Fuel Filter Replacement How-To-Write Up - DISCUSSION THREAD
 

This is a write up on how to replace your fuel filter. This goes for Second Generation 2wd, 4wd, 4dr, 2dr, and ZR2 Blazers. It may work for earlier vehicles, but maybe slightly different. The process is similar for most vehicles too.

Tools needed:
* 16mm open end wrench
* 15/16" or 21mm open end wrench
* 13mm socket
* Pliers (to squeeze front fuel line fitting off)

First step is to relieve the pressure in the fuel system. There are two ways to do this. Personally I would use the first method since it is easiest and cleanest.

1A Go under the hood and open the main fuse block. You will need to locate the fuel pump relay and remove it. See the pictures below:

http://i106.photobucket.com/albums/m..._IMG_2176x.jpg

http://i106.photobucket.com/albums/m..._IMG_2177x.jpg

Make sure you remember the direction that the relay goes into the fuse block. Next go try to start your truck and let the engine starve for gas. Once it will no longer turn on, the gas line pressure has been relieved.

OR

1B Go under the hood and find the Schrader valve located behind the air intake and throttle body (see picture below). Take a flat blade screwdriver and depress the middle portion of the Schrader valve, make sure to catch the gas that will fly out of the valve with a towel or cup. Once the gas stops coming out of the Schrader valve, the fuel pressure has been relieved.

http://i106.photobucket.com/albums/m..._IMG_2178x.jpg

Second step is to jack up or raise the front of the vehicle and place jack stands and chocks behind the wheels.

Third step is to start removing the nuts on the back side of the fuel filter. You will need two wrenches (a 16mm and 15/16" (or 21mm) open end wrenches). The larger wrench is just to hold the filter in place and then loosen the rear nut with the 16mm wrench. Once loose enough remove the rest of the way with your hand. Then be prepared with a container to catch the gas (a tin can from having canned vegetables works great).

http://i106.photobucket.com/albums/m..._IMG_2179x.jpg

Fourth step is to remove the fuel filter bracket bolt (13mm socket and a small extension). After that, pop the bracket loose from the fuel and brake lines above. Then pull the filter and front fuel line around the other side of the torsion bar and allow to hang down.

http://i106.photobucket.com/albums/m..._IMG_2180x.jpg

Fifth step is to use your hands to squeeze the plastic clips holding the filter onto the front fuel line and pull filter from the front fuel line (this will release a little more fuel).

http://i106.photobucket.com/albums/m..._IMG_2182x.jpg

Sixth step is to finish draining all the gas from the filter and then pry the bracket off of the old fuel filter. Next test fit the filter in the bracket. If it is super snug cut off some of the tangs inside the bracket then just push the bracket to the middle of the filter.

http://i106.photobucket.com/albums/m..._IMG_2184x.jpg

Seventh step is to reinstall which is the reverse of removing the filter. Once everything is back in place, reinstall the fuel pump relay under the hood. When going to start your truck, turn key to run position and allow the fuel pump to pressurize. Then try starting, it will take about 10 seconds for the engine to start and run properly, so dont worry if it doesnt start right up. Afterwords it should start right up like normal. On the initial startups check for fuel drips/leaks at the fuel filter. If there is a leak, turn off engine and make sure all fittings are tightened properly, then try it again.

Now you are all done and have a nice clean new fuel filter. Enjoy. Any questions PM me or post in the discussion section.

*Edit by swartlkk* - Fixing the clipping problem.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

pain in the butt... getting these off.... you can tell that these were put on the frame before the body was set on at the factory... changed mine and got sooo pissed... but awesome how to do this... props....

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Yeah it wasnt too bad, just had to figure out how to get the dang brake and fuel lines off the top of the filter bracket and to get the new filter into the bracket.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

thanks for the how to. I'm sure it will be used lots.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

I have Never in my fuel filter changing travels ever touched the "Main-Block-Fuses"..is this really a neccessary project within projects?..i only pressed the relief valve to relive pressure.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Pressure valve is my method, but someprefer to pull the fuse.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

If you pull the relay all you have to do is start the truck and it will stop running once the fuel pressure is relieved. It just makes it so you dont have to deal with spraying gas in the engine compartment. Either method works fine, and the relay is very easy to remove. Its all just personal preference, hence why I posted about both methods.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

when i did mine i didnt know you had to rel. pressue on it... i just disconected it from the fuel line, and maybe 1/4cup came out not much at all, and it just dripped out no spay, but next time i will do it the right way..

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

The fuel test port on my Rainier is back at the filter. I installed my fuel pressure gauge (with bleed hose) and I had almost a pint of fuel come out. Still got some fuel out of it when I pulled the filter, but this filter is just two snap fittings and a single screw for the clamp. Quite easy to replace!!

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Yeah the blazer has been the easiest vehicle I have replaced a fuel filter on out of 6 vehicles (not all mine only 3). Yeah I was reading that the new trailblazer, rainer, envoy chasis setup had a very nice and easy location for removing the fuel filter and depressurising the fuel system.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Only problem is instead of working from up top, you're laying on your back when you hook up to the fuel pressure test port. Gasoline doesn't taste all that great![:'(] LOL... I did have my safety glasses on though!

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

The line on the back of my filter is so dang tight I cant get it loose to change it.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Spray some pentrating oil on it, letting it sit for 10 mins, and make sure you are wrenching on it in the correct direction. Good Luck, sometimes those suckers are just rusted a little on the threads and you can't see that part. Thats where the pentrating oil comes in. I would use liquid wrench or PB Blaster, it works wonders.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Will this method work for a 2005 chevy trailblazer and can you tell me the location becasue I cannot fine it.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

the 97+ models have the snap on fitting on front side but 96- they have both bolt on ends :-( lol

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

I am not sure where it is on the trailblazer but the replacement technique should be about the same. The fittings maybe slightly different which is where the advice below would be helpful.

My best advice would be to go to the library or autoparts store. They both would have a chilton or haynes manual for your truck. If you think you are going to work on it a bunch I would go a head and buy it, otherwise you should be able to check it out for a couple weeks.

Good luck and post up if you have questions.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

This will not work for a 2005 Trailblazer. The GMT360/370 ('02+ Trailblazer, Bravada, Rainier, Envoy, etc) had external fuel filters until the end of the '04 production run. For 2005 and further, the fuel filter was moved to inside the tank and is not servicable. The filter should not need to be replaced.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Anyone mind telling me where the fuel pump relay is on a first gen? Or how to depressurize it?

Thanks

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Anyone know the location of the fuel pump relay in a 97 bravada, they dont have the main fuse panel under the hood. They have a fuse panel when you open the drivers door andI have found a group of 4 relays in the glove compartment, one I know is the headlightsdue to its size. I suspect one of the other 3 is the fuel pump but Iwanted to check if anyone here knows before I go pullingthem one ata time to tell.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

The relay should still be under the hood somewhere. I am not entirely sure where it is as I have a 98. It should be a relay though and not a fuse and it should look similar to the one circled above. Post up a picture of your engine compartment and we might be able to find it for you that way.

Otherwise the other way to depressurize the system is listed above in the how to post. All you have to do is:

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

On a '97, the fuel pump relay will be located behind the glove box. It is the one closest to the driver's side.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Ok so this is a paint scetch with proportional sizes of the relays in the glove box, Is it the one I circled the largest or the closest to the driver side of the three that are alike?
http://img247.imageshack.us/img247/4200/13293066wk2.jpg

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Probably not the large one. That is probably the flasher module. The fuel pump relay would be the next one to the right.

If you have 3 relays, you probably have fog lights.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Ok on my bravada I removed the gray thing that goes through the relays to hold them in, but it still wont come out is there anyother thing holding the relay in or is it just really snug? Also is it necessary to depressureize the system if it hasnt run for say a day before doing it?

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Relays are just really snug, just keep pulling on it. Yes it is nessecary to depressurize, since the fuel system is always pressurized as long as you have gas in it. If you don't want to take the fuel system relay out, just depresurize it on the fuel rail, by depressing the schrader valve up there, see the original write-up and it tells you how to depressurize the system in these 2 fashions. Good luck.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

where is the main fuse block located under the hood

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Might help if you state the year. Judging from your other post, you have a '95. I do not believe that the '95s had an underhood fuse block. If they did, it would be just behind the air box on the driver side of the engine compartment.

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

Looking to replace the fuel filter soon, are there are any other (possibly higher flowing) options other than AC Delco?

RE: Fuel Filter Replacement How-To-Write Up Discussion Thread
 

I think they're pretty much all the same...

You'd never notice a difference on the 4.3, anyway...

Also, a 5/8" wrench will work instead of a 16mm... I don't have a 16mm wrench... Most cheap sets don't come with them, because they're virtually the same as 5/8"

It's actually surprisingly easy to do, as long as your fittings aren't rusted/stuck...

To get the lines off the bracket, I found it easiest, once the fuel line is disconnected (which, btw, my truck STILL had pressure, even after stalling out with the fuel pump relay pulled), slowly twist it straight down, while holding on to the other three lines...

Or press down from above on the filter bracket... Just reach around the frame with your other hand, lol.

Didn't even have to jack it up, put it on blocks, or anything... Just crawled underneath.

Feels like I gained 20 HP! :Dlol.

I suggest someone may want to add this to the DIY.
Anytime you are replacing the fuel filter be sure to either not use a 110 volt shop light or if you do keep it far away from the filter area. If a drop of gasoline should drip or spray onto the bulb the bulb can explode and ignite the gasoline vapors. If even a small amount of gasoline has spilled you can have a big fire. :icon_hyper:

That applies to incandescent bulbs. Florescent and LED lights won't have this issue.

great write up lenny,
i used this the last time i changed mine.

Thanks Lenny I'm sure this will come in handy when I do mine in a couple weeks!!

I found that putting on the new filter was a snug fit, and it was super snug, was to let the bracket sit in some HOT water for a couple of minutes. The new filter slipped on a lot easier.

Just changed mine at 99k miles. Filter wasn't hard to remove. I had already done this on the Wife's Regal when we first got it so I was prepared for gas still being in the line even after removing the fuse and cranking it a couple of times. Everything went smoothly and there were definitely lots of particles in the old filter when I dropped the line into a catch can.

Thanks for the write-up. I used a little silicone spray on the bracket before sliding the filter back into it.

My last trip was 18.5 mpg, 100% highway (as compared to 21 mpg, 100% highway when I first got it) so we'll see how much the new filter helps. Of course, I also need new plugs and wires and wouldn't hurt to replace cap and rotor as well...

is a 16mm wrench the only thing that will fit on mine slips

I do not think they are metric. If they are tight you should use a flare nut wrench on the nuts and a good fitting open end wrench on the filter nut. Place the wrenches so you can squeeze them together to loosen the nut. It usually works better and can save some skinned knuckles. A flare nut wrench is a 6-point box end wrench that has a notch missing so it will just barely fit over the fuel line. It gives the most grip to avoid rounding off the nut. If you do round off the nut you have to resort to vice grips.:icon_doh:

whet a little different but worked
 

The fitting was stuck but i got the filter cranked on by rotating the filter on to it till tight, looks good , no leaks. I geuss that worked :icon_wink:

Cuz the front end of filter rotates freely while clipped.

easiest my ass, this has been a pain

It's so easy a caveman can do it.