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  1. #1
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    "How-To" 2.5L Optimax Fuel, Direct Injector, and Fuel Rail removal/reinstallation

    Have seen many folks ask about this, so when I decided to remove my fuel system late August for cleaning, validating, and servicing, I decided to document the process. I created a draft in Word and have shared it with Don for his review/edit/comments prior to posting. The final product follows below and includes all of his comments and recommendations.

    Though mine is a 2.5L Optimax, the procedure should be similar for the 1.5L & 3L.

    To start, I recommend you have a bona fide, OEM Mercury Service Manual for your engine based on YOUR engine serial number before starting this procedure. I would NOT recommend attempting this without one, especially reassembly.

    Other than small wire cutters (work great for tie wraps), an autobody trim tool, known accurate lbs/ft torque wrench, either Oetiker pliers or a pair of end nippers, no other special tools required. You will need about a dozen radius head tie wraps and you’ll be provided with replacement Oetiker clamps after injector service is complete.

    I’ll dispense with the obvious items (remove upper and lower cowling, etc.) and get right into disassembly. Depressurize fuel and air systems via Schrader valves on fuel rails starting with the air side first. I noted this is not necessary if your engine has not been run for at least 8hrs. Mine sat overnight and there was no pressure on either side. Still, not a bad idea to remove the caps and confirm just in case.

    The first thing I did was identify the Oetiker clamps that needed to be cut and started with the one on the air compressor above the port fuel rail (green arrow in pic). The red arrows show the fuel injector connectors that need to be disconnected and the blue arrows show the direct injector (DI) connectors. Note: 3L direct injector connectors face IN versus OUT as on 2.5L models.

    portrail.jpg

    To remove the fuel injector connectors, simply depress the metal retaining clip from the back side like this…

    FIconnector.jpg

    The top and bottom side injector connectors are a tight fit between the metal brackets that surround them, but they will fit through, just be patient and careful. While still on the port rail, go ahead and remove the connectors on each DI (marked with blue arrows), a small screwdriver or right angle pick tool may be helpful in releasing connector retaining tabs. NOTE: Use caution to prevent breaking plastic retainer “ears”.

    Repeat the process for the starboard rail side and direct injectors.

    Now that the connectors have been removed, it’s time to move the injector harness out of the way. There are 4 “Christmas tree” style wiring harness retainers that need to be released from the brackets surrounding cylinders 2/6 and 1/5 side injectors. An auto body trim tool is helpful here and is what I used to detach these retainers from the brackets. Don says most later models have a tie-wrap style retainer like those used on used on my engine. There may have been other methods used on earlier engines.

    harnessclip.jpg

    Once these four retainers are freed from the brackets, you’ll need to disconnect both the water pressure and pitot sensor connectors (3 Liter models will have only water pressure on the coil plate).

    waterpressuresensor.jpg

    Snip the radius head tie wrap at the water inlet to the compressor and remove the hose. Don commented that 3L models vary…some have a hose entering the bottom of the port rail, and exiting the top of the port rail. Others may have only bare (white-nylon) fittings, which have no hoses connected to them.

    wateroutlet.jpg

    Then open the double hose retainer (left green arrow) and snip the radius head tie wrap on the back side of the compressor. Don added it is, “Very critical that the air-line be ATTACHED to the rails, and sent in with that assembly for service.”

    hoseretainers.jpg

    A small screwdriver (pocket type) is handy for releasing the “catch” of the double hose retainer.

    Once all these items have been completed, lift and move the injector harness out of the way.

    At this point, I followed the fuel hoses from the rails to their origin on the VST, in my case one port side and one starboard side. The port fuel line was easiest so I cut its Oetiker clamp first, then clamped the hose prior to removal to minimize fuel spill, and removed the hose from the nipple. Drain any fuel into a suitable container. Repeat for starboard fuel rail. WARNING: VST connections may differ on 1.5L and 3L Optimax engines.

    VSTconnections.jpg

    You may find a few other tie wraps on the hoses, I had one on the port hose below the VST and one around the pitot portion of the water pressure hose (not used in my application). Snip the corresponding radius head tie wraps as appropriate.

    You will need to remove the cooling lines from the strainer and the block, I had already removed the hose from the strainer in the following pic. Both are attached with radius head tie wraps. This would also be a great time to clean the strainer!

    coolantlines.jpg

    Now that all the lines, connectors, hoses, etc, have been removed, you are ready to remove the fuel rails. Remove the two nuts holding the fuel rails in place, then carefully slide the fuel rails off ensuring the direct injectors remain in the head (they should).

    portrailremoved.jpg

    Once both rails have been removed, place the entire assembly out of the way. I use this style of clamp for fuel lines…

    clamp.jpg

    A piece of plywood on a stand of some kind works well to allow rails/hoses to drain. My P/U box dolly makes a great portable work table…

    railshoses.jpg

    From there, I went about removing the DIs. Some were difficult, some came out easily. Best advice I can offer is be patient, rotate the DIs while pulling straight out and be prepared if one should suddenly release. Make sure you have a firm grip, as Don says, “dropping a DI can cost you a bundle.” Sort of goes without saying, but I don’t have any pictures of the removal process, not enough fingers.

    As you remove the DIs, mark their location (cyl 1, 2, etc.) on the bottom side of the connector (faces the head) with a Sharpie. Don will need to know which cylinder they came from. I bagged each DI and marked the bag as an extra measure. I sent reed blocks to Don at the same time so I could eliminate the OE stainless steel reeds and replace with TDR…

    directinjectorsreedblocks.jpg

    At this point, you are finished with disassembly. I drained the rails per Don’s instructions and left them to sit overnight. I repeated again next day and got more fuel out. I left the rails sit while packing the reeds and DIs, then got a few more drops out of the rails/hoses one more time before packing. Be sure to pack per instructions on Don’s website and Injector Service form. Pay particular attention to Don’s warning, “Bubble-wrap is recommended - DO NOT use polystyrene products, such as “Circus Peanuts”.

    In my case, I purchased two rolls of bubble wrap and double or triple wrapped everything. Small price to pay considering current replacement cost of all components I sent (including assembled reed blocks) is close to $5,000 (what I insured my package for)!

    Now is a great time to do annual maintenance while injectors are being cleaned and validated. Spark plug access is wide open with all the parts out of the way.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  2. Member
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    #2
    Reassembly is basically reverse of removal.

    IMPORTANT: Your work area, hands and tools must be CLEAN, and free of dust, dirt, grime and debris while the freshly serviced components are open, and while being installed.

    Since I also upgraded to TDR reeds at the same time, I started with installing reed blocks to the reed plate. An accurate inch pounds torque wrench is essential. Since I didn’t have one that covered the required torque range, I bit the bullet and bought a Computorq 3 (CDI 2401CI3) 1/4” torque wrench with a torque range of 24 – 240 inch pounds. Not cheap, but critical for precise torque readings during reassembly.

    Parts laid out ready for reassembly. Note the Mercury service manual open to respective page for reed block install.

    reeds.jpg

    Reed plate assembled and ready to attach to plenum.

    finished.jpg

    Don recommended a light coating of oil on the inside of the reeds prior to assembly. I had to get creative, so used a very small pump sprayer, with just enough Premium Plus oil for it to work. I placed the reed plate on blocks of wood to protect the cages, sprayed them with oil, and let the excess drain onto the paper. Plenum installed after coating the reeds. Green arrows point to excess oil.

    plenum.jpg

    Plenum installed.

    plenuminstalled.jpg

    Don marks the DIs on the bottom side of the electrical connector after cleaning and flow testing. Be sure to install in the correct location as marked.

    number.jpg

    Before installing the direct injectors, be sure to liberally coat the o-ring with oil. I used Premium Plus since my DFI oil is at the lake where we normally keep our boat. I was able to install all the DIs by hand with no problems.

    I had one bad DI that needed to be replaced. New DIs come with a neat metal cap that keep the Teflon seal properly compressed prior to installation. Instructions included with the new DI state to not leave the cap off for more than 60 seconds before install, so if you need to replace one or more DIs, do not remove the cap until you are ready to oil and install ASAP. I will tell you this, that cap is a bear to remove! Don shared this recommendation after I had figured out how to remove the cap,

    “A pair of needle-nose pliers (points held LOOSELY so as not to nick the o-ring) can be utilized to help pry the dust cap away from the injector body. Your needle-nose pliers should touch ONLY the metal dust cap and the metal portion of the injector body.”

    I used a pair of common pliers, opened to widest setting, and gripped the flattened rim at the bottom of the cap only, twisting slightly while pulling towards me. This worked well and didn’t require any contact with the DI. Be careful so you don't smack yourself in the mouth when the cap lets loose!

    cap.jpg

    From here out, the rest of the process is basically the opposite of removal. Don will install the side (fuel) injectors during the cleaning/flow testing/calibrating process fuel rails will be ready to install when returned.

    Be sure to torque all fasteners to proper specs per your service manual. Also, make sure to replace any removed radius head tie wraps with exact replacements – common tie wraps are not suitable substitutes.

    Buttoned up and ready for a trip to my mechanic for oil pump prime sequence!

    buttonedup.jpg

    A few final comments from Don:

    “Oil pump prime should be done on the (dealer) Computer Diagnostic System, or a DDT. Don’t try to “cheap out” with the “jockey-the-shifter” method you may read about on the internet- it will cost you far more that having the oil pump prime done correctly (double oil for the first 2 or more hours, and likely a complete set of spark plugs).”

    “One additional pointer: During (or after) the oil pump prime, it is helpful to relieve the AIR that is trapped on the fuel side of the system, from the FUEL Schrader valve. This helps to ensure liquid fuel to all of the fuel injectors (and the engine will fire off and run much more smoothly). If you skip this step… don’t worry, it will still start and run (just don’t be surprised by the rough-running condition for the first 15-30 seconds while air is purging through the injectors).”

    My mechanic performed the oil pump prime, provided a complete run history including and faults, reset counters, and ran the engine for 20mins to ensure no leaks and the reserve tank was fully purged of any air and only charged me an hour's labor (which I felt was very fair). Since he ran the engine, I didn't experience any rough running condition the first time I dunked the boat.

    I hope this helps anyone who plans to remove/install their DIs, injectors, rails, it really isn't that difficult. A BIG thanks to Don for reviewing my work prior to posting here (and right in the midst of his computer issues), very much appreciated.
    Last edited by SilverFox579; 11-01-2015 at 12:43 PM. Reason: Add some additional info
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #3
    Thanks, Phil.

    Adding this post to the 2.5L and 3L Forum F.A.Q. sections.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #4
    Quote Originally Posted by SilverFox579 View Post
    IMPORTANT: Your work area, hands and tools must be CLEAN, and free of dust, dirt, grime and debris while the freshly serviced components are open, and while being installed.
    Thoughts on the removal/re installation process if the only option is the boat sitting outside in a winter environment This seems fairly simple and something I could handle but I feel apprehensive about it. Unfortunately no one within a reasonable distance of my location that I know of does Injector service so it does not seem like I have any other options. If I could get a shop to do the removal would it be safe to tow the boat back home an hour afterwards with everything removed to sit outside in winter weather and then towed another hour back to the shop for re installation after the service is complete?

  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #5
    Suggest fogging engine BEFORE disassembly.

    Plug or cap any open fuel/air line connections.

    Apply duct tape (or otherwise plug) direct injector openings after disassembly.

    Follow those recommendations, it should be fine.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  6. Member CigarBasser's Avatar
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    #6
    Could you send the unit as pictured in pic "11" or do you have to breakdown further?

  7. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #7
    Quote Originally Posted by CigarBasser View Post
    Could you send the unit as pictured in pic "11" or do you have to breakdown further?
    On 2.5L Optimax Models, that picture is PRECISELY what the components should look like when sent in. Direct injectors should also be sent (individually wrapped in bubble wrap).



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #8
    If anyone has specific questions, I'd be happy to share my personal experience.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  9. Member Charger69's Avatar
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    #9
    I had read about having the TDR reeds and the validating on the injector system done and had felt a little intimidated about doing it myself. (I am an ASE Master tech)! Your writing about your experience has eased my worries somewhat. I appreciate your writing and comments on the job, I will be attempting this myself now, as soon as I order the correct manual for my engine. Again, thank you!

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    #10
    This thread helped me SOOO much when removing my rails and injectors. I dont know if I could have done it without this thread! Thanks SilverFox!
    99 ChampioN 181
    98 Mercury 150 Opitmax

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    #11
    I am happy to hear others have "empowered" themselves from my post. This is something most anyone can do with a few tools and an OEM factory service manual.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


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    #12
    Quote Originally Posted by SilverFox579 View Post
    I am happy to hear others have "empowered" themselves from my post. This is something most anyone can do with a few tools and an OEM factory service manual.
    I agree. I did this (with a little help from a friend) and reed replacement on my 150 Optimax. I had a Factory Manual and Don's help. I sent the Fuel Rail system to Don. The Optimax runs beautifully now.
    Mark it Zero!

  13. Member J Risco's Avatar
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    #13
    Quote Originally Posted by SilverFox579 View Post
    Now is a great time to do annual maintenance while injectors are being cleaned and validated. Spark plug access is wide open with all the parts out of the way.
    Quote Originally Posted by SilverFox579 View Post
    Buttoned up and ready for a trip to my mechanic for oil pump prime sequence!



    A few final comments from Don:

    “Oil pump prime should be done on the (dealer) Computer Diagnostic System, or a DDT. Don’t try to “cheap out” with the “jockey-the-shifter” method you may read about on the internet- it will cost you far more that having the oil pump prime done correctly (double oil for the first 2 or more hours, and likely a complete set of spark plugs).”
    Am I missing something here?

    First question, is an oil prime sequence and 2 hours of double oil required after an injector service?

    Second question, if it is required, why would you do plugs while reassembling, then have to do them again after 2 hours when you are done with double oil?
    2021 Phoenix 920 Elite / SHO 250
    Bullet 21XD / 250 XB (Gone to a great home in LA)
    "There is no such thing as a bad day fishing!"

  14. Member J Risco's Avatar
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    #14
    sorry, double post
    2021 Phoenix 920 Elite / SHO 250
    Bullet 21XD / 250 XB (Gone to a great home in LA)
    "There is no such thing as a bad day fishing!"

  15. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #15
    Quote Originally Posted by J Risco View Post
    Am I missing something here?

    First question, is an oil prime sequence and 2 hours of double oil required after an injector service?

    Second question, if it is required, why would you do plugs while reassembling, then have to do them again after 2 hours when you are done with double oil?
    There is difference between an OIL PUMP PRIME and "Break-In Reset".

    BOTH prime the oil system.

    An Oil Pump Prime does NOT reset Break-In. This is the BEST method to ensure the oil system has been purged of air anytime that the intake/reeds were apart, any oil line after the engine-mounted tank is disconnected, or the air compressor has been replaced. This procedure is done with the Computer Diagnostic System (a Dealer Tool), or a DDT.

    I strongly recommend AGAINST doing any Break-In Reset, and you are correct- it consumes DOUBLE oil for approximately 2 or more hours. This procedure is only meant/intended when a powerhead has been replaced or rebuilt.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  16. Member J Risco's Avatar
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    #16
    Thank you Don! So I can simply have an Oil Pump Prime done after re-installing everything from an injector service and avoid double oiling. Makes more sense to do the plugs while apart now haha.
    2021 Phoenix 920 Elite / SHO 250
    Bullet 21XD / 250 XB (Gone to a great home in LA)
    "There is no such thing as a bad day fishing!"

  17. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #17
    Quote Originally Posted by J Risco View Post
    Thank you Don! So I can simply have an Oil Pump Prime done after re-installing everything from an injector service and avoid double oiling. Makes more sense to do the plugs while apart now haha.
    And on Optimax Models- if ALL you did was R&R the rails/injectors/direct injectors: NO oil pump prime is required.

    See Post #15 above.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #18
    Thanks for taking the time to write that up. Very informative!
    Good timing for me...I hope.
    I have a leaking fuel hose going to the starboard rail. Can the fitting on the bottom of the rail be taken off and replaced? I have the retaining plate off, not sure what to do now.
    Thanks

    Never mind.... Search is my friend
    Last edited by eric n; 01-30-2016 at 01:46 PM.

  19. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #19
    If that hose is leaking, REPLACE THE HOSE. It's sold as an assembly- and most leaks (especially at the starboard side) are actually the hose leaking (very seldom is it just an "o-ring").

    Can be addressed simply during injector/rail servicing (be sure to note this problem to whomever is performing the service).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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    #20
    Quote Originally Posted by SilverFox579 View Post
    If anyone has specific questions, I'd be happy to share my personal experience.
    I have a 2001 optimax and I think I have a bad fuel injector, my rpm is 5 grand wot. I probably need to take it to the shop and have them look at it. My question is would it to much trouble changing out the fuel injector myself ??

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