Fuel Filter Replacement

Last updated: June 17, 2000

Date: Wed, 16 Jun 1999 13:18:38 -0700
From: Max Cooper (m_cooper@csi.com)

The fuel filter is the same as the Miata, so it should be in stock at the dealer at least.

Ed.'s note: someone else mentioned that you need to use the old bracket from the RX-7 filter; see below.


Date: Sun, 9 Nov 1997 10:19:47 -0600 From: "O'Dell, Mark"

I just changed my fuel filter - having read some of the posts by folks on how to do this, I was expecting it to be very difficult. Quite frankly it was downright simple, if you follow a simple trick. Here is what I found.

The replacement fuel filter comes with the bracket to mount it to the car. The bracket is two pieces - one part bolts to the car, and the other encircles the filter. The job becomes easy if you separate the two pieces (they just bolt together). This way you reuse the piece that's directly bolted to the car. Then all you have to do is remove the two horizontal bolts on the existing fuel filter bracket (the bolts that hold the existing brackets together). These two bolts are horizontal and can be accessed using a ratchet with just a short extension.

The trick to this is that it turns out there is enough of a gap *above* the rear crossmember to get to those bolts from the back side of the crossmember. This makes unbolting the fuel filter a snap! In fact, it can be done in just a few seconds this way. The hardest part of all this was removing and detaching the fuel lines.


Date: Thu, 10 Jul 1997 17:25:31 -0400 (EDT)
From: mike curtis

I just changed my fuel filter last weekend. It was a big pain in the a@@, that would have been made easier if I had any tips before hand. So, since the list has been so great to me I will finally give something back. If anyone has any additions/or further tips please add them. This is to help everybody out!

Here are my personal tips:

Put the car up on some type of lift, I used some regular car ramps. The important thing is to get the back end up; there isn't much room under the car.

Next, the fuel filter is hard to find. If you are under the car with you legs pointing to the back the filter will be directly in front of the rear differental at the very top of the bottom of the car.

You are going to have the remove the silver aluminum cover that is behind where the passenger sits. It is held on by about 5 or 6 bolts. I first removed the fuel hose from the passenger side and stuck a bolt in the hole. A small amount of gas will come out.

Now, the bolt holding the filter on the passenger side can just barelly be reached with a 10 MM socket in a long extention. The bolt on the other side is a real pain in the ass. You will need the smallest 10 MM wrench you can find. I had to insert the wrench over a bracket (from the back of the car) and then it just barelly reaches the bolt. Once it is on the bolt you can turn it about 1/16 of the way around. It takes many turns and a long time to get the bolt off.

When the filter is loose, you can jiggle it around so that you can loosen the hose on the passanger side. Now plug the host with another bolt. Now, here comes the gas! Gas will pour out of the filter when you take it out of its "place". Just turn you head, close your eyes and put a nasty shirt on.

Putting the new filter in is "easy", just repeat the procedure in reverse.


Date: Mon, 06 Oct 1997 22:20:48 -0400
From: Grant Moyer

Couple quick additions:

- -Unscrew the gas cap, it should help relieve some pressure so not as much fuel gets pushed out

- -Tie a rag around your elbow or wear two sweatshirts before pulling the fuel lines, that gas really does burn the arm pit

- -Pull the line in the center of the fuel filter first and plug or clamp it quickly

Drew wrote:

> >>>Fuel Filter Replacement Instructions<<<<<
> For those of you who don't know: The fuel filter is mounted
> directly above the differential. I had to look twice and
> verify with the manual to make sure that I actally found it...
> almost completely hidden. Most of the work has to
> be done by feel. Took me a little over two hours.
> Things I have learned:
> -Wear goggles (I didn't and paid for it) and
> gas hurts when it gets in your armpits...aaahhhh!)
> -Have a 10mm socket w/3" extention, rags and if you
> don't want to reuse the factory clamps...get a pair
> 1/2" hose clamps. Wide mouth pliers.
> -While engine running...pull fuel pump fuse (leave out!)
> -Jack up car and put jack stands up! (VERY IMPORTANT)
> -Take 10mm socket w/3" extension and thru the rear
> crossmember (?) behind the diff. you can get to the two
> bolts holding the filter bracket.
> -Using wide mouth pliers move the hose clamps back
> about 2" from the filter.
> -When absolutly sure you have the clamps off the filter
> barbs (if you have not donned your goggles...do so now)
>  and remove hoses. Gas will go everywhere!!!!!!
> - I noticed that gas will continually leak out...I stuffed
> a bolt in it to keep it to a minimum...while I put the
> new filter in the bracket.
> -Put hoses on and secure clamps on filter...easier if
> not mounted.
> -Remount filter bracket to frame.
> -Replace fuel pump fuse
> -In engine diagnosis connector: jump the F/P and GND
> terminals with key in ON position. Maintain for 10 seconds...
> -Run engine...check for leaks....
> -Go take a shower
> Drew
> Yellow R1


Date: Sat, 15 Nov 1997 06:48:00 -0600
From: Martin Crane

... fuel filter replacement link, and I'll enclose a copy of the proceedure I've sent out to others. It was a joint effort, but I can't remember the other list member's name right now.

To release fuel pressure, as copied from workshop manual p. F-95:

  1. Start the engine
  2. Remove the circut-open relay.
  3. After engine stalls, turn off the ignition switch.
  4. Install the circut-open relay.

The circut-open relay is located in the small fuse panel beside the battery. The lid of the panel is labeled. If the writing is worn off, it is the large relay located on the outboard, forward side of the panel. There are only two relays in this line, and a series of small fuses running side to side by the cover hinge. My relay was green.

Next remove the heat shield from the underside rear of the car.

I removed both. It's helpful to remove both of the rear suspension splash pans --makes it easier to lay under the differential and bring boths hands into play at once.

Next remove the mount bolts holding the fuel filter mount plate to the car.

I removed the clamps first, because they were a pain and I decided that it would be easier to pull them with the filter mounted, not wobbling while I'm trying to pry the clamps off.

Most crucial tool in the whole process is the correct pair of pliers to remove the factory squeeze clamp on the inlet hose (the one in the center of the filter top). Most pliers are too long and run afoul of the other hoses in the extremely limited space you have available. I wound up using a very short pair of needle nose Vise-Grips after trying and discarding four other pliers (I have a very large toolbox). They worked because they had long, flat jaws; they would lock closed; and they were short enough to maneuver in the small space above the differential.

I then pulled the mount bolts, and worked the filter into a position so I could remove the hoses.

First thing to do is carefully grip the hose with a pair of pliers, (see above)and rotate it to break it free from the filter. Try not to slip and damage the hose, or grip too tightly and crush the fuel pipe on the filter. Once they are free, pull them off, and be aware, you will spill fuel. Protect your eyes and skin accordingly. Then remove the clamps holding the filter to the mount and prepare to reinstall.

One thing that will make things easier for you is to put a light coat of vaseline on the new fuel filter where the rubber hoses make contact. This will not harm the fuel system and should make both the installation and future removal much easier.
(Editor's note: I believe Vaseline will weaken rubber - at least you are not supposed to use it with condoms, which are latex - maybe the same holds true for rubber? Either way, I would recommend either silicone lube or grease, I would not think those would affect the fuel system, but you may want to confirm. --Steve)

I would urge anyone doing this job to substitute a worm drive clamp for the factory pinch clamp on the inlet hose (described above). Reason: you can get a nut-driver on the hose clamp screw BLIND and have it off in 60 seconds max as opposed to at least 60 minutes with the factory clamp.

Once the filter installation is completed, prime the fuel system to avoid excessive cranking when first starting the engine.

  1. Connect the diagnosis connector terminals F/P and GND with a jumper wire
  2. Turn the ignition switch on for approximately 10 seconds and check for fuel leaks.
  3. Turn the ignition switch off, and remove the jumper wire.

The diagnostic block is beside the battery and very close to the fuse panel holding the circut-open relay. It is labeled. The diagnostic block looks like it's separated into two halves: the outboard half containing three rows of connections, and the inboard half, containing two rows. Inboard refers to the center of the engine, outboard refers to the drivers side quarter panel.

The two terminals for the jumper wire are in the inboard half of the connector, on the only complete row. Connect the second and fourth connectors together with a wire. These are counted from the one at the nose of the car being the first, to the one nearest the windshield being the sixth.

Attempt to draw diagnostic connector as follows:

    o  o        o  o 
    o  x  o  x  o  o 

    o  o  o  o  o  o 
  o  o  o  o  o  o  o 
      o  o     o  o 

This is what it should look like, if your standing at the drivers front wheel, looking at he diagnostic block The X's indicate the location of the terminals for the jumper wire used to short the fuel pump and prime the system.

One last thing you may have figured out: jack stands or a pit are required. The job is not impossible, just a pain because of it's location.


Date: Mon, 26 Oct 1998 21:53:06 -0500
From: Charles_Crutchfield/CAM/Lotus@lotus.com

I replaced the fuel filter in my R1 on Saturday. I think it was engineered by the Marquis de Sade.

If you haven't already tried this one, and aren't an octopus, then you are in for a surprisingly difficult job when the time comes.

The problem is that, unless you are keen to remove the differential and all the attched parts, the fuel filter is remarkably difficult to SEE, much less reach. It sits directly above the diff and can only be gotten at with both hands by hugging the diff itself. Since it is connected to the fuel lines using spring clamps, you have to use both hands and often work blind....

It's a pain.

So here's how I did it (thanks to the various lists and FAQs that helped!):

Tools and Materials:

 - Safety goggles (wear these the whole time you are under the car)
 - Work light
 - Small Ratchet
 - 3" extension
 - 10mm socket
 - Small pair of pliers
 - Inch/pound torque wrench
 - Two center punches
 - Two half-inch worm-gear hose clamps
 - Dish soap


  1. To depressurize the fuel system, start the car and remove the green "circut-open relay" (located in the small fuse panel beside the battery) to cut off fuel flow. The engine will stall. Turn off the key. I also opened the gas cap to depressurize the tank.

  2. Raise the rear of the car as high as possible. I used a floor jack to lift it at the diff, put a jack stand under each side, and then removed the floor jack.

  3. Use a 10mm socket to remove the shielding on either side of the drive shaft, just forward of the rear axle. Most of these bolts are the same length, but one or two are shorter. I just made sure to remember which hole the short bolts go in, but you might want to write a note or mark the holes.

  4. Set up your work light to be able to shine up into the space above the diff. I used a great light that consists of a fluorescent bulb with one side shielded. It's not so bright that it blinds me when I look at it or so hot it burns me when I touch it. You can also stick it into places. I spent a lot of time with this sitting directly on my chest as I worked, lying on my back.

  5. Find the fuel filter (directly above the diff and right in front of a big, body-steel cross member that runs side to side like a wall between the gas tank area and the diff) and look and feel and probe all around it. Pay special attention to the fuel lines that run into and out of it. It is tight in there and you are going to have a lot to do. Think about how your hands and tools are going to fit and handle the pieces and parts.

  6. I used a small C-clamp to clamp the fuel line that runs out of the filter (the one that attaches to the bent pipe on the filter).

    NOTE ON CLAMPING FUEL LINES - I don't know how much clamping the line helped, and it was very hard to do, and fuel still came out. I also spent a lot of time trying to find a way to clamp the line from the fuel tank and was never successful. I even removed the shield from the leading edge of the tank (destroying a mounting point in the process) and wasn't able to find a decent length of clampable hose. I spent a lot of time worrying this problem. I didn't know how much fuel would be coming out of the lines once I took them off. Finally I said "Heck with it." In the end, as described below, I spilled some fuel and used center punches to stop the hose ends. There may be a better way, maybe with good hemostats.

  7. Use a 10mm socket, the small ratchet, and the 3" extension to remove the bolts that hold the filter in place. The bolts I chose to remove hold the two pieces of the mounting bracket together, not the ones that hold the bracket to the floor of the car. This looked easier to me, was recommended by the shop manual, and was recommended in a FAQ. You get at them by reaching _behind_ the cross member and through a small opening just below the floor. Put the assembled ratchet right up to the floor (the extension is now parallel to the axle) and then rotate it 90 degrees forward to get at the bolts (the extension is now parallel to the drive shaft). Remove the two bolts and the filter and its encircling bracket will come free.

  8. Use a small pair of pliers to loosen the hose clamps on the two fuel lines. Reach around both sides of the diff (hug it) to get your two hands on the fuel filter. It can move around a fair amount once the bracket is disconnected. It takes a while to get these loose and you will have to do some of it without being able to see.

  9. Get the two center punches and have them handy.

  10. Work the fuel hoses off of the filter pipes one at a time. It took me a fair amount of twisting to get them free. Work the last little bit off very slowly and carefully. Fuel will spill when it comes clear. Holding the end of the hose up seems to help a bit. Get the center punch into the hose end as quickly as possible.

  11. Pull the filter free of the car and get up to stretch your legs.

  12. Note the orientation of the filter in the encircling clamp and look at how you will put the new filter into the clamp. I tried to mount the filter with the clamp upside down (attached all the hoses and everything). It didn't work. I cursed with some vigor.

  13. Remove the clamp from the old filter and put it onto the new filter in the same orientation. Apply anti-sieze to the bolt. If you have a new clamp, feel free to use it. I didn't.

  14. Put a little dish soap on each of the pipes that comes out of the filter. This is a trick from an aircraft mechanic friend of mine. It makes it easier to mount and remove the hoses and won't hurt the fuel system.

  15. Break's over, get back under the car. Take the new filter, the new worm-gear hose clamps, and the appropriate tool for tightening them.

  16. Remove and discard the old hose clamps. Put the new clamps on the hose ends. I thought about reusing the original hose clamps, and even tried to do it. It was even harder to put them on than it was to get them off. After several minutes of cursing, I went with the new clamps.

  17. Fit the hoses and tighten the clamps. Orient them so that they'll be easy to get off next time.

  18. Using the torque wrench, re-attach the filter bracket, using anti-sieze on the bolts. The torque value for these is 69-75 in-lbf.

  19. Using the torque wrench, re-attach the shields, using anti-sieze on the bolts. The torque value for these is 69-95 in-lbf.

  20. Put the car down and go for a drive.


    Check out Brook's excellant page on this.

    Date: Tue, 27 Oct 1998 10:45:21 -0500
    From: Isaac Appleman

    I relocated my fuel filter to just next to my pre-cat. Haven't had a problem yet, though my friend keeps complaining about having to spray the floor board with the fire extinguisher every 10 minutes while riding with me.


    Date: Fri, 27 Feb 1998 19:44:57 -0600
    From: "Kevin T. Wyum" (aspi@winternet.com)

    > This fuel filter thing has been bugging me as it is about time to do mine.  I
    > went back to an old SX Performance catalog and they have what looks like a
    > great replacement for the factory fuel filter.  It is the SX Performance EFI &
    > Carbureted Indicating In-line Fuel Filter.  Part of the John Lingenfelter
    > signature series (ohhhhh, pay extra for that).  Part# is 41001.
    > They claim it will flow the max that a -10AN line can handle, up to 2000 HP.
    > Less than .15 PSI drop at 200 GPH.
    > >Quick and easy to install and remove with choice of 10 micron disposable paper
    > or 60 micron reusable stainless steel filter elements<
    > And a pop-up indicating sensor that warns when replacement or cleaning is
    > recommended.
    > It looks like a pretty slick unit.  All Mil-Spec anodized 6061 aluminum.  I can
    > scan in and e-mail the info I've got if anybody wants it.  What I wanna know
    > is......has anybody seen or used one of these before and what do you think?
    > How much did it cost?
    > Oh yea, the dealer that I got this from was ALATEC Racing Group.  314-639-1300
    > or 1-800-541-2345.

    I use one in my fuel system. Actually two of them. I have a smaller diameter one with the metal screen as a prefilter to keep the pump happy, then an SX pump and then the big one you're talking about using a paper filter. It's all bolted to an aluminum plate and mounted to the back of the subframe just behind the differential and in front of the fuel tank. Perfect amount of space. Very nice piece though. Think I paid $60 or so for it with the paper. Should be pictures of it on Kevin Tan or Trev's website.

    Date: Fri, 12 Jun 1998 20:45:34 -0400 (EDT)
    From: Stephen J Lee (Stephen.Lee@jhu.edu)

    With all this talk about fuel spilling everywhere when changing the filter, how about clamping the hose with, well, clamps?:-) If you know a doctor, or are a doctor, you can get those scissor-like clamps (I forgot what they're called) with the rubber tubing on the "blades". They lock shut so you can just clamp them on to your fuel lines and presto, no fuel shower. No messing with fuel pump fuses or emptying your tank.

    From: Jay Joe
    Date: Jan 14, 1999

    JayZ Fuel Filter Replacement Tips for the 3rd Gen RX-7

    Thanks to all those on the list and some great 7 net sites, I was able to do the fuel filter change in about 1 hour.

    In ADDITION to the net advice out there...here are some of my own that will let you do the change simply and quickly:

    1. Make sure you are in a well-ventilated place!!! CRUCIAL! Wait for a nice sunny day and do the job outdoors. I did it in my garage and just about passed out from the fumes. I think I'm still a little high....

    2. I used a Miata filter because the RX-7 specific filter is a special order item and takes awhile to receive, and it costs more. They are NOT identical but the actual filter itself appears to be the same. The piping on the Miata filter is a tad different on the intake side, but presents no major problems. Just transfer the mounting bracket from the old filter and reuse it on the Miata one (the Miata filters don't come with brackets...or at least the Canadian Tire ones don't).

    3. Get the lid off two Bic pens and use it to plug the fuel lines. This little trick works great, and will help save you from spilling too much fuel. If you have access to chem lab equipment, find two screw driven hose clamps. This will let you do the change with very little fuel spillage. Keep a towel handy!!

    4. It only took me a few seconds to get the filter dismounted by removing the two bolts that hold the filter bracket to the mounting bracket that attaches to the chassis. This way the piece that is already bolted to the car stays there. It is a real pain to try and remove the filter by trying to get to those bolts...the one on the intake side is almost impossible to work with. Do it the other way by removing the bolts that hold the filter bracket to the mounting bracket. Use a small extender and 10mm socket and you can get easy access just above the rear cross member.

    5. Dislodge the filter bracket first, and then use some small pliers to move the hose clamps. With the filter dismounted you can twist it this way and that to get the hoses off. Then simply twist and pull the hoses off...and voila!

    6. Put the new filter in, move hoses clamps back into position, remount, and that's it! It's not as bad as it sounds with the right advice. Using these tips it should only take 1-2 hours. Maybe 3-4 hours if you neglect step 1 and pass out somewhere in between.

    As big of a pain as this sounds like, I think Isaac and a few others had the right idea - relocate the filter when you do this the first time.

    As Kevin mentioned above, get an aftermarket filter that is re-usable too. (Or at least cheaper, easier to find in stores, and easier to change than the stock filter.) I don't know if Canton makes fuel filters (I seem to remember Carlos Iglesias or someone saying that they do - I know Carlos has their oil filter), but they make very good re-usable filters. --Steve

    Date: Sat, 10 Apr 1999 00:15:54 -0500
    From: Dale Clark (dclark@networktel.net)

    Well, I've just done 2 3rd gen fuel filter jobs in the last week. After all the moaning/griping about the job I've heard, it's MUCH easier than I thought. The 2nd time I did it it took all of 30 minutes.

    Here's my tricks -

    1. Remove the circuit opening relay. Pop open the fuse and relay box on the driver's side shock tower under the hood. With the car running, remove the big green relay. I had to use channel locks to get a good grip. After you pop it out, the engine will stall after about 3-4 seconds. This depressurizes the fuel system.

    2. Jack up the rear passenger side of the car. There's a metal plate on the passenger side just forward of the differential - remove it, it's held on with a number of 10mm bolts. Now, it should be pretty easy to see the fuel filter - it's above the differential.

    3. Get a short pair of wide-nose pliers. If you're laying under the passenger side of the car with your feet sticking out the back, snake your hand up on the driver's side of the differential. You can get your hand up where the fuel filter is. Get the pliers on the hose clamps that hold the rubber fuel lines onto the filter itself and move them back on the hose so they're not clamping the rubber line onto the filter.

    4. Get a shop rag handy. Pull the rubber fuel line off the driver's side of the filter. Some gas will come out - be ready to move your hand away quickly. If you do it right, you should get some gas on your arm, but not much. Mop up the excess fuel. Then, pull the hose on the passenger side off - very little fuel should come out there, if any.

    5. Get a 10mm socket, a short (3 inch long or so) extension, and a socket wrench. If you look at the filter, you can see the bracket that holds it on has 2 10mm bolts securing it to the frame just beneath the filter. If you come at the bolts from the backside of the car, it's a perfect fit with the short extension. Just reach up behind the frame that's aft of the differential and you can get on 'em very easily. Break both loose, give 'em a couple of turns, then remove the socket wrench and turn them the rest of the way out with the extension and socket only - much faster.

    6. With the 2 bolts out, remove the filter. There's 1 10mm bolt that tensions the bracket onto the filter. Remove the bolt and transfer the bracket to the new filter, paying attention to the placement of the bracket. Just put it on the new one in the same orientation it came off of the old filter.

    7. Reassemble. This goes by pretty easily. Just make sure to push the rubber hoses on all the way, and move the clamps back into the same position they were originally - that being fully on the metal tube on the filter.

    8. With everything back together, replace the green relay. You can jump 2 of the connectors to prime the fuel system - Brooks' page outlines the technique. I just cranked the car until it started :). About 7 secs of cranking, stop, then 2-3 more secs and the engine will crank. Drive the car around the block nice and easy, then check for leaks.

    Hope this helps somebody out - there definitely shouldn't be as much fear about changing the fuel filter as I've seen on the list. Actually, I'd say it's about as hard as changing the filter on a 2nd gen - some things are easier, some harder.

    Date: Fri, 16 Jun 2000 09:01:07 -0700
    From: "Hoskinson, Jeff" (jjhoskin@pscnet.com)

    To those of you that haven't CHANGE YOUR FUEL FILTER, especially before doing ANY mods.

    This is my second fuel filter replacement and I think that I learned a few things from my first mistakes....

    1. Run car nearly dry on fuel.

      This came from a "note to self" after changing the first filter with nearly a full tank and having fuel constantly running out of the hose on my chest and down my arm.

    2. Remove the yellow relay in fuse box under the hood while the vehicle is running, when it quits shut the car off and replace it. Channel locks make it easier to remove, don't crush it though.

    3. Jack the rear of the car up as high as you can get it, use jack stands...

    4. Remove both shields under the rear axles.

    5. Using a 3/8 drive ratchet with 2" (?) extension and 10mm socket remove the two bolts holding the filter bracket to its mounts from the REAR of the rear subframe. There is a space large enough between the rear subframe and the fuel tank to get the ratchet in there. This removes the filter AND the bracket.

    6. Using some pliers remove the little spring clamps to the inlet and outlet hoses, remove BOTH the spring clamps before you remove the hoses. It is probably easier to put your arms around the diff, I pushed the filter over towards the passenger side of the car and I could see pretty well.

    7. Pull and twist on the hoses, get one loose and then try to get the other loose, resist the temptation to get some pliers on the hose, the "teeth" of the pliers might cut the hose, I don't think anyone wants to try replacing those hoses if they can help it. I pulled and twisted and both the lines broke free. Once both the hoses are loose then remove them, this minimizes the time that gas (and resulting fumes) will be around.
    8. Put it all back together....

    It took me about 20-30 min to change the filter, just a note, if the filter has a silver label on it then it is the original filter...

    Spencer Hutchings replaced and relocated his fuel filter with an SX unit. See the Fuel Pressure Regulator page for pictures and some notes.

    [Mail me] [To Lightning home] [To my home page] [Copyright Notice]