View Full Version : Fogging EFI Engines

08-08-2004, 10:17 AM
I found an interesting link on the BoatTest.com web site about fogging an EFI engine which is a WMP file (audio/video clip). Has anyone seen this? I don't believe this is how you fog an EFI, at least what I've gleamed from this site and others, but it is interesting even though its a Merc instruction video. They use mixture of gas, 2-stroke oil, and stabilizer mixed in a gas can and then hook it up to the motor and run for 10-15 minutes. I know, this sounds like for an outboard, but this is for a Merc V8.

Here is the link http://www.boattest.com/engines-stern.aspx

08-08-2004, 02:26 PM
I'd like to see a follow up on this procedure to see if the oils have any bad effects on the injectors. This may be OK on the boats with the fuel pump on the motor, but I don't know that it would work on the ones with the in-tank pump/filter.

08-08-2004, 03:56 PM
I've always fogged an EFI motor through the spark plug hole, then pull the coil wire, reinstall the plugs just hand tight, turn it over a few times and repeat - which takes all of 4 minutes to take the plugs back out, spray, and turn it over again.

08-08-2004, 06:42 PM
That works for the cylinders but their point in the video was getting the oil to the intake valves and injectors. If the fuel line is as easy to get to as a Mercruiser, their way works fine. Unfortunatley, they didn't have any Indmar motors in their list. If fogging oil is sprayed into the carb or throttle body and you see heavy smoke, it definitely got to the whole intake.

08-09-2004, 12:38 AM
I agree Jim, Merc's approach to fogging the engine is something I have never heard or read about. It would be interesting to see follow-up testing and specifically on Indmar engines. So tell me again where you would spray the fogging oil on an EFI/MPI LTR. I seem to recall that you take of the flame arestor, then move some plate just after the flame arestor, and squirt away until you see smoke. I can see that I'll have to pull out my notes, as I've forgotten the exact procedure.:D

08-20-2004, 11:33 PM
As JimN suspects, Merc has the fuel pump on the engine. On my last Merc V8 EFI, the process was to
- add stabilizer to gas tank and run it
- remove the water separating fuel filter
-- pour out half of the gas inside the filter
-- replace the half with 2-stroke oil
- reinstall the fuel filter
- disconnect fuel line from gas tank
- run the engine until it burned the fuel / oil out of the filter

seemed to work fine - that engine never gave me any trouble