Replacing Fuel Pump In Mazda 626: Step-By-Step Guide

The Mazda 626 is a popular car model that has been around for decades, with multiple generations floating off Mazda assembly lines worldwide. If you own a Mazda 626 and are experiencing issues with your fuel pump, it may be time to consider a replacement. A faulty fuel pump can cause various problems, including difficulty starting the engine, diminished engine performance, and even complete engine failure. While it is possible to replace the fuel pump yourself, it is highly recommended to seek professional help due to the dangers of dealing with gasoline. This article will provide a step-by-step guide on how to change the fuel pump in a Mazda 626, including locating the pump assembly, verifying the fuel pump relay and fuse, and conducting a road test to ensure the new pump is functioning correctly.

How to access the fuel pump

To access the fuel pump in a Mazda 626, you will need to locate the pump itself, which is situated inside the fuel tank. There is no access point to reach the pump without removing the fuel tank.

However, some people have chosen to create their own access point by cutting a small hole through the bodywork under the rear seat. This is not recommended as it is not a clean job, and you risk damaging the fuel lines or tank, which contains flammable liquid.

If you choose to drop the fuel tank, you will need to remove the rear seat first. There are two push clips under the passenger and driver's front of the seat. Once these are removed, you will see a metal plate with four screws holding it in place. The fuel pump is located under this plate.

Before removing the pump, there are some tests you can perform to ensure that the pump is faulty. First, check the wiring to the tank to ensure there is power to the pump. You can also test the fuse and the fuel pump relay. If these are good and you still have no fuel pump function, then you can proceed to replace the pump.

Removing the fuel pump assembly

To remove the fuel pump assembly from your Mazda 626, you will first need to park your car on a level surface and engage the parking brake. Next, locate the pump assembly in the fuel tank—you can do this by turning the key to the 'on' position and listening at the filler opening for a hum that should last 2-3 seconds. If you don't hear this, it's likely that the pump needs replacing.

Once you've located the pump, you'll need to verify the vehicle's fuel pump relay and fuse. If the fuse is damaged, replace it with a new one of the same amperage. Now, check the fuel pump's operation. If it's working, you've resolved the issue. If not, and the fuse and relay are functioning, you'll need to check for power and ground at the fuel pump. If there's power and ground, the pump is flawed and needs replacing.

The next steps involve relieving the fuel system pressure and disconnecting the negative battery cable. Drain as much fuel as possible from the tank, and disconnect the filler fuel hose and the electrical connection to the old pump. Support the fuel tank using a jack stand and a block of wood, and remove the entire pump assembly, including the pump and the fuel level sending unit.

Now, you can remove the fuel pump itself. Remove all hose clamps, disconnect the fuel line or fuel tank hose, and extract the pump from the tank.

It's important to note that working with fuel and electricity can be dangerous, and it's recommended that you hire a professional mechanic to perform this task.

Disconnecting the fuel pump

Before beginning any work on your Mazda 626's fuel pump, it is imperative to take necessary safety precautions. Park your car on a level surface and engage the parking brake. Fuel is highly flammable, so exercise extreme caution throughout the process.

To start, relieve the fuel system pressure and disconnect the negative battery cable. This is a critical safety measure to prevent any accidental ignition. Next, drain as much fuel as possible from the fuel tank. This step will reduce the risk of spillage and minimize the amount of flammable liquid present.

Once the initial safety measures are complete, you can begin to access the fuel pump. Disconnect the filler fuel hose and the electrical connection to the old pump. These connections are what provide fuel and power to the pump, and they need to be carefully detached.

Now, you'll need to support the fuel tank using a jack stand and a block of wood. This step is crucial as it ensures the tank's stability and safety while you work. With the tank securely supported, you can proceed to remove the entire pump assembly, which includes the pump itself and the fuel level sending unit.

At this point, you have successfully disconnected the fuel pump from your Mazda 626. The next steps would involve extracting the old pump from the gas tank and installing the new one, but those steps are beyond the scope of your request. Remember to exercise caution and follow established safety protocols throughout the process.

Installing the new fuel pump

First, park the car on a level surface and engage the parking brake. It is important to work on a flat surface to ensure the car does not roll and cause accidents or injuries. Next, locate the pump assembly in the fuel tank. This can be done by having someone turn the key to the "ON" position while you listen at the filler opening. A functional fuel pump should produce a soft hum for 2-3 seconds.

Once the location of the pump assembly is confirmed, the next step is to verify the fuel pump relay and fuse. If the fuse is damaged, replace it with a new one of the same amperage. Now, check if the fuel pump is working. If the pump is operational, the issue is resolved. If not, and the fuse and relay are functioning, check for power and ground at the fuel pump.

If there is power and ground, the old pump is faulty and needs to be replaced. Before removing the old pump, relieve the fuel system pressure and disconnect the negative battery cable. Drain as much fuel as possible from the tank, and disconnect the filler fuel hose and the electrical connection to the old pump.

Now, support the fuel tank using a jack stand and a block of wood. Remove the entire pump assembly, including the pump and the fuel level sending unit, and carefully lower the tank. Remove all hose clamps, disconnect the fuel line or fuel tank hose, and carefully extract the old pump from the tank.

Compare the new fuel pump with the old one to ensure you have the correct part. Once verified, install the new pump by connecting all the fuel lines. Reinstall the straps and bolts, and reconnect the filler fuel and electrical connector. Finally, reconnect the negative battery cable.

Fill the gas tank and conduct a road test to ensure the new pump is functioning correctly. It is recommended to get the clogged fuel filter changed when replacing the fuel pump to avoid further issues.

Testing the new fuel pump

Step 1: Park the Car and Locate the Pump Assembly:

Start by parking your car on a level surface and engaging the parking brake. The fuel pump is located inside the fuel tank, so you or a mechanic will need to find the pump assembly in the tank.

Step 2: Listen for the Fuel Pump Hum:

Turn the key to the "ON" position and listen carefully at the filler opening. A properly functioning fuel pump should produce a soft hum for 2-3 seconds. If you don't hear this sound, it's a clear indication that the pump needs to be replaced.

Step 3: Verify the Fuel Pump Relay and Fuse:

Next, locate and verify the fuel pump relay and fuse. If the fuse is blown or damaged, replace it with a new fuse of the same amperage. This step ensures that the fuel pump is receiving the necessary electrical power.

Step 4: Check the Fuel Pump Operation:

Now, check if the fuel pump is working. If it operates as expected, the issue is likely resolved. However, if it doesn't work, and the fuse and relay are functioning correctly, proceed to the next step.

Step 5: Check for Power and Ground at the Fuel Pump:

Verify if there is power and ground at the fuel pump. If there is power and ground, it confirms that the old pump is flawed, and you should proceed with installing the new fuel pump.

Step 6: Prepare for New Fuel Pump Installation:

Before installing the new fuel pump, there are a few important steps to take. First, relieve the fuel system pressure and disconnect the negative battery cable. Then, drain as much fuel as possible from the fuel tank to minimize the risk of spillage during the installation.

Step 7: Compare and Install the New Fuel Pump:

Compare the new fuel pump with the old one to ensure you have the correct part. Then, carefully install the new fuel pump by connecting all the necessary fuel lines and hoses. Make sure to follow the exact installation steps provided by the manufacturer for your specific Mazda 626 model.

Step 8: Reinstall Components and Reconnect the Battery:

Once the new fuel pump is installed, reinstall any straps and bolts that were removed. Reconnect the filler fuel hose and the electrical connector. Finally, reconnect the negative battery cable.

Step 9: Fill the Gas Tank and Test Drive:

Fill the gas tank and take your Mazda 626 for a road test to verify the success of the new fuel pump installation. Pay attention to how the engine performs, and listen for any unusual noises. If the car runs smoothly and there are no issues, your new fuel pump is functioning correctly.

Additional Testing Methods:

Using Starting Fluid to Test for Lack of Fuel:

Another method to test for a lack of fuel is to use starting fluid. First, remove the intake air duct from the throttle body. Open the throttle plate and spray starting fluid down the bore. Reconnect the air duct, then crank the engine. If the engine starts and runs for a few seconds before dying, it confirms a lack of fuel. If it doesn't start at all, the issue is likely not related to fuel supply.

Checking Fuel Pressure with a Fuel Pressure Gauge:

You can also use a fuel pressure test gauge to check the fuel pressure. Connect the gauge to the designated port and read the pressure. Compare this reading to the recommended fuel pressure in your owner's manual. If the pressure is low, it could indicate a faulty fuel pump or a damaged gasket sealer.

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