1996 chevy k1500 w/350 eng.fuel system

Black is ground, gray is power to the pump.

The problem on your vehicle is much more likely to be the oil pressure sending unit ore the fuel pump relay . The way the systems works is the fuel pump is supplyed by the fuse box fuse #9 but the cirrcuit splits and goes to the oil pressure sending unit in case the relay fails when your drivering the fuel pump will still have a power supply its stupid but its a safty thing that was mandated. If the fuel relay is NG the vehicle will still start but it takes the engine some time to build up enough oil pressure to trip the switch inside the sending unit to send volatge to the starter . Witch means slow starts long cranking times I would check the fuel filter first but realsticly if you don't know if the fuel pump has been replaced or you haven't done it your self this is vary likely the cause of the problem . If you have then try the oil pressure unit

It sounds like the oil pressure sending unit . The way a lot of chevy engines work is the oil pressure sending unit is a back up power supply for the fuel pump . So evern if the fuel pump relay is bad the pump will still get power through the oil pressure sending unit its a split curicut .However it will make a longer cranking time until the oil pressure can reach enough pressure to trip the sending unit to send the voltage to the fuel pump . If you have a 4.3 the sending unit is is in the extereme rear of the engine to the left of the disturbitur shaft and you need a speical deep socket to remove and install it . The part is about 20 dollars make sure you buy a good one and the tool is about the same

On some chevys the oil pressure sending unit closes the circuit to continue the fuel pump to run after start. In the event of a wreck ,the car stops running thus no oil pressure thus turns off power to the fuel pump .A safety to help prevent fires. When you first start the car, the computer turns on the fuel pump for about 20 seconds just enough time to start and allow the oil pressure sending unit to close the circuit to allow it to continue running. when the car car has NO oil pressure or the sending unit fails ,it will start then shut down..as many times as you try to start. replace the oil pressure sending unit and secure a good conection. Dan

Check your fuel pump relay Alot of chevy systems back up the fuel pump power supply through the oil pressure sending unit . So even if the relay is NG the vehicle will still start and run because the oil pressure sending unit is feeding the pump . It also could be a combination of bolth a bad relay and the O P sending unit it needs to build up enough engine pressure to trip the switch inside the sender to send voltage to the fuel pump and it would do this much better if it was cold the oil is thicker

the fuel pump is in the gas tank and the fule filter runs along the bottom of the Driver side..if your looking at the gas tank follow the gas lines that go toward Eng. you will see the Fuel filter

u need to have the codes ran on it but if u havent changed the fuel filter its prolly stopped up, and that usually wipes out the fuel pump.

Fig. Fig. 1: Electric fuel pump-TBI engines

1. With the engine turned OFF , relieve the fuel pressure at the pressure regulator. Refer to the fuel relief procedure in this section.
2. Disconnect the negative battery cable.
3. Raise and support the rear of the vehicle on jackstands.
4. Drain the fuel tank, then remove it.
5. Using a hammer and a drift punch, drive the fuel lever sending device and pump assembly locking ring (located on top of the fuel tank) counterclockwise. Lift the assembly from the tank and remove the pump from the fuel lever sending device.
6. Pull the pump up into the attaching hose while pulling it outward away from the bottom support. Be careful not to damage the rubber insulator and strainer during removal. After the pump assembly is clear of the bottom support, pull it out of the rubber connector.

1. Connect the fuel pump to the hose.

Be careful that you don't fold or twist the strainer when installing the sending unit, or you'll restrict fuel flow.

1. Install a new O-ring on the pump assembly and then position them into the fuel tank.
2. Turn the locking ring clockwise until its tight.
3. Install the fuel tank and connect the battery cable.

If you dont feel like dropping the tank and hassling with the hangers because they often break cut a hole in the bed of your truck over the tank where the fuel pump is but be careful not to hit the wires. dont cut the piece out completely cut it so you can pry it up to oneside

find and replace your fule pressure regulator. a repair manual will make this possible for you. also check that book for other trobleshooting solutions for it cranks but wont start. good luck.

On the driverside of the engine towards the back of the intake your fuel lines run there. you will see a black cap that covers the fuel pressure test port. you will need to get a pressure tester if you do not have one. it will screw onto the fitting there. your pressure should be 40 to 60 psi. as for the fuel pump it is located in the fuel tank. it is the fuel module. it contains the fuel pump and sending unit. I hope this helps.
Reno