Ford Mustang 1989-1993 Repair Guide

Fuel Filter


The fuel filter on the Mustang is normally found under-vehicle, near the fuel tank mounted to the rear crossmember.


See Figures 1 and 2

Fuel is filtered at 3 separate locations on these vehicles:

Fuel pump inlet filter
In-line fuel filter
Injector filter screen

Of these 3 fuel filters, only the in-line type has ever really been considered a maintenance item. The others are expected to serve the life of the components to which they are attached. But even the in-line fuel filters have become more efficient, so no periodic replacement interval is recommended by the manufacturer. It is never a bad idea to replace the filter on a older vehicle or a used vehicle where the quality of gasoline which may have been used in the car is not a known item. Likewise, any vehicle that shows signs of fuel filter clogging (such as hesitation or stumbling on acceleration which cannot be traced to the ignition system or other fuel system components) is a good candidate for an in-line filter replacement.

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Fig. Fig. 1: In-line fuel filter assembly mounting

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Fig. Fig. 2: Cross-sectional view of a fuel injector showing the inlet screen

Fuel Pump Inlet Filter

A nylon filter element is attached to the electric fuel pump inlet inside the fuel tank. It is used to protect the fuel pump from possible tank contaminations.

In-Line Fuel Filter

The in-line fuel filter is designed to filter material which could damage the tiny metering orifices of the injector nozzles. The filter is located downstream of the electric fuel pump and is usually mounted to the rear crossmember. The in-line filter is of one-piece construction, meaning that it cannot be cleaned and must be replaced as an assembly should it become clogged. Because flow will vary between filter elements, be sure to only use the proper replacement part which is designed for your engine's fuel system.

Fuel Injector Filter Screen

Each fuel injector contains a filter screen at the top (fuel inlet point). If the injector screen becomes clogged, the complete injector assembly must be replaced.


See Figures 3, 4 and 5

Never smoke when working around or near gasoline. Make sure that there is no possible ignition source (such as sparks or open flames) near your work area.

In-Line Filter

To prevent the siphoning of fuel from the tank when the filter is removed, raise the front of the vehicle slightly above the level of the tank, but be sure to properly support the vehicle using jackstands. Fuel line clamps may be used to prevent leakage, but ONLY WITH CAUTION. Old, brittle fuel lines may be damaged by the clamps and could leak afterwards. If a clamp is used, BE SURE to thoroughly inspect the lines after installation of the fuel filter. Any damaged line should be immediately replaced.

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Fig. Fig. 3: Though fuel line clamps can be used to prevent leakage, MAKE SURE the line is not damaged

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Fig. Fig. 4: Once the hairpin clip is removed, the push-connect fitting may be disengaged from the filter

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Fig. Fig. 5: If you have trouble getting to the push-connect fittings, try loosening the worm clamp and repositioning the filter slightly for access.

  1. Disconnect the negative battery cable.
  3. Properly relieve the fuel system pressure using a test gauge at the fuel pressure relief valve. For more details, please refer to Fuel System of this repair guide.
  5. Raise and safely support the vehicle.
  7. Remove the push-connect fittings at both ends of the filter (for details on push-connect fitting removal, please refer to Fuel System of this repair guide). Install new retainer clips in each push-connect fitting.

Position a rag below the filter to catch any fuel which may spill as it is disconnected and removed.

  1. Remove the fuel filter from the bracket by loosening the worm gear clamp. Note the direction of the flow arrow as installed in the bracket to ensure proper direction of fuel flow through the replacement filter.

To install:
  1. Install the fuel filter into the bracket, ensuring the proper direction of flow. Tighten the worm gear clamp to 15-25 inch lbs (2-3 Nm).
  3. Install the push connect fittings onto the filter ends. Start the engine and check for leaks.

Use extreme caution when starting and running an engine which is supported by jackstands. MAKE SURE no drive wheels are on the ground. Also, be sure that the wheels which are on the ground are properly blocked so the vehicle cannot move.

  1. Lower the vehicle.