Where are the relays on a fuel pump?
That inside fuse box is also where you’ll find two fuel pump relays. Both must turn on for the pump to run. Relay number 1 turns on when the ignition switch is turned on. Relay number 2 is turned on by the Engine Computer for that first one second, then again during engine rotation, (cranking or running).
What causes a fuel pump to stop working?
However, this can happen due to several other reasons, such as a choked fuel filter, so you should always properly diagnose your car before replacing any parts. If the fuel pump relay may have any bad solderings inside it, it might suddenly lose the relay connection and stop delivering power to the fuel pump.
How to test a GM 4.3L fuel pump?
More GM 4.3L, 5.0L, and 5.7L Tutorials. It’s very important that you start off your fuel pump relay diagnostic by first testing the fuel pump pressure with a fuel pressure test gauge. If the fuel pump relay IS NOT activating the fuel pump, the fuel pressure test gauge will register 0 PSI when cranking the engine.
What are the symptoms of a bad fuel relay?
Here is a more detailed list of the most common symptoms of a bad fuel relay. The engine control module does always monitor all engine sensors to ensure they do not show the wrong values. If the ECU suspect a wrong value from any sensor, it will light up the check engine light.
That inside fuse box is also where you’ll find two fuel pump relays. Both must turn on for the pump to run. Relay number 1 turns on when the ignition switch is turned on. Relay number 2 is turned on by the Engine Computer for that first one second, then again during engine rotation, (cranking or running).
Where is the fuse for the fuel pump?
If you never hear the hum of the fuel pump, either during cranking or for that first one second after turning on the ignition switch, look first for fuse number 10, a 15-amp, in the under-hood fuse box, then fuse number 8, a 7.5-amp fuse in the inside fuse box on the left end of the dash.
What causes a fuel pump to not start?
Defective fuel pump circuits cause the crank/no-start problem only about five percent of the time. A loss of fuel pump and spark causes closer to 95 percent of these failures, but most people get stuck on the first thing they find missing and forget to look for other things that are dead.
Where are the 12 volts on the fuel pump?
The most common mistake is expecting to find 12 volts at the fuel pump when just turning on the ignition switch. The first thing to do is try to listen for the hum of the pump for just one second when you turn on the ignition switch. Sometimes that is hard to do with the chime making noise.