Replacing The Fuel Pump In A 1999 Mercury Mountaineer

If you're experiencing issues with your 1999 Mercury Mountaineer, you may need to replace the fuel pump. The fuel pump is responsible for delivering pressurised gasoline to the fuel injectors in the car's engine. While a high-quality fuel pump can last a long time, it will eventually degrade and need to be replaced. You can attempt to replace the fuel pump yourself, but given the risk of fire, it's recommended to get it replaced at a repair shop by a qualified mechanic. The cost of replacing a fuel pump can vary depending on your location, but on average, it will cost around $675, with $248 for parts and $427 for labour.

Disconnect the negative battery cable

Disconnecting the negative battery cable is one of the first steps to take when replacing the fuel pump on a 1999 Mercury Mountaineer. Here is a detailed, step-by-step guide on how to do this:

Before beginning any work on your vehicle, it is important to ensure your safety. Put on a pair of safety glasses to protect your eyes from any debris or sparks.

Locate the negative battery cable. This should be clearly visible on the battery, as it will be marked with a minus (-) symbol. The cable will be clamped to the battery terminal.

Once you have located the negative battery cable, it's time to disconnect it. Using a battery terminal wrench, loosen the clamp that secures the cable to the battery terminal. Be sure to set the wrench to the correct size for the clamp. You may need to apply some force to loosen the clamp, but be careful not to strip the threads on the clamp or damage the battery terminal.

After the clamp is loosened, carefully remove the cable from the battery terminal. Ensure that the cable does not touch any metal parts of the vehicle, as this could cause a short circuit.

Now that the negative battery cable is disconnected, you can proceed with the next steps of replacing the fuel pump. It is important to work safely and methodically when performing any automotive repairs. If you are unsure about any steps or procedures, consult a qualified mechanic or seek advice from a trusted source.

Remember to reconnect the negative battery cable once you have completed the fuel pump replacement and before starting the vehicle. Tighten the clamp securely to prevent any issues with power supply or electrical connections.

Jack up the rear of the Mercury

Jacking up the rear of the Mercury is a crucial step in replacing the fuel pump on a 1999 Mercury Mountaineer. Here is a detailed, step-by-step guide on how to safely and effectively jack up the rear of the vehicle:

Park and Prepare the Vehicle:

Before beginning any work, ensure the Mercury is parked on a flat, level surface, and engage the parking brake. Chock the front and rear of the driver's side front tire for added safety. It is also recommended to wear safety gear, such as safety glasses, to protect your eyes.

Position the Jack:

Place a jack at the rear of the Mercury, positioning it under the center of the fuel tank. Use a one-foot length of 2x4 as a buffer between the jack head and the bottom of the fuel tank to avoid damage.

Lift the Vehicle:

Using the jack, carefully lift the rear of the Mercury to a height that allows you to comfortably work underneath. Ensure the jack is stable and securely positioned.

Secure the Vehicle:

Once the vehicle is at the desired height, place jack stands under the rear to support the weight. Carefully lower the jack until the vehicle is resting securely on the jack stands. Ensure the jack stands are positioned in a way that does not interfere with the fuel tank lowering process.

Remove Fuel Tank Straps:

Using a socket set, remove the bolts holding the fuel tank straps in place. Have an assistant nearby to help support the fuel tank and guide its movement as needed.

At this point, you have successfully jacked up the rear of the Mercury and can proceed with the next steps of the fuel pump replacement process, such as disconnecting the wiring harness and fuel vapor return lines. Remember to work cautiously and refer to a repair manual for additional guidance if needed.

Remove bolts holding the fuel tank straps

To remove the bolts holding the fuel tank straps, you will need a socket set.

First, put on your safety glasses and jack up the rear of the Mercury. Set it down on the jack stands, positioning the jack stands so that they will not interfere with lowering the fuel tank. Raise the jack back up 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.

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 at this point so that it does not move on its own.

Disconnect the wiring harness and fuel vapour return lines

Disconnecting the wiring harness and fuel vapour return lines is a crucial step in replacing the fuel pump of a 1999 Mercury Mountaineer. Here is a detailed, step-by-step guide on how to safely and effectively complete this task:

Step 1: Prepare the Vehicle

Before beginning any work, ensure you have the necessary tools and safety equipment, including safety glasses and a battery terminal wrench. Drive the Mercury until the fuel tank is almost empty, and park it in a safe, well-ventilated area. Pull the fuel pump relay, located in the relay box under the hood, while the engine is running, causing it to stall out. Remember to set the parking brake.

Step 2: Access the Fuel Tank

Disconnect the negative battery cable using the battery terminal wrench. For safety, place wheel chocks at the front and rear of the driver's side front tire. Jack up the rear of the vehicle and secure it on jack stands, ensuring they don't interfere with lowering the fuel tank. Use a socket set to remove the bolts holding the fuel tank straps. You may need an assistant to hold the tank at this point.

Step 3: Disconnect the Wiring Harness and Fuel Vapour Return Lines

Lower the jack a few inches so you can reach the fuel pump connections. Disconnect the wiring harness and the fuel vapour return lines from the fuel pump assembly. Gently lower the fuel tank further to access and disconnect the filler neck, typically held by a bolt in a retaining strap.

Step 4: Remove the Fuel Tank

After disconnecting the necessary lines, carefully pull the fuel tank out from under the vehicle and place it on the ground. Wrap a rag around a flathead screwdriver and use it, along with a mallet, to carefully turn the retaining ring holding the fuel pump in place. Lift the old fuel pump out of the tank and set it aside.

Step 5: Install the New Fuel Pump

Install the new fuel pump, being cautious not to pinch the new gasket when reseating the retaining ring. Before moving on, ensure that the new pump is securely in place.

This process requires attention to detail and a methodical approach to ensure safety and avoid damage to the vehicle. Always refer to a repair manual for specific instructions and take appropriate safety precautions when working with fuel systems.

Remove the fuel tank and set aside

To remove the fuel tank and set it aside, follow these steps:

First, drive 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 the 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 your safety glasses and jack up the rear of the Mercury. Set it on jack stands, positioned so they won't interfere with lowering the fuel tank.

Raise the jack 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 tank at this point.

Lower the jack a few inches so you can reach the wiring harness and fuel vapour return lines. Disconnect them, then lower the tank further and disconnect the filler neck (held on by one bolt in a retaining strap). Pull the fuel tank out and set it carefully on the ground.

Now you can remove the fuel pump from the tank. 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 tank and set it aside somewhere safe.

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