Is fogging really necessary?

I'm finding my rig runs even more rough at idle than it did last season. Only thing that has changed as far as I can tell is the carb has now been saturated with fogging oil. Next week this carb comes off and a reman goes on. But I'm not so certain that this fall I want someone loading this one up with fogging oil. Hence the question.

Re: Is fogging really necessary?

IMO, the only reason to fog is to coat the cylinder walls so they won't rust during layup. You could bypass the fuel system entirely. Pull the plugs, spray directly into the cylinders, then spin the motor a few revolutions to distrinute the oil. You should be good.

My .02

Re: Is fogging really necessary?

When they fog my twin girls they spray the fogging oil it into the carbs.
I don't know why they would put it your gas tank instead of doing it the right way ??.

[FONT=Arial, Helvetica, sans-serif]Fog the intake--gasoline engines only
While the engine is running, remove the flame arrestor and spray fogging oil into the air intake. Give it an extra heavy shot just as the engine starves and dies.[/FONT]

Click to expand...

Re: Is fogging really necessary?

I just purchase a new 30 hp Merc. When he was talking about winterizing, he didn't say anything about fogging. I don't fog my lawn mower or snow blower when I put them away and they start right up when I need them. I think I would pull the plugs and spray into the cylinders like JoLin said.

Re: Is fogging really necessary?

airdvr1227 said:

I'm finding my rig runs even more rough at idle than it did last season. Only thing that has changed as far as I can tell is the carb has now been saturated with fogging oil. Next week this carb comes off and a reman goes on. But I'm not so certain that this fall I want someone loading this one up with fogging oil. Hence the question.

Click to expand...

When was the last time your 1991 boat has been treated to:
compression test, plugs, wires, dist cap, rotor, points check/replacement (if equipped) coil test, ignition timing check, idle mixture adjustment, idle speed adjustment, float level check, fuel filter, flame arrestor cleaning, electrical connection cleanup/battery cable check...I probably missed something.

I also am a little confused why a reman carb needs to go on your ride when a shot of carb cleaner would remove the fogging oil residue in about 10 seconds...Maybe 10 minutes if you need to pull the float bowls and clean it internally (and which would not be the result of fogging). Fogging oil NEVER reaches the internal fuel passages of the carb if they shoot it thru the air horn. Therefore it shouldn't impact run quality at all. It's just not physically possible...which is I think what Summer Fun may have been trying to say.

Now the fogging oil very well COULD have fogged a spark plug. This is quite common. And this could very well cause a misfire at idle.

I guess what I'm saying is that I pretty much doubt your fogging oil has caused your rough idle (with the possible exception of a fouled plug). If it were me I'd first do a comprehensive maintenance tune-up and follow a troubleshooting procedure before randomly throwing large parts like carburetors at a rough idle problem.

To answer your question directly: Depends on storage conditions. I personally don't fog because my boat spends it's winters in heated indoor storage. But I would fog if mine sat outdoors or in unheated storage that was subjected to temp fluctuations and the resulting condensation that could occur.

Re: Is fogging really necessary?

And fogging oil NEVER reaches the internal fuel passages of the carb if they shoot it thru the air horn. Therefore it shouldn't impact run quality at all. It's just not physically possible...which is I think what Summer Fun may have been trying to say.

Click to expand...

Yes, You said it better than I did thanks.

Re: Is fogging really necessary?

Full tune up last summer. Plugs, wires, points, condensor, and timing. Haven't done a compression check simply for the fact that getting the plugs into that setup was bad enough. I might have slit my wrists trying to get a comp check. Do a search on here about changing plugs in a 351W.

I guess what you;re saying about fogging oil not getting into the deepest parts of the carb should be right but there is a coat of dirty oil all over the outside of the body and horn. I did the tune-up last summer trying to get rid of the rough idle and the black smoke at idle which I attribute to running rich. Didn't change a thing.

I suppose I could try spraying carb cleaner all over everything but that just seems like it would make a mess on the intake. It just seem unnecessary to oil down the inside of the motor. Like someone said I don't do it to my yard equipment.

Re: Is fogging really necessary?

back to the original question... growing up, we had all kinds of boats, usually at least 2 or 3 at a time. NEVER, ever, was one fogged, and all stored outside. The only maintenance done was change the lower unit oil at the end of the season. Not even spark plugs, until they looked bad enough or it started to get hard to start. All the motors ran great, and only lost one through the years, due to an external electric oil pump failing.

So is it absolutely necessary? nope.

Re: Is fogging really necessary?

I think this is where DonS should chime in. . Something doesn't smell right on this.

Re: Is fogging really necessary?

Can you get away without fogging? Sure!

I'm sure thousands, even millions of lawn mowers, chainsaws, outboards etc. etc. survive the winter just fine every year. But not fogging increases the chance of having a seized engine in the spring. This is not something I am willling to take a chance on.

Each to his own.

Re: Is fogging really necessary?

Fogging 2 cycle outboards running 50::1 fuel provides a small amout of protection, if any. There is already 2 cycle oil everywhere. Fogginf a 24::1 motor is silly.

Fogging an I/O provides oil to the top of the cyinders and the intake and exhaust manifolds. This has some real value.

Re: Is fogging really necessary?

I would look at fouled plugs first myself, excessive oil leads to heavy carbonization of the internal parts, IE sticky piston rings, valve buildup, fouled plugs. It can lead to engine run on as well.

Re: Is fogging really necessary?

Fogging has trashed plugs every time I used it. So now I have a fresh set of plugs ready to install after starting the motor in the spring. Wait for the smoke to go away, then install fresh plugs.

Re: Is fogging really necessary?

Had a carb problem last year (running rich) that wasn't fixed by replacing ignition components. So now we blame fogging oil for it????

Pukk the carb apart, soak it, blow it out, reassemble it, set everything to spec, install it, then tune it properly.

FWIW - you may still need plugs again

is fogging required no, but neither is any other maint procedure, just makes things last longer.

Re: Is fogging really necessary?

my 2 cent is to fog it. i'm backed up with my statement by the mercruiser service manual. 2 items in the winterization process (for my rig) refer to getting oil inside the cylinders. once by fogging. which i would think has zero effect on the carb since it's introduced via the venturi. the fogging oil just goes right past the throttle plates and into the engine. it never gets to the internals of the carb since it don't go through the fuel system. 2nd, by removing the spark plugs and introducing 1 oz of fogging oil into the combustion chamber. then rotate the engine to spread out the lub.

only problem i've had with fogging is trying to stall the engine when fogging through the carb. the can just don't introduce enough to stall it. problem cured by filling up a cup with fogging oil and pouring it in. that'll get it to stall.

replacing the spark plugs is part of the summerization process. after the initial start up, which burns up all the fogging oil. new spark plugs are used along with all the other minor tune up parts...

my only variation from the service manual is i just use over the counter fogging oil, not mercruiser stuff. + i just use regular motor oil when i introduce it into the combustion chamber via the spark plug holes.

my lawn mower don't get such good treatment. usually i fog it. but didn't this last fall. no issues noted. but i just wonder if rust was forming inside on the cyl. walls. i didn't look. it started right up too. but my boat deserves the best i can give it. it's my baby ya know...

Re: Is fogging really necessary?

Had a carb problem last year (running rich) that wasn't fixed by replacing ignition components. So now we blame fogging oil for it????

Click to expand...

Not blaming fogging for it, but absent of any other change from last year to this the rig runs worse than ever at idle. Runs great once you put the spurs to it. So what changed? I knew the carb was tired at the end of last year and the reman is sitting in a box in my garage waiting to be installed. I could have not taken her out for a run before I changed the carb but it was a nice evening. The only noticeable difference is the film of fogging oil all over the carb. Regardless of anything else I know a film of oil all over my carb will attract dirt.

So, we'll see what happens when I put the reman on next week.

Beginning to think some of you guys own stock in the company that makes fogging oil...sheesh.

Re: Is fogging really necessary?

The only noticeable difference is the film of fogging oil all over the carb

Click to expand...

sloppy introduction of fogging oil. can't say i've ever got any on the outside of my carb... use a cup instead of the can. it's easier to control..

Regardless of anything else I know a film of oil all over my carb will attract dirt.

Click to expand...

i cover my carb. with a plastic bag and zip tie it mostly closed at the bottom...

begging of season, looks just like it did when i put it to sleep. i've never seen any dirt accumulation, but then i don't get it on the outside of the carb either. if i did, i'd probably wipe it off right then and there after i spilled it...

Re: Is fogging really necessary?

How much old fuel do you have in the tank left over from last year???
add some premium, 1 to 1 of what you have in it and run it almost dry.

Re: Is fogging really necessary?

rbh said:

How much old fuel do you have in the tank left over from last year???
add some premium, 1 to 1 of what you have in it and run it almost dry.

Click to expand...

I considered that. After I woke it up I put about 20 gallons of premium in the tank (44 gal tank). Still I suppose it could be a problem. But I doubt it would be just at idle.

Re: Is fogging really necessary?

airdvr1227 said:

I considered that. After I woke it up I put about 20 gallons of premium in the tank (44 gal tank). Still I suppose it could be a problem. But I doubt it would be just at idle.

Click to expand...

That's true.
What if the float bowl dried out and you had some crud build up, I have seen that varnish stuff CHIP UP ?? and the flakes plug up the orofisses (sp)
Good thing you getting a new carb on it anyways.