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if low pressure (carby) disconnect fuel line and observe flow. If high pressure (FI) connect fuel pressure guage and observe pressure. Check fuel filter while doing all this. Filters are the source of many problems that start people messing with fuel pumps.
First check the fuses... with a volt meter.. don't just look at them.. When you turn on the key the ign switch powers up the computer... .. The computer sends a single to a relay.. the relay comes on for 1.5 seconds when you turn the key to on to charge the system.. after you crank it for a few turns the fuel pump come on to keep the engine running. Turn the key to on and listen for that 1.5 sec. pump run.. if you have to go under the car and have somebody else turn the key.. if you hear it running then the fuel pump runs.. if you do not hear it run check that the ign switch is sending power to the acessories/computer. then check the relay to see if it is operating when you turn the key to on.. listen to it and touch it.. yyou should be able to hear it and feel it click. Just because the pump is running does not mean that it is pumping...so the next step is to hook up a pressure guage to the fuel rail and see if there is any pressure. (Harbor freight tools if you do not have one) You can jump the pump with a 12v wire.. jump it at the pump connector on top of the tank. if it runs check the fuel pressure.. if there is none.. or very little the pump is bad.. or the fuel filter is clogged.. or the pick-up filter in the tank attached to the pump is clogged.
check fuel pump fuse and relay also the fuel injection fuse and ecu fuse, if they are ok remove the back seat and you will see a cover remove the cover and check for voltage at the pump plug and ground, you hear the pump work if not need new pump
Get some engine starter spray. Follow instructions on spraying into intake. This will serve as a fuel source to test spark/ignition. You will want help cranking the car while you spray. If car stumbles and tries to run, you have a fuel problem. If after trying for a few minutes there is no change, then I would bet you don't have spark. Of course you could go further and say there could be a timing issue, no compression, etc. But I would start with the easy stuff first.
When was the last time you did a tune-up? Are the plugs in good shape?
Make sure the fuel pump is kicking on it won't hurt to check the relay but I have never seen one bad yet it could be the plug on the plug on the end of the wires that plugs on the pump this run hot and it burns the ends alot several fuel pumps are replaced because of this make sure you have power at the pump if you can't hear it run it will only stay powered for a few seconds and then kick off. so you might need someone to turn it on while someone checks the power.
It sure could be. But, first...by "won't turn over" you do mean it cranks at normal speed but won't start? A simple test of the fuel pump is to stand by tank and listen as someone turns key to on. When first turned to on, your pump will activate for 2 or 3 seconds, pressurizing the fuel system, and then shut off if the engine computer doesn't get a cranking signal. Do you hear it come on? If not, then something's not turning your pump on. If you can hear it buzz on briefly, then maybe it's your filter. Another test: Spray a little starting fluid into your intake manifold (remove the big hose going into intake manifold) while someone tries starting it.If it doesn't fire and try to stay running, then it's probably an ignition problem. But if it does fire off, then you know it's a fuel problem-likely your pump or filter. good luck.
what do you mean by "dash lights"? how do you KNOW the pump isnt working? how do you KNOW its good? at the ignition switch the ORANGE and PINK should have power in the RUN position the BROWN and TAN/WHITE should also be HOT in the run position. There should be a red wire near the fuel pump relay, make sure its HOT when cranking. IF its HOT and the fuel pump doenst run, the pump is bad. You can also put 12V on that red wire and power the pump.
do you mean the truck won`t start and run or do you mean it won`t turn over with the key.if it won`t turn over with the key the you may have a starter problem.if you mean won`t start then it could be the fuel pump not working.with someone cranking the motor you should hear the fuel pump running with the gas cap off and listening at the filler neck.or hear it running listening under the truck at the gas tank.if you don`t hear it then you can hit the tack sharply with your hand or a rubber hammer,it hear the pump start to run then the fuel pump needs replacing.if not check the fuses under the dash and under the hood.if they are good then it may be the pump relay in the relay box under the hood and it should be marked on the box or lid.
I would check the ground for the fuel pump relay that operates the switch side of the relay.
You should have 2 12v inputs to the relay. When the relay gets 12v input, it closes the relay switch on the heavy current side that sends 12v to the fuel pump.
A relay is needed because you don't want heavy current going through the switch.
Also, most cars only run the fuel pump for 2 seconds when the key is turned on because you don't want the fuel pump running without the car running. If you listen closely at the fuel tank, you should hear the pump run for 2 seconds when you turn the key to "ON"
When the key is turned to "START", the fuel pump should run continuously.
The engine computer tells the fuel pump to shut off if the engine rpms are zero.
So, I would check the switch side of the relay. Power amd ground.