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  1. #1
    ScorLibran
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    How to replace the fuel injectors on your E36 M3

    These are the instructions I could not find anywhere on the internet! I recently installed a set of Bosch 24lb'ers on my '95, and I had to do it (as nerve-racking as it was) by trial and error. So after having to back up and redo a couple of steps, here is my final outcome concerning instructions for anyone wanting to replace/upgrade the injectors on their E36. BTW...these instructions only cover the 3.0 liter engine...I don't know how many differences there are between the 3.0L OBD I and the 3.2L OBD II.

    These instructions assume little or no hands-on familiarity with the 3.0 liter E36 M3 engine, so if you know your way around under your hood, forgive my occassional over explanations. And if anyone sees anything wrong with these steps, please respond so we can all know the right way to do it.

    Also, I'm in LA right now, 3000 miles away from my car (sniffle, sniffle), so I'm writing this from memory, but I wanted to get it submitted before I forgot most of what I did.

    NOTE: If you are installing 24lb injectors, make sure your ECM chip can properly control the injectors at this pressure. Jim Conforti programmed the one I use, and it works beautifully. There may be other brands as well. If you are installing stock 18 lb'ers, any E36 chip will work, factory or otherwise.

    Tools needed: 10mm socket and ratchet (either 1/4 or 3/8 drive is fine), 15mm socket (or possibly 13mm, have both just in case), pocket-sized flat head screwdriver, flashlight to see what the hell you're doing in the shadows under the injector rail (the one from your glovebox will work) and needlenose pliers.

    1. Right down the middle of the top of the engine (longitudinally) is a black plastic cover over the fuel rail/injectors (NOT the one that says "BMW M Power", but the one next to it). Use a flat-head screwdriver to pop the two bolt covers and then use a 10mm socket and ratchet to remove the bolts under them.

    2. Lift and remove the plastic cover to expose the fuel rail.

    3. Remove the two bolts (again, 10mm) connecting the fuel rail (on the right side as you stand in front of the car) from the injector electrical rail (on the left side, about an inch apart from the fuel rail).

    4. Remove the two 10mm nuts holding down the electrical rail on the left side. Here's the first mistake I made...I removed the black cover on this component to expose the wires which feed electrical power to the injectors. THERE IS NO NEED TO DO THIS, so leave the electrical rail intact!

    5. Remove the ground wire coming from the electrical rail going to the water pump (I think) mount on the top-front edge of the engine. I think this was a 15mm bolt (or was it 13mm?).

    6. There is a metal clip holding each electrical connector under the electrical rail to the electrical plug on each injector. Use a pocket flat-head screwdriver to pop the sides of each clip to the side to release the connector from each injector. Do this front-to-back, and as you unclip each one, lift the electrical rail from the front to unplug each injector's electrical connection. You will be slightly bending the electrical rail, but the whole thing is basically a long plastic box, so if you're gentle you won't break anything. NOTE: Make sure you the clips don't come completely off each connector, because they will fly God-knows-where! Just move the sides of each connector apart and let the corner of the plug hold them as you unplug them from each injector.

    7. Once you have all electrical connections removed from all injectors, remove the two 10mm bolts holding down the fuel rail (on the right side). NOTE: There is no need to remove the fuel lines at each end of the fuel rail, as there should be just enough slack to move the rail the short amount needed...there was on mine.

    8. Lift the fuel rail gently but firmly to pull each injector out of the manifold. The only tension you'll feel will be the O-rings at the base of each injector. Some may be stiffer than others, so take your time to work them loose.

    9. The second-hardest part I encountered...Under the fuel rail there is a brass clip holding each fuel port from the rail to the top of each injector. Use your flat-head pocket screwdriver to loosen each and use your fingers or (gently) needlenose pliers to remove them. These are just in a difficult place, and be careful not to let these parts go flying! I was told by my dealership service dept that these are not kept in stock, so if you lose one or more, your baby will be sitting for a week or more while you wait to get some shipped to you. For each clip you remove, pull the injector from under the fuel rail. Again, the only resistance will be O-rings, so work each one out gently.

    10. Once you have all your old injectors lined up on an oil rag next to your shock tower (that's where mine ended up), pop the plastic covers off the ends of one of your new injectors.

    11. Insert the new injector into the front port under the fuel rail. Here's something I ran into: I couldn't get one injector to insert all the way into the rail, and soon discovered that an O-ring had come off of one of my old injectors and was taking up permanent residence in my fuel rail (discovered by feeling inside the fuel rail port with my little finger). I used my pocket screwdriver to remove it, and the new injector popped right into place. Once you have the injector inserted, replace the brass clip. Replacing the clips just the right way was the hardest part for me.

    12. Repeat steps 10 and 11 until you have seated all injectors into the fuel rail.

    13. Holding the fuel rail over the manifold, carefully insert the bottom end of each injector into the manifold port. It will seem like like you need seven hands to do this (one for each injector and one for the rail), but with patience and a little dexterity this won't be too difficult to do.

    14. Once you have seated all injectors in the manifold, replace the two 10mm bolts holding down the fuel rail. (I can't remember if the electrical rail needed to be bolted down first, so if you see that this is the case, skip this part and bolt down the fuel rail after bolting down the electrical rail later).

    15. Again, using seven hands ;) line up and plug in each electrical connector from the electrical rail to each fuel injector. When the electrical connections are in place, make sure each clip on each connector is popped back over the connector to prevent the connections from coming loose later. Face it...it would not be good to lose an injector connection at highway speed...it would feel just like losing a cylinder.

    16. After reconnecting and re-clipping each electrical plug, replace the bolts holding down the electrical rail (and the fuel rail if not already done).

    17. Final check before replacing the long plastic cover...CRITICALLY IMPORTANT: Make sure you have a seated each injector into the fuel rail and into the manifold well, and that each brass clip was replaced and snapped into place solidly. If an injector is not seated properly, it will spew fuel and will at least make a mess and waste fuel, and at worst BURN UP YOUR CAR AND POSSIBLY YOU ALONG WITH IT!!! Use a rag to dry any fuel which may have collected around and under the fuel rail assembly when you took it apart.

    18. If you are installing a new ECM chip, do it now (if not done already).

    19. Before replacing the plastic cover on the top of the engine, start the car and check THOROUGHLY for any fuel leaks or bad connections at the fuel rail or electrical rail. NOTE: When you first start the car, it will start with some difficulty and will sputter a little when it does start. THIS IS NORMAL. When you took apart the fuel rail assembly, a little gas was sure to spill out and leave a bit of an air pocket in the fuel system. Once the system re-pressurizes with fuel, and assuming you have no leaks, your car will run smoothly after a few seconds.

    20. Turn off the car.

    21. If you see no fuel leaks, and more importantly, if you do not smell gas, replace the plastic cover on the top of the engine with the 10mm bolts, and pop the bolt covers back into place.

    22. Put away your tools, close the hood, and go for a drive. When you get back home, check under the hood again for any fuel leaks and for any fuel odor which might indicate a leak.

    I hope this helps anyone with an E36 M3 wanting to replace their fuel injectors themselves. Again, tell me if something in these instructions is wrong or missing.

    Happy Modding!
    ScorLibran


  2. #2
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    those brass clips are a Biatch aren't they?


  3. #3
    Scott Snider
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    Thanks...valuable stuff to know!


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    One missing step...

    On the fuel rail is what looks like a tire valve. As stated in the Bentley manual this is used to clear the fuel rail of fuel, attach a high pressure inflator and clear fuel before removing injectors. This will push the fuel back in to the gas tank. I did this last week and it make for less mess when removing the injectors.

    Mark

  5. #5
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    E36 shortcut

    Hi great article- I did what you said and I think I found a couple time savers- put a shop towel under the injectors once you pop them out. Helps sop up fuel when you i clip them from the rail and if you drop the clip. You don't have to purge the fuel or whatever just do what you said and a few drops will land on the shop towel.the biggest time saver I found was not to take off the brass clip all the way- just pry one side and gently pull till its out- then do the other- the brass clip should be the last thing to take off before the injector come out. I did one at a time finding it easy actually except for the far back one grr!!!
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    E36 short cut

    What I meant to say was do not remove the brass clip at any time- just pry one side then the other- when you put the injector back in it just clicks past the brass clip!!!
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