I have a 1990 F150 with duel tanks. Neither fuel pump is working already changed relay. What else do I need to check before replacing pumps?
fuel pump on 1990 Ford F-150
There is a fuseable link in wiring harnest somewhere. There is also a frame fuel pump near your fuel filter and duel tank relay they are located under the driver side front floor pan. You may also lower each tank and remove the sending unit. Then grab a battery charger set it as you wanted to charge a battery over night the fuel are marked negative and positive on them. you can test them with out buying them by touching the battery charger leads to the wire leads on each of the three fuel pumps.
Check for voltage and ground at the connector for each pump when your are CRANKING the truck. You may have to lower each tank a little to gain access to the connector.
fuel slector switch