Relieving fuel pressure.

[SnakeKack]

I was wondering where I relieve the fuel pressure at. I'm changing my fuel filter, and I have only changed CB. never a FI.

I'm sure someone can help me on that.

Also my filter I have on my car is a cylinder and its flat on top and on bottom and my new on is flat on one side and pointed on the other. Which side goes up and which side goes down?

[Dousan_PG]

take your gas cap off
pressure relieved.

for the filter, should have an 'in out' marking or blow on it
sometimes can tell
ususally the 'ramped side' goes down. iirc
z32 filter is cheaper then s13 often from dealer
and its bigger, but still fits fine w/ a little work.

[g6civcx]

What is the make and model of the car, please?

[SnakeKack]

1993 Nissan 240sx

[matt4pl]

pull out the fuel pump fuse, run the car til it dies, remove gas cap, change filter, re-install everything, turn key to on without starting the car a few times to rebuild pressure, start car, check for leaks

[slideways2004]

i just do the gas cap. fuek filter takes like 3 min. if installed backwards, what would happen?

[Dousan_PG]

exactly removing fuse is a hassle though easy, yes but does the same thing as the other way
what would happen? no idea. i dont know.

[g6civcx]

Okay, for an S13 you may use the fuel filter for the 90+ 300ZX. It's bigger, but will fit in the bracket if you bend it out a little bit. The flat part of the 300ZX filter goes on top for the outlet and the round part goes on the bottom for the inlet.

While you're at the store, go ahead and get new hose clamps for the fuel hose as well. The old hose clamps are very hard to work with. The smallest size should fit the fuel hose. Also, depending on the condition of your fuel hose, you may want to replace it if it's older than 5 years, or show visible signs of wear.

1. Wait until the car is cool because you don't want to work with a hot engine bay. Don't smoke, and keep a Type B fire extinguisher just in case.

2. Start the car and let it idle.

3. Go to the underhood relay box A. It's next to the battery. Remove the lid and look for the fuel pump fuse. It's a 15A fuse in the middle column, 2nd from the right. Pull that fuse. The car will die as it runs out of fuel.

4. Unscrew the fuel filler cap to vent pressure.

5. Remove the negative terminal of the battery. You can also remove as a precaution as well to prevent sparks.

6. The fuel filter is located next to the passenger strut tower, slightly lower than the battery. It looks like a little cup.

7. Use pliers/vice grip, a screwdriver, or a socket as approriate to remove the hose clamp on top of the filter. Gently pull the hose out from the filter. If you have trouble removing it, try not to damage the hose or fitting as you pull. There's a hose removing tool you can get. It's similar to vice grips with rubber ends to prevent damage. At this point some fuel may start pouring out so get some old rag to soak it up.

8. Remove the filter from its mount.

9. Remove the fuel line from the bottom in the same manner.

10. Installation is the reverse of removal. Install new hose clamps and hoses if necessary. Make sure everything is tight and there is no leak. Replace the fuel filler cap, the 15A fuel pump fuse, and the battery connection. Clean up any fuel before proceeding.

11. Turn the key to ON and wait several seconds for the fuel pump to prime. Then you may start the car and check for leaks. Turn off the ignition immediately if you have leaks.

That should be everything you need. Good luck.

[g6civcx]

Here are pix for a side-by-side comparison. I believe that if you hook it up backward, it may clog and reduce fuel pressure. If the filter is dirty, all the contaminants will also be introduced to the fuel rail.

[wootwoot]

Just a note, in the 4 garages I have been around in (working at two) everytime anyone(including me) does a fuel filter you just unscrew the cap. Everything else is nice and all but its more work that you dont need to do

[g6civcx]

You don't have to relieve fuel pressure. The catch is more fuel will be released when you remove the fuel filter. Extra fuel means extra risks for fire.

Proceed accordingly.

[Dousan_PG]

Originally Posted by g6civcx

You don't have to relieve fuel pressure. The catch is more fuel will be released when you remove the fuel filter. Extra fuel means extra risks for fire.

Proceed accordingly.

not releive pressure can be messy
didnt on a friends car, gas wouldnt stop coming out till we popped the tank open. thats why you relieve it

such an easy task. takes 10 mins. max.

[SnakeKack]

Thanks guys, I really apreciate the info. I'll probably change it after I get back from work tomorrow. BTW g6civcx the two pics of the filter you show, the bottom filter looks almost the same as my new one. Which side is up and which is down?

[g6civcx]

All high-quality fuel filters should have a flow indicator to let you know which is in and which is out. From my experience, the flat side should go up, but check with the manufacturer of your particular filter to make sure.

Don't always assume the direction by the shape. Look for markings. If you can't find it, ask the store people. If they don't know, buy another brand.

FYI, fuel goes in from the bottom and comes out at the top. You can tell because the top hose goes straight to your fuel rail.

Nissan uses clamp-on fuel hoses. They're easier to remove but may leak if installed incorrectly or if the fittings are worn. Other manufacturers use banjo bolts which are more secure, but harder to remove since they tend to rust.

[Dousan_PG]

what type of filter did u buy?
i bought a pos fram one for my beater s13
flat side up, ramped side down.