Fogging a Merc EFI

C

Cricket Too

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Joined
May 14, 2003
Messages
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First year with this engine and I've been looking around the site at old posts about EFI fogging. It seems as though spraying fogging oil through the intake isn't a good idea due to sensors, although I don't see any sensors that would be in my intake, plus taking the cover off involves 12 allen bolts and looks like the VST has to come off as well, so it's a pain to do it seems.

I know the pull the plugs and spray fogging oil down the cylinders and give a few cranks method, but that won't do much for coating the internals (crank, rods) with fogging oil. When I first got my old Ficht I was told the best way to fog was to pull the internal fuel/water separator and dump out 1/2 the fuel and fill with fogging oil, put it back on and run it to suck the fogging oil in, but that always seemed like it burned it off way too quick to do anything. The Ficht was easier to get at the front to spray oil through the intake than this Merc (250 EFI), so I was thinking about trying the internal fuel/water separator trick, but still not sure that does anything.

Anyway just looking for suggestions on fogging this type of motor from anyone who has one or knows them. Also what is the consensus on draining the VST for the winter, seems like it's a good idea to not leave fuel sitting in it for 4 months.


Thanks.
 
tazrig

tazrig

Lieutenant Commander
Joined
Dec 20, 2012
Messages
1,752
Re: Fogging a Merc EFI

Cricket Too said:
First year with this engine and I've been looking around the site at old posts about EFI fogging. It seems as though spraying fogging oil through the intake isn't a good idea due to sensors, although I don't see any sensors that would be in my intake, plus taking the cover off involves 12 allen bolts and looks like the VST has to come off as well, so it's a pain to do it seems.

I know the pull the plugs and spray fogging oil down the cylinders and give a few cranks method, but that won't do much for coating the internals (crank, rods) with fogging oil. When I first got my old Ficht I was told the best way to fog was to pull the internal fuel/water separator and dump out 1/2 the fuel and fill with fogging oil, put it back on and run it to suck the fogging oil in, but that always seemed like it burned it off way too quick to do anything. The Ficht was easier to get at the front to spray oil through the intake than this Merc (250 EFI), so I was thinking about trying the internal fuel/water separator trick, but still not sure that does anything.

Anyway just looking for suggestions on fogging this type of motor from anyone who has one or knows them. Also what is the consensus on draining the VST for the winter, seems like it's a good idea to not leave fuel sitting in it for 4 months.


Thanks.
Click to expand...

You are correct spraying fogging oil into the air intake will mess with your sensors. Most mechanics that I have talked to are moving away from fogging oil anyway. What is suggested instead is first make up a (a gallon or so) mixture of gas, 50:1 2 cycle marine oil and a good stabilizer like Startron or Stabil etc. The 50:1 takes the place of the fogging oil and it won't mess with your sensors. Next pull the gas line from your tank if you have access. If you don't gain access to it as soon as you can up line from the tank and put it into the gas mixture you just made. Run the motor for a couple of minutes. Replace the hose. Done. This way the 50:1 coats everything all the way through the engine and the stabilizer takes care of the gas leftover in your fuel filter and VST for the 4 months it's sleeping. Don't forget to put stabilizer in your main tank and top it off.
 
C

Cricket Too

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Messages
1,732
Re: Fogging a Merc EFI

Yeah I've heard that technique as well, it makes sense since the VST is already full of 50:1 normally and the injectors are always spraying a 50:1 mix normally, so pulling a 50:1 mix from a 1 gallon tank would coat everything with a 25:1 mix, which I assume would be the same if not better than fogging oil. I run Startron all season long, so it's always treated I just double treat for winter storage. I drained the VST anyway, figure being empty takes out any chance of fuel gumming up or separating in there, but anything leftover in it is double treated with Startron anyway.
 
C

Cricket Too

Lieutenant Commander
Joined
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Messages
1,732
Re: Fogging a Merc EFI

I'm guessing most people don't run a Merc anymore and if they do it's not an EFI. Any Yami owners have any opinions on draining the VST?
 
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