Andy Owens

Hello, my name is Andy, I have a 1995 ford f150 flat six truck, that seems to have a fuel pump issue, it was running fine, I recently replaced the computer, cleaned the injectors, new plugs, new plug wires and then I pulled into a store, left if running when I went inside, when I came out, put it in gear and it abruptly died. It would'nt start back, but after sitting a while it started, then died again, then did that again, then wouldn't start at all. it has dual tanks and it wont start on either tank. On a dual tank truck, are there dual fuel pumps also on the fuel tanks? It would seem that if the front fuel pump was bad, that it should start on the rear tank, but I tried that. Ideas?

madd

check the switch on the dash for corrosion,they screw up a lot. but first prime the fuel system and use a gauge on the fuel rail to see if the pressure reaches around 50psi. If it bleeds down real fast then something else is wrong. The dual tank system has many issues. So you need to diagnose first to see whats going on.

andretti05

Sounds to me like a possible electrical issue. If the truck won't start on either tank there is probably something wrong with the electrical feed to the pumps. Use starting fluid and see if it starts right up. This will eliminate no spark/ignition as a possible cause for your problem, then you can focus on the fuel system. If you confirm that the issue is fuel related, start checking the electrical system for the fuel pumps. Maybe something went wrong when you changed the computer, there could be a bad wire/connector somewhere, the selector switch could do it as well. If you can't find it, try getting a wiring schematic from a ford manual and test the circuit for any issues.

fosgate3

I have a 95 with a 302. There are dual pumps if you have dual tanks. When I turn the key, I can hear the fuel pump hum in the tank. You should be able to do the same. If it hums, then you know your pump is coming on and most likely working (in my experience, they either work or they dont). If it's humming, then I would check the output side of the filter and make sure you have fuel coming out. Both tanks will feed into the one filter. From there, it goes into the fuel rail on the engine. Before I get to that point, I look at checking the coil next and make sure it's giving an output to the plugs. No coil output = no spark = no run.

If you don't hear a hum at the tank, then check the electrical. Make sure that when you turn the key to the "on" position, it is sending voltage to the fuel pump relay under the hood. If I remember correctly, this either sends current directly to the pump OR to the inertia switch (mine is under the carpet on the passenger side of the truck, up high under the heater core) which then sends current to the fuel pump. It's really best to check voltage at the pump itself but that will require you to pull the tank. If voltage is good, then I would look at the pump being the problem. If you can swap tanks and the truck starts, then that will tell you immediately that the pump in one tank is bad. If you swap tanks and it still doesn't start, it's possible that both pumps went out simultaneously but the odds of that happening increase.

fosgate3

And the suggestions from madd and andretti are both good too. If the fuel tank selector switch is unplugged, you will not be able to start the truck. Likewise, if the switch is corroded to the point that proper contact cannot be made, then current will not flow and you probably won't be able to start the truck. My F150 has 340k miles on it and I haven't had a problem with my switch, fuel rail, or injectors. I had to change the pump in the front tank and filters, plugs, wires, and dist as needed. And with the coil, it either works or it doesn't. And when was the last time you change the distributor? If the contacts in it are corroded, you won't get fire.

And all this is assuming the truck is turning over and trying to start. If it won't even try to turn over, then you either have a battery, starter relay, starter solenoid, or a starter motor problem, or a problem with the wire going from the key to the top of the start relay. When you turn it over to start, it sends voltage to the top of the starter relay located on the firewall which then sends voltage to the starter, throwing the bendix out and turning the flywheel to start the vehicle.