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2004 non_gmt360 other
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Discussion Starter #1 (Edited)
GM recomends the fuel filter be replaced every 30,000 miles.

NOTE: This procedure is for the 2002-2004 4.2L I6 motor without a tank shield and was done on a Trailblazer (Envoys should be the same. I know the 2004 Envoy has the same part number).

**The fuel filter is located directly in front of the gas tank on the drivers side.

Tools:

- Philips head screwdriver
- Needle Nose pliers (can be done without them but they make it easier. See pic)
- A pan to catch gasoline when removing the connectors (oil pan will do)
- A jack
- Safety glasses

Materials:

- A fuel filter (part # FF864 at Autozone)
- Shop rags


Step 1) Remove gas fill cap

Step 2) Remove the fuel pump relay in the under hood fuse box. Then start the engine and run it till it stalls. Continue to crank it for 5-10 seconds after.

Step 3) Disconnect the negative battery cable.

Step 4) Jack up the front drivers side of your trailvoy (if necessary)

Step 5) Locate the fuel filter directly in front of the fuel tank. Clean the area around the inlet and outlet fittings (better than I did) making note of the order of the two (the fuel filter is directional).

Step 6) Put the pan underneath the filter. Unscrew the cap off the bleeder valve and depress with the pliers or screwdriver to release any possible remaining pressure then screw the cap back on.

Step 7) Use the needle nose pliers (or your fingers) to squeeze the quick connect clips and pull off each of the hose fittings one at a time noting the location of the inlet and outlet tubes. The filter is directional. (some fuel will come out when disconnected).

Step 8) Unscrew the filter clamp and remove old filter. (the filter will have more fuel in it. Tilt it into the pan to spill the excess out)

Step 9) Screw in the new filter (inlet side towards the tank, outlet towards the engine), snap the fittings back on, lower your trailvoy, replace the relay and negative battery cable, screw on your gas cap.

Step 10) Start it up. (it may take a few cranks to get the fuel back up).
 

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2002 chevy trailblazer_lt_ext
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326 Posts
Very nice write up, and nicely done on the pictures...this on my long list of to-do's lol
 

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2004 chevy trailblazer_ls
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3,329 Posts
I just did this on mine yesterday... I did not disconnect the fuel pump relay though. Once you release the pressure with the valve, the same amount of fuel is going to come out of the filter/lines regardless of having the pump relay in and not letting the engine die... I think I spilled maybe 1-2 ounces of fuel...

My original filter had 75k on it... maybe that was part of the reasoning behind my craptastic mileage. Let's see how she does now... LOL

Awesome write up and great pics though... Submit the Write Up with pics for an Article...
 

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2004 chevy trailblazer_ls
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I did this on my Trailblazer about 400 miles ago and have seen a jump in gas mileage of around 1 to 2 MPGs. This is definitely worth the time and small amount of money!
 

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2004 non_gmt360 other
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Discussion Starter #7
I just did this on mine yesterday... I did not disconnect the fuel pump relay though. Once you release the pressure with the valve, the same amount of fuel is going to come out of the filter/lines regardless of having the pump relay in and not letting the engine die... I think I spilled maybe 1-2 ounces of fuel...

My original filter had 75k on it... maybe that was part of the reasoning behind my craptastic mileage. Let's see how she does now... LOL

Awesome write up and great pics though... Submit the Write Up with pics for an Article...
Thanks. Just being over protective with the relay. 75K? :dielaugh: I felt bad that I left it go for almost 5K over. Boy, was I being hard on myself :bonk:

That was my 1st fuel filt change on this (the factory sticker on the old filter is a giveaway). My 2004 with less than 35000 miles on her. Haven't ran a full tank of fuel since the change so I can't say if it helps fuel economy but I did run a lucas fuel system cleaner in the tank before the change hoping to knock any barnacles loose in the system.

I am working on getting this over to the article section, thanks. I've gotten alot from this site. Just wanna give some back.
 

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2004 non_gmt360 other
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Discussion Starter #8
I did this on my Trailblazer about 400 miles ago and have seen a jump in gas mileage of around 1 to 2 MPGs. This is definitely worth the time and small amount of money!
Welcome to the forum.

1 to 2 MPG huh? :undecided Looks like i've got something to look foward to :woot:.

The total cost (filter) was less than $20
 

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2004 non_gmt360 other
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Discussion Starter #10
Good Job on the write up.


Really good idea pulling the fuel pump relay!! i just clamped both of the hoses that lead into it then pulled it off, but thats much better !!
:thx

I like your floorboard LED how-to. Future mod now.
 

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2003 chevy trailblazer_ls
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5,268 Posts
thats how I do my filter change.
Also remove the relay.
 

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2002 chevy trailblazer_ls
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I am WAY overdue on doing this!! This is a great write up!! Going to have to do this either today or in the next few days!!

:thx
 

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2004 non_gmt360 other
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Discussion Starter #16 (Edited)
:thx
I'm suprised nobody caught my small photographical error :x. I realized what I did after I was finished but it was too late to take a different pic.

In the 6th picture the fuel is draining with the connectors off. In the 7th pic with the screwdriver, the quick disconnects are back on the filter for no reason. :bonk: It must have ben the gas fumes. . . :drool . Just want to say to the first timer that theres no need to put the connectors back on to unscrew the filter clamp. :duh:.

Snaping the connectors back on wont hurt anything. Just not necessary.

I'm glad the point still gets across. . .:D.
 

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2002 chevy trailblazer_lt_ext
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I just got done crawling under my TB and noticed it has the factory fuel filter still on it and I just turned 91,xxx miles!!!! And, to top it all off, the strap to hold the fuel filter in, isnt attached to anything, its just hangin there!! Glad I decided to go ahead and buy a new filter
 

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2003 chevy trailblazer_ls
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91,000 and still the factory filter. dang....
 

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2004 non_gmt360 other
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Discussion Starter #19
I just got done crawling under my TB and noticed it has the factory fuel filter still on it and I just turned 91,xxx miles!!!! And, to top it all off, the strap to hold the fuel filter in, isnt attached to anything, its just hangin there!! Glad I decided to go ahead and buy a new filter
May also have been replaced with another GM filter. Not the original owner i'm guessing ? I'm not either. I'm the second owner. I bought it with almost 28000 miles on the clock so i'm sure this was the first filter change.

The rust was a dead giveaway. :yes:
 

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2002 chevy trailblazer_lt_ext
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May also have been replaced with another GM filter. Not the original owner i'm guessing ? I'm not either. I'm the second owner. I bought it with almost 28000 miles on the clock so i'm sure this was the first filter change.

The rust was a dead giveaway. :yes:
Yeap, I am the second owner of it, so there is a good chance it has been changed before
 
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