How to Change the Fuel Pump on a Mercury Mountaineer

by Allen MooreUpdated November 07, 2017
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Items you will need

  • Battery terminal wrench

  • 2 wheel chocks

  • Safety glasses

  • Jack

  • 2 heavy duty jack stands

  • One-foot length of 2x4

  • Socket set

  • Rags

  • Flathead screwdriver

  • Rubber mallet

  • Replacement fuel pump

  • Haynes Manual specific to your Mercury

First introduced in 1997, the Mercury Mountaineer is the high-end cousin of the Ford Explorer, one of the most popular American-made SUVs on the road. The Mercury differs in interior styling and some minor outward enhancements, but mechanically it is essentially the same vehicle. Replacing your fuel filter every 15,000 miles will go a long way to ensuring a solid life for your fuel pump. If you own your Mercury long enough, you are bound to be faced with replacing the fuel pump sooner or later.

Drive the Mercury until you are just about out of gas. Park it where you will perform the work and pull the fuel pump relay (located in the relay box under the hood) while the engine is running. The engine will stall out after a few seconds, once it has lost fuel pressure. Set the parking brake before getting out.

Use the battery terminal wrench to disconnect the negative battery cable.

Place the wheels chocks at the front and rear of the driver's side front tire.

Put your safety glasses on and jack up the rear of the Mercury. Set it down on the jack stands. You should position the jack stands in such a way that they will not interfere with lowering the fuel tank.

Raise the jack back up and position it under the center of the fuel tank, using the 2x4 as a buffer between the jack head and bottom of the tank.

Use the socket set to remove the bolts holding on the fuel tank straps. At this point, you may want to have a helper hold onto the fuel tank so it does not move on its own.

Lower the jack a few inches until you can reach up and disconnect the wiring harness going to the fuel pump and the fuel vapor return lines. Once that is disconnected, jockey the fuel tank down farther until you can disconnect the filler neck, which should be held on by one bolt in a retaining strap.

Pull the fuel tank out from under the Mercury and set it carefully on the ground.

Wrap a rag around the tip of a flathead screwdriver; place the tip of the screwdriver against the retaining ring holding the fuel pump in place and carefully tap the screwdriver with a mallet to turn the ring until the fuel pump is free.

Lift the fuel pump up and out of the fuel tank and set it aside somewhere safe.

Install the new pump, being careful not to pinch the new gasket as you re-seat the retaining ring.

Move the tank back into place far enough so that you can reconnect the fuel filler neck. Then, lift the tank up farther so you can reconnect the wiring harness and the fuel vapor return lines to the pump assembly.

Lift the fuel tank back into position and bolt the retaining straps back in place.

Plug the fuel pump relay back in, reconnect the negative battery cable and turn the key to the run position and listen for the pump to cycle. Do this four more times before starting the Mercury. Once it is running, carefully inspect for any fuel leaks around the tank.

Lower the Mercury back to the ground.


It is always best to replace the fuel filter when you replace the pump. Whenever you perform repairs to your vehicle, it is best to keep a repair manual handy for quick reference. The Haynes Manuals are created by a group of mechanics who completely disassemble and reassemble a vehicle, detailing every step of the way. For anyone who is not a factory-trained technician, the Haynes Manuals are easir to understand and follow than the factory repair manuals.


Never work on a fuel system near open flames or while smoking.

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