Replacing Fuel Pump In '03 Bonneville: Step-By-Step Guide

Replacing the fuel pump on a 2003 Pontiac Bonneville is a complex task that requires mechanical expertise and a range of tools. It involves jacking up the car, removing the gas tank, disconnecting electrical plugs, and carefully handling fuel lines and hoses. The process also requires knowledge of fuel system components such as the fuel regulator, pressure sensor, and strainer. While some people choose to attempt this repair themselves, it is important to prioritise safety and accuracy to avoid potential dangers and further damage to the vehicle.

How to relieve fuel pressure before removing the pump

To relieve fuel pressure before removing the pump of your 2003 Bonneville, follow these steps:

Firstly, locate the fuel rail. This can be found under the bonnet, usually on the fuel rail near the intake manifold. Consult your car’s manual for the exact location. Once located, remove the fuel pressure relief valve cap. You can then attach a suitable pressure gauge to the valve and follow the manufacturer's instructions to release the fuel pressure.

Alternatively, you can relieve fuel pressure by removing the fuel pump fuse and trying to start the car. This will cause the car to starve itself of fuel, releasing the pressure.

Another method is to remove the gas cap, which will relieve the pressure, although this is disputed by some mechanics.

A further option is to pull the green fuel pump plugs apart and start the car to starve the engine of fuel.

Always ensure you take the necessary safety precautions when working with fuel and refer to your car's manual for specific instructions.

Location of the fuel pump relay

The fuel pump relay for a 2003 Bonneville is located in the Relay Center, which is behind the right-hand side of the instrument panel, above the shroud. The fuel pump relay is labelled 'N' in the diagram.

To check if the fuel pump relay is working, listen for a click when the key is turned on. The relay should click on when the key is turned and then click off 2 seconds later. If the relay clicks, try swapping it with one of the other relays in the panel.

If the relay is not working, you will need to check the fuse. The fuel pump fuse is located in the same panel as the relay, at location fuse #6.

Removing the gas tank

The first step in accessing and replacing the fuel pump on your 2003 Pontiac Bonneville is to remove the gas tank. This is a delicate process and must be done with care and attention to avoid any potential safety hazards.

Begin by parking the car on a level surface and engaging the parking brake. Remove any items from the trunk that may obstruct your access to the tank, and place old towels or cardboard beneath the tank to catch any spilled fuel. It is important to work in a well-ventilated area and to avoid any open flames or sparks.

Next, you will need to disconnect the fuel filler neck, which is located at the rear of the vehicle, behind the license plate. Carefully pry off the fuel filler door using a flat-head screwdriver, and then unscrew the fuel filler cap. Using a suitable wrench, disconnect the fuel filler neck hose by loosening the clamp that secures it. Be prepared to catch any spilled fuel with a suitable container.

Now, you will need to disconnect the electrical connections to the fuel pump. Locate the access panel inside the trunk, which is typically held in place by a few screws or fasteners. Remove this panel to reveal the electrical connections and fuel lines that run to the fuel pump. Carefully disconnect the electrical connectors, ensuring that you have support for the wires to avoid placing strain on the connections within the tank.

Finally, you can begin to lower the gas tank. Place a jack beneath the tank to support it, and slowly lower it down, ensuring that you have a clear path and no obstructions. Once the tank is lowered, you will be able to access the fuel pump for replacement. Remember to seal and secure all connections and hoses when reassembling, and always refer to a qualified mechanic or the manufacturer's guidelines if you are unsure about any steps.

Disconnecting the electrical plugs and fuel lines

Begin by jacking up the rear of the car and supporting it securely on jack stands. It is important to never work on a car while it is only supported by a jack. Ensure that the fuel tank is as empty as possible before proceeding. Wear protective eyewear, as gasoline can be harmful to your eyes, and be cautious of any falling objects while working under the vehicle.

Locate the fuel regulator in the engine bay, which looks like a top hat, and relieve the fuel pressure. You will find a Schrader valve on the regulator; place a rag underneath and push in the pin to release the pressure. Do not attempt to start the car after this step, as it will charge the fuel system again.

Move to the rear passenger side of the car and remove the lines from the fuel filter and surrounding area. You will find these lines near the rear passenger door, underneath the car. Use penetrating oil on the quick clips and carefully squeeze and wiggle the lines apart without breaking them.

Follow the lines toward the fuel tank, and you will find three electrical plugs. Unplug these connectors. Please note that the 1997 Bonneville SSEi only has one electrical connector and does not have a pressure sensor on the tank.

Now, go to the driver's side rear and remove the tire. Here, you will find the filler hose and the smaller vapor hose. Loosen the hose clamps and carefully remove the tubes from both sides, starting with the car side and then the tank side. Use a rag to plug the holes in the tank to prevent any spills.

At this point, the fuel tank is free from the car. Remove the strap bolts, and the straps will fall away while still connected to the car. You may need to use a small jack and a piece of wood to support the tank if it is still heavy with gas.

Carefully pull the tank out like a drawer from the driver's side of the car. It will run along the exhaust and fall off, completely free from the vehicle. Now, you have access to the fuel pump assembly. Clean the area thoroughly with air or a vacuum to ensure that no debris falls into the tank.

You will find a ring on the assembly; use a punch or screwdriver to tap it counterclockwise until the notches line up, allowing you to pull out the assembly. Be cautious not to damage the strainer or float during this process. Take your time and gently turn and tilt the assembly until you can remove it through the hole.

Once the assembly is out, inspect the inside of the tank for any debris, pump parts, or rust. Use a magnet to remove any rust particles.

Now, you can disconnect the plug from the fuel pump and carefully wiggle the pump out of the rubber bottom, then pull it off the tube. Depending on your replacement kit, you may need to replace all the rubber components. Reassemble the new pump, ensuring that all connections are secure.

Finally, reinstall the fuel tank and all the components you removed in the reverse order. Apply dielectric grease to the electrical connections on the outside of the tank to protect them. Ensure that nothing is crushed between the car and the tank when reinstalling the straps.

Once the car is back on the ground, turn the key to the charged position a couple of times to recharge the fuel system. Start the engine and carefully check for any leaks or unusual smells. You should now have restored stock fuel pressure.

Removing the old pump and installing the new one

To remove the old fuel pump and install a new one, follow these steps:

Firstly, jack up the rear of the car and support it on jack stands for safety. It is important never to work on a car while it is only supported by a jack. Try to get the fuel tank as empty as possible. Wear protective eyewear as fuel can be harmful to your eyes, and be cautious of anything that may fall from the car while working underneath it.

Once under the car, you will see the straps holding the fuel tank in place. Look for the mounting bolts and soak them with a penetrating oil to help with removal. These bolts can be tricky, so be sure to use an air wrench if possible. Now, move to the engine bay to relieve the fuel pressure. Locate the fuel regulator, which looks like a top hat, and put a rag underneath it. Push the pin in to relieve the pressure. Do not attempt to start the car after this, as it will charge the system again.

Back underneath the car, remove the lines from the fuel filter and the surrounding area. These lines are located near the passenger-side rear door. Use penetrating oil on the quick clips, and carefully squeeze and wiggle the lines apart. Be cautious not to break these lines. Follow the lines towards the tank, and you will find three electrical plugs. Unplug these. Please note that the 1997 Bonneville SSEi only has one electrical connector and does not have a pressure sensor on the tank.

Now, move to the driver's side rear and remove the tire. Here, you will find the filler hose and the smaller vapor hose. Loosen the hose clamps and remove the tubes from both sides, starting with the tube on the car side first. Use a rag to plug the holes in the tank. At this point, the tank is free from the car. If it is still heavy with gas, you can use a small jack and a piece of wood to support it.

Remove the strap bolts, and the straps will fall away while still connected to the car. Carefully pull the tank out like a drawer from the driver's side of the car. It will run along the exhaust and then fall off, completely free from the vehicle. Now, you have access to the fuel pump. Clean the area with air or a vacuum to ensure nothing falls into the tank.

You will find a ring that holds the fuel pump assembly in place. Use a punch or a screwdriver to tap it counterclockwise until the notches line up, allowing you to pull out the assembly. Be careful when removing the assembly to avoid damaging the strainer or float. Take your time and gently turn and tilt it until you can get it out through the hole.

With the assembly out, inspect the inside of the tank for any debris, pump parts, or rust. Use a magnet to remove any rust particles. Disconnect the plug from the pump, and then carefully wiggle the pump out of the rubber bottom and pull it off the tube. Depending on the kit you have, you may be able to replace all the rubber components. Reassemble the new pump, ensuring that the strainer and float are correctly positioned.

Once the new pump is assembled, put the whole thing back into the tank, pushing down the ring, and tapping the lock ring into position. Reinstall the fuel tank and all the components you removed in the reverse order. Apply dielectric grease to the electrical connections on the outside of the tank. When reinstalling the straps, ensure that nothing is getting crushed between the car and the tank.

Finally, turn the key to the charged position a couple of times to charge the system, and then start the car. Check for any leaks or unusual smells. You should now have restored stock fuel pressure.

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