The 1990 Ford Ranger has an inline fuel filter that keeps sediments out of the engine. The fuel filter is designed to trap and hold any sediments from the gas before the fuel reaches the fuel injectors and the engine. The fuel filter on the 1990 Ford Ranger is designed to last up to 75,000 miles. You'll need to replace it after that.
Park the 1990 Ford Ranger and turn the engine off. Unscrew the gas cap.
Locate the fuel filter. It's on the driver side of the 1990 Ford Ranger. The fuel filter is inside a round bracket that is mounted inside the driver-side frame rail directly under the driver door. The fuel filter has two fuel lines. There is one fuel line coming out of each end of the fuel filter. This type of fuel filter will require a fuel line quick-disconnect tool that can be bought a most auto parts stores.
Put the gas catch pan under the fuel filter. There should be only a small amount of excess gas in the gas lines.
Insert the tool inside the end of the fuel line that is attached to the fuel filter port. Push the tool in until the fuel line unlocks from the fuel filter port on the fuel filter. When the fuel line unlocks from the port, pull the fuel line straight off the port. Follow this method for both fuel lines.
Remove the fuel filter from the round bracket. Pull the fuel filter out with your hands and put the fuel filter into the catch pan.
Slide the new fuel filter into the round bracket. Make sure the arrow that is imprinted on the side of the fuel filter is pointing toward the front of the Ranger. The arrow represents the direction of the fuel flow.
Push both of the fuel lines straight onto the fuel filter ports until the ends of the fuel lines lock onto the fuel filter ports of the fuel filter. To ensure that the fuel lines are locked in place, pull back on the fuel lines.
Screw the gas cap back onto the gas tank. Prime the fuel filter by turning the key on and off three times.
Crank the 1990 Ford Ranger and look over the new fuel filter for any gas leaks while the engine is running.
Turn the engine off and slide the catch pan out from under the 1990 Ford Ranger.
