how long is too long for gas to sit for a 150 merc efi

non ethanol fuel (unstabilized) 30 days treat with red stabil
ethanol fuel (unstabilized) 7-10 days treat with green stabil

What will gas that sits that long do? Make your motor smoke?

Like Steve said.

I was having an issue with my motor not shutting down cleanly and it was because my gas was going bad. Some may want to disagree here, but the day's of keeping your tank full of fuel are gone. You should be putting gas in your boat when you head to the lake and try and burn out what you purchase while on the water. The gas with this ethanol is [censored] after 7 - 10 day's like Steve said. I burnt all my bad gas out and put fresh in and no more problems.

no it won't smoke.

the fuel breaks down, and looses it's octane. makes a boat run terrible!!
if it's ethanol fuel, the fuel and ethanol seperates, and the ethanol will pull in moisture. BAD combination in an outboard.

Steve, not to highjack this post, but did you ever sell your dragster?

What would cause your motor to blow white smoke occasionally? I have a 150 Johnson faststrike, and every once in a while it will smoke after running on plane. After a few mins of ideling it will stop. The motor runs strong and never dies on me. I just bought it a month ago. I figured it might have just had old gas in it. It has been very cold so I figured alittle bit of it might have been from blowing hot air into cold air, but not sure.

When you have a 52 gallon gas tank and you can fill it up for 1.39 a gallon, its hard to only buy 10 gallons at a time, whenever it will possibly hit 4$ a gallon again in near future.

Joey, I completely see your point and I am not trying to argue, but wanting people to be careful with their expensive outboards, so think of it this way.

Lets say today, Tuesday, you have 10 gallons in your tank so you put in 42 gallons and top it off. That is $58.38 of new fuel then you don't get to fish this weekend 01/17/2009. Then you get to go fish the following weekend 01/24/2009 and your fuel has already separated and gone flat. This could cause detenation in your motor (not a good thing) and you possibly blow the thing up.

How does that $1.39 gas look to you now?

This is probably to the extreem, but this fuel we are getting now is really not good stuff and can cause you some real $$ if you don't protect your motor from it.

I know a little bit about fuel because I use to drag race and your fuel has a lot to do with how your performance motor performs and that is what you have on the back of your boat is a performance motor.

This also comes from a very reliable mechanic friend of mine and I think Steve will back me up on this.

ripnlip,
When was the last time you had your motor compression tested? WHITE smoke normally comes from moisture (water) being burned in the cylinder. If your head gaskets have a tiny leak it will get bigger as time goes on. Having the white smoke after running on plane (at your highest compression ratios) and then decreasing or stopping when you slow or idle (lower compression ratio) the water is not "sucked" past the gasket, until it wears out further. Just a suggestion have your motor checked for compression leak down.

how much does that usually cost to fix?

right now i have about 20 gals. of fuel in my boat from about the first of november i did put fuel stablizer in it i used quiksilver fuel stablizer do i need to remove that fuel before filling up the next time.

I have a 150 faststrike and it has been blowin white smoke for ever...at first and then it stops. It blows more when it hasn't been run in a while. I had my stuff looked at last summer when the power pack went out...the compression was fine.Every non EFI engine I have been around blows it.

I think that gas prices may stabilize for awhile now or maybe go down a little. The instability caused with the natural gas supply to Europe have ended and that should take some of the drive to raise prices.

I only put 6 to 10 gallons of gas in my motor each time I fill up. That usually keeps the tank over half full or over 12 gallons. For my boat that will go a long way but if I had to drive a long way I can get around 150 miles if I fill it up.

Well I knew that "what if" would occur, it wasn't my point to argue either. My only point was that it is hard to not keep your tank full when gas is so cheap. That is the crappy part about it all. If I could only figure out a way to stockpile gasoline