I have a 1992 4.0 Cherokee Laredo. I purchased it 5 weeks ago and the fuel pump was loud so I replaced it and after 250 miles the new pump failed. I purchased a new fuel pump assembly and cleaned the gas tank. Changed the fuel filter, fuel pressure regulator. and fuel pump relay. After driving for 2 miles the fuel pump became very loud and the engine started hesitating. I would press the pedal and it had no power. Like there was no fuel. I thought I had bought a sorry pump(airtech) so I bought a used original pump. Jeep no longer makes a pump. I installed the used pump and I have the exact problem happening again. After I turn the engine off and it sits for a while it runs good for another mile and then the pump gets real loud again and the egine starts to run rough again. The pump is pumping and I do have good pressure on the return line. I do have a check engine light on, but it was on when I bought it 5 weeks ago. What is the problem? Please help. Thanks.

 

cycle the ignition key on and off on off and then on count flashes of chec ingine light see what the code is getting a manual will also help