Replacing the fuel filter in the 1994 Toyota Corolla is a time-consuming and labor-intensive process. When your Corolla’s fuel filter is clogged, the engine may run rough. Expect to have to replace the fuel filter about once every 30,000 miles or so, depending on your typical driving conditions.
Turn the Corolla’s key to the “Lock” position. Open and support the hood. Disconnect the negative cable from the battery post with your pliers. Wait about 10 minutes to allow the fuel system to depressurize.
Remove the screw from the clamp on the engine air filter hose, then slide the clamp downward. Disconnect the engine air filter hose from the throttle body. Push down the four clamps that secure the top part of the engine air filter box to the bottom part. Unplug the electrical connection attached to the hose. Lift the entire setup, including the hose, out of the engine compartment.
Remove the two hoses from the charcoal canister. This is viewable with the engine-air filter assembly out of the way. Use pliers to loosen the clamp, then pull the hoses away from the canister. Lift the charcoal canister up to remove it from its mounting bracket to access the Corolla’s fuel filter.
Put on a pair of goggles. Place a close-ended wrench on the top fuel filter bolt, then place an open-ended wrench around the bolt beneath it. Cover the fuel filter with a shop rag. Hold the lower open-ended wrench steady. With your other hand, turn the close-ended wrench on the top fuel filter bolt counterclockwise to remove it. A small amount of fuel may leak out.
Lift the top fuel filter bolt from the fuel filter. Remove the two gaskets and the inlet fuel hose. Remove the two fuel filter mounting bolts with a socket wrench set. Lift the fuel filter out of the engine compartment.
Insert the new fuel filter in its place. Tighten the two mounting bolts to secure it. Re-assemble the bolt above the fuel inlet line and replace the two gaskets. Hold the open-ended wrench on the bottom bolt while tightening the top bolt with the close-ended wrench.
Re-insert the charcoal canister into its mount. Attach the two hoses to the canister, using the pliers on the clamps to secure the hoses to the canister.
Re-insert the engine air filter assembly into place. Clamp down the top portion to the bottom portion using the flip clamps. Attach the hose to the throttle body. Push the clamp upward and tighten its screw to secure it. Plug the electrical connection back into the hose to finish.