Replacing Fuel Filter In '99 Miata: Step-By-Step Guide

Changing the fuel filter on a 1999 Miata can be a challenging task. The process involves removing the plastic cover, loosening the clamp, detaching the old retainer clip, and connecting the new filter. While it is a straightforward procedure, it is important to take precautions to avoid gasoline spillage and ensure safety. Some people have shared their experiences of getting drenched in gasoline during the process, highlighting the importance of clamping the fuel hoses and having a bucket ready to collect any spillage. Additionally, wearing protective gear, such as long rubber gloves and safety goggles, is crucial to safeguard against gasoline exposure.

Locating the fuel filter

The fuel filter is in the middle, forward of the rear passenger-side wheel, and towards the center. The plastic cover is held in place by 4 or 5 plastic-type screw clamps, which frequently become stripped. Use a knife to pry them out slightly, and use a cross-tip screwdriver to remove them.

Once the cover is removed, you will see the clamp, which you should loosen and bend out of the way. You will also see the intake and exit hoses, which will need to be removed and attached to the new filter.

Before beginning any work, it is important to relieve the pressure in the fuel system. Removing the fuel cap relieves pressure in the fuel tank and return fuel line, but there will still be pressure remaining at the fuel filter. To further depressurize the system, with the engine at idle, disconnect the yellow Circuit Opening Relay (1.6) or Fuel Pump Relay (1.8) under the dash near the steering column. The engine will stall, and you can then replace the plug and switch the ignition key to the off position.

Now that you have located the fuel filter, you can begin the process of changing it.

Disconnecting the fuel pump relay

Firstly, locate the fuel pump relay. In the 1999 NB Miata, the fuel pump relay is situated under the steering column, right above the accelerator pedal. It is important to note that the clip colour may vary, but it is typically bright yellow.

Once you have located the fuel pump relay, the next step is to disconnect it. This can be done by unplugging the relay or, if necessary, removing it from its bracket and then disconnecting it. This process will require some dexterity, as the space may be tight and the relay may be difficult to reach.

Before disconnecting the fuel pump relay, it is crucial to relieve the pressure in the fuel system. Removing the fuel cap will help to relieve some pressure, but it is important to note that there will still be significant pressure remaining. To fully depressurize the system, turn the engine to idle and disconnect the yellow plug under the dash near the steering column. This plug is either the Circuit Opening Relay (1.6) or the Fuel Pump Relay (1.8), depending on your model. Disconnecting this plug will cut power to the fuel pump, causing the engine to stall. Once the engine stalls, replace the plug and turn the ignition key to the "OFF" position.

At this point, the fuel lines will still be filled with fuel and will need to be handled carefully. It is recommended to wrap a rag around the filter line when twisting the first fuel line loose, as this will help to absorb any fuel that may leak out.

Now, you are ready to proceed with disconnecting the fuel pump relay. Carefully unplug the relay or remove it from its bracket, being mindful of any surrounding components. Ensure that you have enough clearance to work comfortably and that you are wearing appropriate protective gear, such as gloves and goggles.

Once the fuel pump relay is disconnected, you can proceed with the next steps in changing the fuel filter. Remember to work in a well-ventilated area and have all your tools easily accessible to make the process smoother.

Removing the plastic shroud

First, locate the fuel filter cover. It is positioned in front of the rear wheel on the passenger side of the car. The cover is held in place by 4 or 5 plastic screw clamps. These clamps can become stripped or damaged over time, so be careful when removing them. Use a knife to gently pry them out slightly, and then use a cross-tip screwdriver to unscrew them completely. If any of the clamps are broken or missing, you can purchase suitable replacements from your local auto parts store.

Once you have removed all the clamps, set them aside and carefully lift off the plastic shroud. With the shroud removed, you will have clear access to the fuel filter and the associated fuel lines. Before proceeding, make sure to depressurize the fuel system to avoid any accidental spills or injuries.

Now, let's focus on the fuel lines. You will notice that they are connected to the fuel filter by hose clamps. Loosen these clamps with a suitable tool, such as long-nose vise-grips or pliers with a rag wrapped around the jaws to protect the hoses. Be cautious, as the fuel lines may be stuck on tightly. Do not completely remove the lines; simply loosen them enough so that they can be easily detached by hand later on.

At this point, the plastic shroud and its associated clamps have been successfully removed, providing access to the fuel filter for replacement. Remember to handle the exposed fuel lines with care and be prepared to catch any dripping fuel. It is recommended to have a drip pan or container ready to collect any spilled fuel during the filter replacement process.

By following these steps, you can safely and effectively remove the plastic shroud on a 1999 Miata, allowing you to access and replace the fuel filter with ease.

Using a disconnect tool

Disconnect tools are available in sets from various auto parts stores, including NAPA, Harbor Freight, AutoZone, and O'Reilly Auto Parts. The sets typically include multiple sizes to accommodate different vehicle makes and models. When working on a 1999 Miata, the 5/16" or 3/8" tool is typically recommended. The plastic tools are generally thinner and easier to use in tight spaces than the metal ones.

To use the disconnect tool, slide it onto the fuel line and push it up to the connector. This will release the lock, allowing you to slide the fuel line off. For the 1999 Miata, it is important to use the correct size and type of disconnect tool to avoid damage to the fuel line and retaining clips.

When replacing the fuel filter, it is also recommended to have new retaining clips available. These can be purchased from auto parts stores and installed on the new fuel filter before connecting the fuel lines. This will help ensure a secure connection and reduce the risk of fuel leaks.

Replacing the retaining clips

To replace the retaining clips of a 1999 Mazda Miata's fuel filter, you will need a 10mm wrench for opening the filter retaining clamp, replacement hose retainer clips, long-nose vise-grips, and a knife or something with a blade to pry out the plastic cover screws.

First, make sure you are wearing the appropriate safety gear, including gloves and protective goggles. Then, depressurize the fuel system. Next, take off the plastic cover concealing the filter. Once the cover is removed, the clamp loosened, and bent out of the way, ready a new retainer clip on the intake side (the short horizontal pipe) of the new filter. Now, use pinch-nose pliers to detach the old clip, and quickly put the dripping hose onto the new filter, ensuring the other end of the filter is clamped or plugged. Once the hose is on, carefully move the old filter out of the way.

Now, remove the exit hose and attach it to the new filter. Place the new filter into the clamp, bend the clamp arms back into place, and use the long-nose vise grips to hold it together while screwing in the clamp bolt. Finally, replace the cover, plug in the FPR, and make sure it turns on.

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