Are fuel treatments (like Seafoam or Gumout) worth it?

[fairdeal]

The owner's manual doesn't even mention the vapor separator, so I didn't think to drain it. I can see the service manual tells you how to drain it, but it doesn't say why or when to do it.

there's a "sticky" post here on this forum - "Winterize, Off season Storage"

the post is a bit odd - guess it was written by a "mod"? -

but it includes a link to download a .pdf of a Yamaha "Marine Technical Guide" article
that IMO is helpful

[rejesterd]

I make up a ****tail in a separate jug. stabil, and a decarber. Run the boat till the engine quits on the main tank, then switch to ****tail jug for ride home.

get boat in its final resting place, disconnect gas jug, fire up engine, when its starts to run out of gas I start spraying fogging oil into throttle bodies. Engine quits, then I drain VST, and filters.

I did something similar last fall. I ran a mix of fuel, stabilizer, and Yamaha's EFI fogging oil through the engine for 20 minutes or so. I did not spray directly into the throttle body though. I also didn't drain the vapor separator. The owner's manual doesn't even mention the vapor separator, so I didn't think to drain it. I can see the service manual tells you how to drain it, but it doesn't say why or when to do it.

[oldmako69]

Something to think about is that the pump in VST is lubricated and cooled by the gas running thru it as it pumps.
running out of fuel means no cooling or lubrication to that motor/pump
they put that pump in the Vapor Separator Tank so that it gets only liquid fuel to pump.

I would never make it purposely not get that liquid fuel while it runs

I am fairly confident that my Hi PSI fuel pump crapped out due to this exact problem. For whatever reason, my engine would not stay running at low power settings and the Hi-PSI pump was continually running without cooling and lube. As a result, the Hi PSI pump shat the bed. I replaced it (along with the Lo-PSI pump) and was rewarded with butter smooth ops.

I never let a two cycle engine run out of gas for a similar reason. No lube.

[rejesterd]

Something to think about is that the pump in VST is lubricated and cooled by the gas running thru it as it pumps.
running out of fuel means no cooling or lubrication to that motor/pump
they put that pump in the Vapor Separator Tank so that it gets only liquid fuel to pump.

I would never make it purposely not get that liquid fuel while it runs

Yes, that's what further googling also suggests.. so I think my conclusion is that you need to treat any gas that's going to sit in the tank or inside the engine for longer than 30 days or so. Otherwise, it's not needed. And don't run EFI engines dry.

[99yam40]

Something to think about is that the pump in VST is lubricated and cooled by the gas running thru it as it pumps.
running out of fuel means no cooling or lubrication to that motor/pump
they put that pump in the Vapor Separator Tank so that it gets only liquid fuel to pump.

I would never make it purposely not get that liquid fuel while it runs

[scofflaw]

That makes sense to me. I'm not sure if you winterize your boat, but if you had to winterize it, would you run the engine dry before storing it? I thought about doing that last fall, but then became concerned about the injectors (or other things) drying up and breaking. So I just treated the fuel with stabilizer and ran Yamaha's EFI fogging oil through it for a few minutes. But if it's safe to run the engine dry and empty the fuel tank in the boat, I'd rather do that since it doesn't cost me any extra money.

I make up a ****tail in a separate jug. stabil, and a decarber. Run the boat till the engine quits on the main tank, then switch to ****tail jug for ride home.

get boat in its final resting place, disconnect gas jug, fire up engine, when its starts to run out of gas I start spraying fogging oil into throttle bodies. Engine quits, then I drain VST, and filters.

[rejesterd]

injected motors do not have the rail vented to atmosphere, so the fuel cannot evaporate.
treat the fuel and make sure it is everywhere in the system before storing

I'm not concerned that fuel left in the injectors is going to evaporate over the winter. I'm just wondering what damage can result if they are intentionally run dry? If none, I don't see a good reason to ever treat the fuel, because I can just dump it all before it gets old enough to cause any problems.

I realize this is probably a whole other thread discussion, but I'm just trying to understand why people are so concerned about treating the fuel in their modern outboards but not in their cars. The engines work generally the same way, so I don't really get it.

[99yam40]

injected motors do not have the rail vented to atmosphere, so the fuel cannot evaporate.
treat the fuel and make sure it is everywhere in the system before storing

[rejesterd]

WOT every trip for several minutes.

Don't add fuel unless your gonna burn it

That makes sense to me. I'm not sure if you winterize your boat, but if you had to winterize it, would you run the engine dry before storing it? I thought about doing that last fall, but then became concerned about the injectors (or other things) drying up and breaking. So I just treated the fuel with stabilizer and ran Yamaha's EFI fogging oil through it for a few minutes. But if it's safe to run the engine dry and empty the fuel tank in the boat, I'd rather do that since it doesn't cost me any extra money.

[oldmako69]

Am I wrong?

(Yes, that was a Big Lebowski reference in case you were wondering.)

"You're not wrong Walter, you're just an a$$hole!"

"All right then"

[scofflaw]

Thanks, this is my feeling as well.

Also agree, Yami outboard, E 10,87 octane, no top tier or additives for me. WOT every trip for several minutes.

Don't add fuel unless your gonna burn it. Big boat up North that I slip gets marina valve tech...plenty of additives there...but who knows exactly what but E10 is the base at 89 octane

[99yam40]

Seafoam has been around since they used regular motor oil to mix with gas for 2 strokes.
it has be around a very long time and used to remove a lot of that carbon that was built up in the combustion chambers and exhaust.

Ringfree is expensive but goes a long way when added at a everyday mix. I will help keep the rings from sticking from carbon build up .

I usually run a seafoam clean out mixture when I 1st get a used motor just to clean it up the best I can to start with.

then use a good oil at the proper ratio, and avoid running old bad gas.

Small tanks can help as you have a quicker turn over of the fuel.

having 100 gallons of old bad fuel in large tanks and adding new good fuel makes a lot more bad fuel.

[rejesterd]

I can't imagine that is necessary with todays 4 strokes, just clean clean fresh gas.

Thanks, this is my feeling as well.

[rejesterd]

The more I think about this, it seems that I'm asking the wrong question. The question of "is Seafoam/Ring-Free worth it?" is too vague. I think my real question is: what problems can result from never treating your fuel with Seafoam/Ring-Free if you're already buying TopTier gas and you use it up within 30 days?

In my mind, the answer is: no noticeable problems will occur. Of course there will always be a small amount of old fuel left in the very bottom of the fuel tank, and that will mix in with newer fuel when you fill up next time. But if you consistently run the tank down to almost empty before refilling, the percentage of old gas that gets sent to your engine is extremely small and isn't going to grow over time.

Am I wrong?

(Yes, that was a Big Lebowski reference in case you were wondering.)

[oldmako69]

Fresh gas is probably more important than Top-Tier gas. So, fresh Top-Tier is obviously the way to go. I add Startron Enzyme Fuel Treatment at each fill (unless I am going to run offshore and burn a whole bunch of new / fresh fuel all at once). But, I am adding the Startron to try and maintain the fuel itself. I don't even consider that it might aid in keeping the combustion chamber and exhaust path free from excessive carbon.

In winter I also use Marine Sta-bil since my yot sits.

20 years ago I "saved" a 23-year old OMC with sticking rings by removing the exhaust plate and then manually tapping on the piston rings (using a home made chisel-shaped, oak tool). I sprayed a ton of aerosol penetrant directly on each piston, banged on the rings a bit and then walked away. I repeated this treatment over a period of days. After I put it all back together, I ran a can of sea-foam through it. The increase in compression for each cylinder was dramatic as they had "carboned-up" significantly.

But, that was an old pre-mix two stroke. I can't imagine that is necessary with todays 4 strokes, just clean clean fresh gas.

If I ever buy another 2 stroke and its pistons all gummed up, I'm going straight for the Drano! I'll post a vid of the pre and post compression tests and the big smoky event in between as well.