How to change the In-Tank Fuel Filter

The Forgotten Filter
by Tom Mak


DISCLAIMER: Since this How-To requires opening the fuel tank, MARX7.org and Tom Mak are NOT responsible for any damages which may result from performing the actiosn explained on this page.
If you decide to perform these actions, this page is meant as a rough guide and is not exacting.
PLEASE take care when performing the actions described on this page, and keep open flames and sparks away from the open fuel tank.
After 155K miles in my '90 GXL, my car got it's in-tank fuel filter changed for the first time.
After changing it, I noticed little gain in gas mileage.

Here is what you will need:
  • Philips screwdriver
  • Flathead screwdriver
  • Needle nose plier
  • Fuel pump filter - I paid like 6 bucks through Mazda Comp
  • Screw that screw the fuel filter holder onto the frame (I stripped mine, don't know what kind of luck you will have)
  • A little o-ring that clips the fuel filter onto the frame, this is very important.
    I RECOMMENED THAT YOU REPLACE THIS O-RING. You have to get the part # on this.

Here is what you will have to do:
  1. Lift up the carpet in the back and put it in the front so you can gain access to the fuel pump.
  2. Fuel pump is under a silver plate on the left rear side of the car.
  3. Remove the 4 screws that hold the plate down, it’s a Philips head screw.
  4. You should see the fuel pump bolt down onto the tank.
  5. Now start the car and unplug that white connector on top of the pump and let it stall out so you can release the fuel pressure.
  6. Remove the 2 fuel lines on the fuel pump, watch for splash fuel.
  7. Unscrew all these little small Phillips head around the pump.
  8. Pull the unit out.
  9. Unscrew that Philips head screw at the very bottom, be careful, it is on TIGHT!
  10. Now you will have access to the fuel filter, but you have to remove that little o-ring that holds it down. I suggest you get a new one so you can make this easy on yourself.
  11. You are all set and enjoy.
Installation is reverse as removal.

written by: Tom Mak