90' F150 4.9 I-6. How can i tell if my fuel pump is bad? Other than raising the bed , or yanking down the tank , what can i do?
Turn on the key and go to the rear of the vehicle. you should hear it humming. failing that just remove the gas cap and listen.
robert
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Perform a presure test at the engine,but there are two pumps on this models,one low pressyre pump in the tank and a high pressure one mounted on the vehicle frame that is the one that go bad more often,so its not a pain to replace, also you can perform a volume test(this one all you need to do is unhook the line to the fuel rail and place the line in a container,at idle it should pump about a pint in 20 seconds.for the pressure test you need a presure gauge the pressure should be between 40 to 50 pounds and hold it for about 10 min.
Ya there are a few simple things , just listen for the hum of the fuel pump when you first turn the key to the position just before start, this is a large vehicle so have an assistant listen down toward the back wherte the gas tank is the hum should be present for about 3 - 5 seconds the shut off if this sound si present the fuel pump is activating and building up pressure in the fuel line, the next step is to check the fuel pressure with a high pressure fuel pressure tester at the fuel rail located on top of the motor, there is a access valve with a black cap where you can check fuel pressure, however the price of the tester is about $60.00 also make sure the vacuum line at the fuel pressure regulator located at the end of the fuel rail is not broken or cracked in any way.
Got 2 89 F 250's. both had same problem. after buying the book and reaing thru it I found there is a way to GROUND one of the wires in the DLC connector on drivers fender well. With a van Idk if it will be located in the same spot, however, with both trucks it allowed me to immediately tell the pump was working just fine and in both cases was a fault in the fuel pump relay plug that was hidden. FWiw
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