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.
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Originally Posted by SilverFox579
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?
