If you own a chevy truck, it may be necessary to jump the fuel pump relay. But how to jump the fuel pump relay on a chevy truck? To do this, you’ll need jumper cables, a multimeter, and a voltmeter.
Attach the jumper cables to the two wires on the fuel pump relay. Use a voltmeter to check for a voltage reading that matches what the multimeter shows. If the voltage is low, replace the fuel pump relay and try starting the vehicle again.
Check for constant voltage on pin 30
To determine if the resistor is out of spec, you should check the constant voltage on pin 30 of the fuel pump relay. Simply disconnect the oil sender wire and then test the wire by turning on the key “RUN.”
If you get a constant voltage of 5.94 volts, the fuel pump resistor is out of spec and needs to be replaced.
Secondly, check to see if the relay is in good shape. When the ignition is on, the fuel pump relay should have a constant voltage on pin 30. If the resistor is blown, replace the fuel pump or the harness.
If both of these steps fail, the fuel pump itself may need to be replaced. The easiest way to test it is to open the engine compartment and turn on the truck.
Check for constant voltage on pin 30 with the ignition on
The problem is most likely with the fuel pump relay. You may want to check the wiring in order to pinpoint the location of the fuel pump relay. Check for a constant voltage on pin 30 with the ignition on and the truck running. If this voltage is constant, the fuel pump is working. Jumping pin 30 and 87 to the fuel pump relay may help you troubleshoot this problem.
To test the relay, simply connect a jumper wire from the positive terminal of the battery to the other terminal. The other terminal is connected to ground. After the second connection, the jumper should click. If you see no click, the relay is likely bad and if this does not help, try replacing the relay. If it does not click, you may have to replace the relay.
Check for constant voltage on “S” terminal
If you see a constant voltage on the “S” terminal of the fuel pump relay, you have to check the resistor. The stock resistor is a ceramic power resistor with the rate at 1.4 Ohms, or 10 Watts.
This type of resistor wears out over time, and may even be out of spec if the vehicle is hot. When heated, the resistor will increase in resistance and choking off voltage to the fuel pump.
If you notice a constant voltage on the “S” terminal of the fuel pump relay, you may have a problem with the relay. You can fix this by replacing the fuel pump. Check the wire from the factory, pin 87.
The wire should run to the fuel pump. If it is connected to a different wire, it could be a different problem altogether. If the “S” terminal is plugged in incorrectly, it can cause a faulty pump.
Check for constant voltage on “S” terminal with the ignition on
Ensure that the battery properly connects by examining the resistance of the ohmic values. They should be between 10 and 15 ohms. You can find the necessary information in different service manuals.
In case you don’t have one, you can refer to the Internet for help. In some cases, a faulty ignition power stage can cause the engine to cut out at speed.
If you can’t see this voltage, the problem may lie somewhere else. Regardless of whether the problem is in the relay or in the ignition switch, you can easily check by locating the connector for the fuel pump.
The connector is located anywhere on the wiring diagram (left side of page), on the PCM, or on the ignition switch. Another cause may be a loose relay socket terminal. Sometimes, the socket terminal will widen to grasp the male relay terminal.