How to Replace the Fuel Pump On a Jeep Cherokee

While on an off road trip, Jenny's Jeep began to perceive the symptoms of a bad fuel pump. Her jeep would stumble and die at idle. It would only run if the rpms were kept over 1500 and it was low on power. It was also surging as the fuel pump lost pressure. It was production only 20 psi or so and that was naturally not sufficient to keep the fuel from boiling in the hot fuel rail. It was a struggle, but we got her Jeep out of the woods under its own power and got it back to my shop.

Fist, we used the failing fuel pump to pump the remainder of the fuel from the tank. I used my fuel pressure tester attached to the fuel rail test port to pump the fuel into a can. I made a jumper wire and attached it to the fuel pump relay socket to force the pump to run.

3000 Psi

Once the tank was empty, I disconnected the lines from the fuel pump assembly and disconnected the wires. I also disconnected the tank vent lines.

Next, I rigged up a lift to maintain the tank as I lowered it from the Jeep. I then loosened the tank maintain straps. After lowering the tank a consolidate of inches I was able to reach above the tank and loosen the filler and vent lines from the tank. I then removed the tank maintain straps and lowered the tank out of the Jeep.

With the tank out, I stood it up and cleaned the mounting flange for the pump assembly with a wire brush. I used a hammer and screwdriver to move the clamp ring off the pump. Then I thought about removed the pump from the tank taking care not to get dirt in the tank. The filter sock fell off and had to be retrieved with a gripper tool. Often the tapered grommet for the pump assembly will stay in the tank as well. If so, this has to be fished out. This one came out with the pump this time however.

To test the pump, Jenny made up a container for fuel and reconnected the pump to the lines and wires. The last time I worked on this Jeep there was a leak in the line between the pump and the tank outlet. This time however, there was no leak; the pump naturally was not production pressure. Cold it would make only 30 psi not the required 48 psi. When the pump got hot it made less pressure. We measured 20 psi when the Jeep was trying to get home the day before.

We then tested the used transfer we had available. It positively made more than sufficient pressure. And still no leaks. The mounting bracket in this tank has been modified slightly in an off roading mishap so I had to adapt the new pump to fit. After some mixing and matching of parts and some creative routing of the high-priced high pressure hose, I got it to fit. Jenny also had to put a wrap or two of Teflon tape on the pump inlet to get the filter sock to stay in place.

I thought about cleaned the pump mounting surface and the O ring. I then set the pump in place and tapped the retaining ring back into position.

We then lifted the tank up into the Jeep. With the tank practically in place I reattached the filler and vent lines. This was the most difficult part of the job by far. Once the lines were reattached, I lifted the tank the rest of the way back up and reinstalled the straps. I positively forgot to tighten the fuel line clamps before driving it. I should have tightened them right after I reinstalled the lines and attached the wires.

We put the fuel back in and ran the pump on the jumper a occasion to prime the theory and get air out of the lines. When I heard the regulator squeal, I knew the air was being purged. Jenny's Jeep started right up. It stumbled a occasion while the computer adapted to having the right pressure at the injectors again but it placed down quickly.

A quick test drive showed it all worked fine. With the irregularity of the loose clamps on the fuel lines I mentioned earlier. I had to tighten them in the street because I was afraid they might pop off if we drove it back to the shop. Her fuel pressure is back in spec again. Hopefully this pump will last a while. The whole job took about four hours start to finish.

How to Replace the Fuel Pump On a Jeep Cherokee

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