the valve to the tank are just for the fuel gauge.
Originally Posted by hbphc34
depending on switch location or is the valve just switched by pressure from the pump?
Pressure from the tank pumps has nothing to do with any switching. The valve has a motor in it that is operated by the switch on the dash. When the motor runs it switches tanks and the circuit for the fuel gauge.
Originally Posted by hbphc34
It looks like the wires to the valve come in and then back out to each pump.
Out wires just go to the fuel gauge senders in each tank.