How to replace your fuel filter:
It’s on the passenger side of the engine bay attached to the strut tower about halfway down. It looks like a little silver can with one black hose going into the top of it and one black hose coming out of the bottom.
Take off the gas cap, take out the fuel pump fuse in the fuse box by your battery. It should show you where it is on the cover. (Note: Fuel Pump fuse is in fuse box by left foot in the S14.)
Crank the engine and it should start, then immediately die. Loosen the clamp on the top hose and slide the clamp up on the tube, then tighten it so that it squeezes the tube shut a bit (not too much to rip the tubing!!), then do the same for the lower tube. It might be tough to get off because the filters have nipple like plastic tubes coming off the filter that can seize to the rubber fuel tubing a bit because the tubing gets hard over time. It took some effort to get the tubing off. (Note: Twist the fuel filter while holding the tubing. The twisting will help loosen the connection. Pulling straight out will only result in cut knuckles or a sore elbow. Resist the urge to use pliers on the tubing, it’ll damage them and cause a leak.
Once they are off some gas will spill out so I’d put a old rag or towel underneath the filter to absorb any gas that spills.Now would be a bad time to light a cigarette.
Then put the new one in and attach the hoses. Re-tighten the clamps where they were on the original. Overall if the tubing comes off easily, it’s a 15-20 minute job.
TIP:The 300ZX fuel filter fits the 240sx fine and is a bit less restrictive (for those of you running boost).