Replacing Fuel Pump In '99 Mercury Mountaineer: How Long Does It Take?

The Mercury Mountaineer, first introduced in 1997, is the high-end cousin of the Ford Explorer. While the Mercury differs in interior styling and some minor outward enhancements, it is mechanically the same vehicle. This guide will cover how long it takes to change the fuel pump on a 1999 Mercury Mountaineer.

Disconnecting the negative battery cable

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Before starting, gather the necessary tools, including a battery terminal wrench. This wrench is specifically designed to loosen and tighten battery terminals and is an essential tool for any automotive maintenance involving the battery. It provides the necessary leverage and grip to safely disconnect the battery cables.

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Locate the negative battery cable. The negative terminal is usually black and marked with a "-" symbol. It is often on the left side of the battery, but this may vary depending on your vehicle's make and model. Once located, proceed to the next step.

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Using the battery terminal wrench, loosen the nut that secures the negative battery cable to the terminal. Turn the wrench in a counter-clockwise direction to loosen it. Be careful not to strip the threads of the nut by applying too much force. You may need to break loose any corrosion that has built up on the terminal first. A wire brush can help clean the terminal if needed.

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After the nut is loosened, carefully remove the cable from the terminal. Ensure that you do not let the cable fall back onto the terminal, as this can cause a short circuit. You may want to use a piece of tape or a cable tie to secure the cable away from the battery. Additionally, it is good practice to cover the terminal with a piece of tape or a protective cap to prevent accidental contact.

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With the negative battery cable disconnected, you can now safely proceed with the fuel pump replacement. Remember to keep the work area well-ventilated and free of any open flames or sparks, as you will be working with flammable liquids and gases. Always refer to the vehicle's repair manual for specific instructions and safety precautions.

Jacking up the rear of the Mercury

Preparation:

Before you begin, it is essential to gather the necessary tools and safety equipment. Ensure you have a jack, jack handle, lug nut wrench, safety glasses, and heavy-duty jack stands. These tools are typically included in a standard Mercury jack kit, which can be located in your vehicle. Additionally, refer to your owner's manual to identify the specific jacking points and safety precautions for your model.

Pre-Jack Steps:

Prior to positioning the jack, there are several important tasks to complete:

• Chock the wheels: Place wheel chocks at the front and rear of the driver's side front tire. This will prevent the vehicle from rolling during the jacking process.
• Disconnect the battery: Use a battery terminal wrench to disconnect the negative battery cable. This step is crucial for safety, as it reduces the risk of electrical hazards.

Jacking the Vehicle:

Now you are ready to jack up the rear of the Mercury:

• Position the jack: Assemble the jack handle and carefully position the jack under the jack points. Refer to your owner's manual or a repair manual, such as the Haynes Manual, for the specific jacking points of your vehicle.
• Raise the vehicle: Use the jack to safely raise the rear of the Mercury. Ensure that you are wearing your safety glasses during this step.
• Secure the vehicle on jack stands: Once the vehicle is raised, carefully lower it onto the jack stands. Position the jack stands in a way that does not interfere with lowering the fuel tank. Remember, never get under the vehicle without properly supporting it with jack stands.

Additional Tips:

• Be mindful of your environment: Ensure that you are working in a safe area, as a passing vehicle could potentially hit and knock over your raised car.
• Avoid working alone: Consider having an assistant to help you during the process, especially when handling the fuel tank.
• Maintain proper safety measures: Working on a fuel system carries inherent risks. Avoid open flames or smoking near the vehicle, and always be cautious when working with flammable liquids.

By following these steps and staying cautious, you can effectively and safely jack up the rear of your 1999 Mercury Mountaineer, allowing you to access and replace the fuel pump.

Removing fuel tank bolts

To remove the fuel tank bolts of a 1999 Mercury Mountaineer, you will need a socket set. Before you begin, ensure you have driven the Mercury until you are almost 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 a battery terminal wrench to disconnect the negative battery cable. Place wheel chocks at the front and rear of the driver's side front tire. Put on safety glasses and jack up the rear of the Mercury. Set it down on jack stands, positioned so 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 a 2x4 piece of wood as a buffer between the jack head and the bottom of the tank.

Now, use the socket set to remove the bolts holding the fuel tank straps. You may want to have an assistant hold the fuel tank so it does not move.

Once the bolts are removed, carefully lower the jack a few inches until you can reach up and disconnect the wiring harness going to the fuel pump and the fuel vapour return lines.

Disconnecting the wiring harness

Step 1: Prepare the Vehicle

Before beginning any work, ensure you have parked your Mercury Mountaineer on a level surface and engaged the parking brake. For safety, it is recommended to wear protective gear, such as safety glasses.

Step 2: Access the Fuel Pump

Place jack stands at the rear of the vehicle, positioning them so they won't interfere with lowering the fuel tank. Use a jack to raise the rear of the vehicle and securely support it on the jack stands.

Step 3: Lower the Fuel Tank

Using a socket set, remove the bolts holding the fuel tank straps. You may need an assistant to help support the fuel tank as you loosen the bolts. Now, carefully lower the jack a few inches until you can access the fuel pump and fuel vapor return lines.

Step 4: Disconnect the Wiring Harness

Reach up and carefully disconnect the wiring harness that is connected to the fuel pump. This step may require some maneuvering, as you will also need to disconnect the fuel vapor return lines. Be cautious of any sharp edges that could damage the wiring harness.

Step 5: Lower the Fuel Tank Further

With the wiring harness disconnected, continue to lower the jack until you can access and disconnect the filler neck, which is typically held on by a single bolt in a retaining strap.

Step 6: Remove the Fuel Tank

Carefully pull the fuel tank out from under the vehicle and place it on the ground. Ensure you do not damage any nearby components or spill any fuel during this process.

By following these steps, you will have successfully disconnected the wiring harness of the fuel pump on your 1999 Mercury Mountaineer. Remember to exercise caution and refer to a repair manual if you need further clarification on any steps.

Removing the fuel tank

Before you begin, drive the Mercury until you are almost out of gas. Park it where you will be performing 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.

Wear safety glasses and use a battery terminal wrench to disconnect the negative battery cable. Place wheel chocks at the front and rear of the driver's side front tire.

Jack up the rear of the Mercury and set it on jack stands. Position the jack stands so that you can lower the fuel tank. Raise the jack again and position it under the centre of the fuel tank, using a 2x4 as a buffer between the jack head and the bottom of the tank.

Use a socket set to remove the bolts holding the fuel tank straps. You may want an assistant to hold the fuel tank at this point.

Lower the jack a few inches so that you can reach the wiring harness and fuel vapour return lines. Disconnect them, then lower the tank further until you can disconnect the filler neck, which is held on by one bolt in a retaining strap.

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

Now you can access the fuel pump. Wrap a rag around the tip of a flathead screwdriver and place it against the retaining ring holding the fuel pump in place. Carefully tap the screwdriver with a mallet to turn the ring until the fuel pump is free. Lift the fuel pump out of the fuel tank and set it aside.

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