So here's an update. I found a slick page on the Mercruiser site which I recommend adding to your favorites if you own a Mercruiser:
http://www.mercurymarine.com/serviceand ... drives.php
This is for Mercruiser MPI engines. (In my case, this is for a 2009 496 Mag MPI. ALL instructions are for boat OUT of the water). See link above for variations in model and recommendations from Mercruiser.
ENGINE AND FUEL SYSTEM PREPARATION:
1. In a 23 liter (6 US gal.) remote fuel tank mix:
a. 19 liter (5 US gal.) regular unleaded 87 octane (90 RON) gasoline
b. 1.89 liter (2 US qt.) Premium Plus 2‑Cycle TC‑W3 Outboard Oil
c. 150 ml (5 oz) Fuel System Treatment and Stabilizer or 30 ml (1 oz) Fuel System
Treatment and Stabilizer Concentrate Tube Ref No. Description Where Used Part No. 115 Premium Plus 2-cycle
TC-W3
Outboard Oil Fuel system 92-858026K01124
Fuel System Treatment &Stabilizer Fuel system 858071K01
2. Allow the engine to cool.
IMPORTANT: Immediately wipe up any fuel spills or sprays.
3. Close the fuel shut off valve, if equipped. Disconnect and plug the fuel inlet fitting if not equipped with a fuel shut off valve.
4. Connect the remote fuel tank (with the fogging mixture) to the fuel inlet fitting.
IMPORTANT: Supply cooling water to the engine.
5. Start and operate the engine at 1300 RPM for five minutes.
6. After the specified operating time is complete, slowly return the throttle to idle and shut the engine off.
IMPORTANT: Ensure that some fogging mixture remains in the engine. Do not allow the engine's fuel system to become completely dry.
7. Replace the water separating fuel filter element. Refer to Section 5.
Draining the Seawater System
NOTE: This procedure is written for the air pump that is attached to the engine. However,
any air source can be used.
1. Place the boat on a lever surface to ensure complete draining of system.
2. Remove the air pump from the engine.
3. Ensure that the lever on top of the pump is flush with the handle (horizontal).
4. Install the air pump on the actuator fitting.
5. Pull lever on air pump (vertical) to lock pump on the fitting.
6. Pump air into the system until both green indicators extend and water drains from both
sides of the engine. The port side will begin draining before the starboard side.
7. Verify that water is draining from each opening. If not, use the Manual Drain System
instructions.
8. Allow the system to drain for a minimum of five minutes. Pump air as necessary to keep
the green indicators extended.
9. For DTS engines, pull the lanyard stop switch (if equipped), or disable the ignition circuit
by pulling the fuse marked "CD".
10. Crank the engine over slightly with starter motor to purge any water trapped in the
seawater pump. Do not allow engine to start.
11. Remove the air pump from the air manifold and return it to the mounting bracket.
12. Mercury MerCruiser recommends leaving the drain system open while transporting the
boat or while performing other maintenance. This helps ensure that all water is drained.
13. Before launching the boat, pull up on the manual release valve. Verify that the green
indicators are no longer extended.
Draining the System (Manually)
NOTE: Use this procedure if the air actuated single point drain system fails.
NOTE: It may be necessary to lift, bend, or lower hoses to allow water to completely drain
when hoses are disconnected.
1. Place the boat on a lever surface to ensure complete draining of the system.
2. Remove two blue drain plugs from the seawater pickup pump (front, starboard side).
3. Verify that water is draining from each opening.
4. Allow the system to drain for a minimum of five minutes. Mercury MerCruiser
recommends leaving the drain system open while transporting the boat or while
performing other maintenance to ensure that all water is drained.
5. For DTS engines, pull the lanyard stop switch (if equipped), or disable the ignition circuit
by pulling the fuse marked "CD".
6. Crank the engine over slightly with starter motor to purge any water trapped in the
seawater pickup pump. Do not allow the engine to start.
7. Prior to launching the boat or starting the engine, close the drain system by installing
the two blue drain plugs.