Is it hard to change the fuel filter on a 1997 Infinity QX4?

No... not hard at all. NO special TOOOOOOOLS required, that's some mechanic's BS)
Fact is....you'll at most need: a pair of plyers to hold the hoses as you finally remove (rip out!) the old filter; A Phillips(crosstop) screw driver; and/or a Common (flat/blade) screw driver to loosen the fuel hose clamps that are clamping onto the filter's hoses itself; AND a 10mm socket on the end of a very long extention ( or several smaller extentions connected together inorder to equal about 16''-20'' of total extention) in order to reach the fuel filter's mounting bracket (Looks like a big "U" shaped bracket that clamps the filter to the underside of the vehicle. The bracket's (hex) bolt head (some models have a combo... phillups/hex headed bolt, WHICH CAN enable you to use a super long phillups screw driver) but it's best to use a rachet and a 10 mm socket with a super long extention SINCE THE filter's mounting bracket CAN BE VERY TIGHT).

Sorry... enough digression!

1: Loosen the fuel filter's hose clamps,
2: Slide clams down the line about 2 inches from the filter,
3: Loosen and remove the filter's retaining bracket bolt.

3: STOP>>>>>>>> NEXT IS TO PROTECT YOUR EYES FROM SPRAYING FUEL (GAS )! because as you
4: Pull and the (pressurized) fuel line apart from the filter

IT WILL DEFINATELY SPRAY A LIL to a LOT.
Regardless, it will depressurize and then you can
Rip the filter tips from the lines (use plyers to hold the line as you twist and rip the filter out of the rubber fuel line...if that's what it takes RIP IT from it's rubber hose, but try not to damage the rubber fuel line too much as you'll need to attach the new filter to it!

The filter is about 4"-6" long. It's located near the edge of the spare tire housing (under vehicle, 1/4th the way in from the rear bumper, bracketed to the underside, just about on "centerline" of the vehicle...you can't miss it! Small, shinny, metal canister with two hoses connected to it and one bracket retaining it (the fuel filter) to the underside of the vehicle. One hose connected to the "IN" one to the "OUT" of the Filter ! Yes, the filter is directional !

Yes, It must be reinstalled correctly...."IN" ( of the filter) "comes from the QX4'S fuel tank line" (Tank is easy to see...about 1 foot away towards the Drive's side of the vehicle ). "OUT" (of the filter) "connects to the engine's fuel line" leading towards the Passenger's side hose (which eventually connects to the QX4's engine about 12 feet away)

This swisted procedure should get you through it if you read it properly.

It'll take 1 - 4 hours depending on skill/tooling/and replacement filter in-hand ability.

Lastly, start mid-morning, take your time, relax take breaks if needed and by early evening you'll be done.
Hope this helped...best of luck
Gz

Gz
January 2009