I have a 2001 Jeep Grand Cherokee Laredo with an inline 6. The original fuel pump started whining, so I replaced it with an inexpensive version. It started whining shortly thereafter. I send it back and got a Bosch fuel pump. It started whining a few weeks after. I have lived with it for six months, and just recently replaced the fuel filter. It did not whine for a day. It also whines intermittingly. I have no idea what it could be. Any help would be appreciated.

 

Welcome, cat!


I'd say you need to check three things:

1. Cleanliness of the tank. If there is a bunch of grunge in there, it will kill pumps.
2. Power supply line to the pump. I don't mean just checking with a voltmeter to see if it has power, but check the resistance between the power supply at the pump (yeah, might have to drop the tank to get to it) and the battery positive terminal. Do this while disconnected from the battery. Don't just do a continuity check, measure the actual resistance (ohms). The reason for this is that you can get voltage which will measure correctly at the pump, but if there is corrosion on the path, once you turn on the pump, the voltage drops and this can kill the pump.
3. Check the ground to the pump. Same idea as #2.