1992 Ford F-250 Won't start

Someone is just guessing and you're replacing parts without diagnosing anything. As you can see, that gets real expensive, and it's not an effective way to troubleshoot a problem.

The fuel pump should only run for about one second after you turn on the ignition switch to insure fuel pressure is up for starting in case it bled down overnight. It should never run any longer on any brand of vehicle unless the engine is rotating, (cranking or running), because to continue running would pose a major fire hazard. If a fuel line gets ruptured in a crash, raw fuel would get dumped onto the ground. Instead, the engine can't run without fuel pressure so it stalls. That kills some sensor signals which tells the Engine Computer to turn the fuel pump off.

There's three things that will cause a fuel pump to run continuously. The first is a defective Engine Computer. I know the capacitors you're referring to because I find them in tvs, but you aren't going to solve a problem in an Engine Computer with those.

The second thing is a sticking fuel pump relay. You can unplug that to stop the fuel pump, but when you do, try to feel for the light click of it turning off. If you can detect that, more than likely the computer is keeping it turned on.

The third thing, which could also be related to the no-start condition, is a dirty signal coming from the distributor pickup coil. Unplug the distributor. If the fuel pump stops running, it's because the pickup coil or the TFI module is generating noise, in effect, static, and the computer is interpreting that as the signal is sees when the engine is rotating. Any signal, even when it's incorrect, can trick the computer into turning on the fuel pump relay.

I'd have to dig up a wiring diagram to see if your engine uses a crankshaft position sensor in addition to the distributor pickup. If it does, unplug that too. Three-wire sensors have electronic circuitry inside that can generate that noise. Two-wire sensors have only a magnet with wire wrapped around it. There have been cases where that magnet has cracked and poor signals get generated. Usually that won't make the computer turn the fuel pump on though, and it often causes popping and backfiring due to it generating multiple signals.