How to Change the Fuel Filter on a 1990 Mazda 626

A car's fuel filter is responsible for filtering out dirt and water in the fuel coming from the gas tank. Damage to the filter happens most often from debris entering the gas tank from service station gas wells. Symptoms of a bad fuel filter include poor fuel economy or sluggish acceleration when the gas pedal is depressed. During the starting phase of the engine, the car may also continually stall out. The fuel filter on the 1990 Mazda 626 is located in the engine compartment, right next to the brake fluid master cylinder.

Things You'll Need

• Socket wrench set
• Black electrical tape
• Shop rag
• Pliers
• Two fuel hose plugs
• Fuel filter

Instructions

Relieving the Fuel Pressure

1. Pop the hood on the car. Locate the black fuse box cover on the right side of the engine compartment. Take the plastic cover off the fuse box. In the top row toward the windshield you will see two black relays. Unplug the relay on the right hand side. Pull it straight out of its location--do not twist or turn it. This is the fuel pump relay. Set it to the side of your work area once removed.

2. Remove the fuel filler cap from the car. Start the engine and let it run until the car stalls out. After the engine stalls, make three additional attempts to start the engine. This will assure you that the fuel pressure has been relieved when the engine fails to start.

3. Disconnect the negative battery cable from its post with your socket wrench. Wrap the metal end of the cable completely with the black electrical tape. Lay the cable down and away from any metal within the engine compartment. The negative battery cable is easily identified by the minus symbol on the top of the battery.

Removing the Fuel Filter

1. Wipe down the area around the fuel filter with a shop rag or towel. Wipe down the fuel filter's hoses as well. Failing to clean the area before the fuel filter is removed risks dirt dropping into the fuel filter's hoses and contaminating the new filter.

2. Squeeze the tabs on the metal retaining clip on the top fuel hose of the filter together, using a pair of pliers. Slide the clip back on the hose three inches. Remove the hose slowly from the fuel filter. Quickly plug the hose to prevent leftover fuel from spilling.

3. Remove the two bolts from the fuel filter's mounting bracket. Slowly move the fuel filter forward from its mounting position. Use the pliers to again slide back the bottom hose's retaining clip three inches. Remove the bottom fuel filter hose and plug it as well.

4. Carefully remove the fuel filter with its mounting bracket still attached from the engine. Make note of the fuel filter's mounting direction in the bracket. There should be an arrow on the filter that indicates the direction the fuel flows through it.

Installing the Fuel Filter

1. Pop the old fuel filter out of its mounting bracket. Place the new filter in its place exactly like you removed the old fuel filter. The arrow on the new filter must be pointed in the same direction as the old fuel filter's was.

2. Place the fuel filter with its mounting bracket attached back into position within the engine compartment. Do not return its mounting bolts yet. Unplug and attach the bottom fuel filter hose. Slide the hose's metal retaining clip back to its original position using the pliers.

3. Hold the fuel filter's mounting bracket in place and return both bolts by hand to ensure proper threading. Completely secure the bolts with your socket wrench. Unplug and reattach the top fuel filter hose. Secure the hose by returning its retaining clip to its original position using the pliers as well.

4. Plug the starter relay back into its location and return the fuse cover. Unwrap the negative battery cable terminal and secure it back onto the battery. Start the car and check the new fuel filter to make sure it isn't leaking. (It may take a few attempts to start the car after the repair. This is because the fuel pressure has to build back up in the fuel system.) Once the car is started, let it run for 20 minutes before test driving.

Tips & Warnings

• Always perform this type of repair in a well ventilated work area.

• Mazda does not endorse auto parts suppliers. For all replacement procedures, Mazda recommends using genuine Mazda parts.

References

• "Chilton's Mazda: 323/MX-3/626/MX-6/Millenia/Protege 1990-98"; The Nichols/Chilton Editors; 1999
• "Haynes Automotive Reference Manual and Illustrated Automotive Dictionary"; John Haynes; 1994
• "Road & Track Illustrated Automotive Dictionary"; John Dinkel; 2000
• "Popular Mechanics Complete Car Care Manual"; The Editors of Popular Mechanics; 2005