First... make sure that the security system isn't tripped. If the security light is blinking it is tripped. It will kill the fuel circuits on purpose. If that's the case you need to have it reset. Your local ford shop should be able to do it. If not... start with the relay. Ford has never been able to nail down the proper way to make a fuel supply circuit. They've had relay/inertia switch problems since they started computertizing their vehicles. I can't begin to tell you how much I hate bronco II's and explorers their fuel pump relay troubles!!
Make sure you not only test the relay but the socket as well. sometimes the sockets wear out from vibration and don't make good contact. Use a test light and make sure you have power to the relay. if it's clicking that doesn't always mean it's good!! make sure that it's actually turning the power on and off to the fuel circuit. If you are getting power output... Use an ohm meter between the output side of the relay and the input side of the inertia switch.. You should have a reading of 0 - 0.05 ohms. If you have an open loop or more than 1 ohm you likely have break in the wire. Best way to find it is start by wiggling the harness while watching the meter. Sometimes you can narrow your search this way. But most likely if you have my kind of luck you will have to start untaping the harness and tugging on the power wire. You'll know when u have a bad spot because it will stretch and break with little resistance. And there will probably be green crap inside the insulation. cut out the bad section and spice in some new wire. Should fix u right up. Wiring issues can be a nightmare but just start in one place and start eliminating stuff. Eventually you'll find the problem. If all else fails and you have a couple circuit breakers available, make up two jumpers with an inline circuit breaker (so you don't accidently fry something). Jumper the inertia switch first, then the relay. The pump should spin up *assuming the pump is good* but you should at least get power to the fuel pump harness. If you don't. you've bypassed anything but wiring so the problem lies in the wires!! I work on fords every day and I can't begin to tell you how many I've had to spend HOURS ripping apart wiring harnesses to find a dumb corroded wire causing alllll the greif... Just break it down and eliminate one component at a time. eventually you'll find the problem! Just have patience..
HOPE THIS HELPS!
