Pontoon Boat & Deck Boat Forum

I got all but about 2 and a 1/2 gallons out of my 25 gallon tank. The gas has been in there for 2 years, Will it be OK to fill the tank with new gas or should I get the last 2 gallons out. Having a heck of a time getting it out. Thanks in advance for any help.

I think you will be ok unless it is half water.

I would completely fill tank with E10 ethanol gas and run the heck out of it for an afternoon and before parking boat, completely refill with regular or E10....that is, if you plan on using the boat regularly. If not, I would get it all out of there.

I would think you will probably be okay, but if you can't get it out I sure would fill the tank with fresh fuel, and put some stabilizer in the tank just before you fill the tank with fresh gas. Someone said to use E10 fuel... I would suggest if you can find a station that has ethanol free fuel, you would be much much better off using it. Yes your boat will run on E10, but that ethanol is hell on fuel hoses and in general on outboards.... I think in 10 years I may have used regular E10 fuel twice... every other time it's been e- free. If you don't know if there is a station that sells e free gas in your area, maybe this will help. https://www.pure-gas.org/ Then just click on your state at the bottom, then find your town or city and there will be a list of e free stations in the area.

Yeah puregas , and keep an eye on the octane rating. The station in my town that has e-free is only 86 octane. My motor calls for minimum of 87. I drive to the next town over that has 91 octane. If the old gas has "phased separated" and there much any water in the bottom of the tank, there is nothing you can add to "remix" the water with the gas. Be prepared to empty the fuel bowl (filter) out on the lake if necessary.

I suggested the E10 for the first tank, not sure if I am correct but my understanding is E10 will absorb water that could be in the tank since its been sitting so long and help burn it out as he runs the boat that first day. After that, yes, E free.. that is what I use unless somewhere where I cant find it.

boocat wrote: ↑

Thu Apr 11, 2019 3:31 am

Yeah puregas , and keep an eye on the octane rating. The station in my town that has e-free is only 86 octane. My motor calls for minimum of 87. I drive to the next town over that has 91 octane. If the old gas has "phased separated" and there much any water in the bottom of the tank, there is nothing you can add to "remix" the water with the gas. Be prepared to empty the fuel bowl (filter) out on the lake if necessary.

Most accurate statement, once phase separation occurs its done, you can put all the "new" gas you want in there and all your doing is contaminating good fuel. 2.5 gallons is 10% of a 25 Gal tank, that's not acceptable in my opinion. take the fuel line off the engine, go to harbor freight and get a cheap siphon pump, get the end of the hose lower than the bottom of the tank, boat level, and get that nasty stuff out. didn't see if you were fuel injected or not, but let me tell you, those systems are a lot less forgiving than carbureted engines, at any rate a Lean Burning Engine is a detonation waiting to happen.

I ended up going to buy a pump and got it all out, Thanks for all the advice. Thanks for all the advice.

That’s probably for the best, thanks for the update

Unfortunately, I have been unable to use my pontoon for 1-1/2 years. I’m pretty sure that I added fuel stabilizer the last time I filled up but am not 100% certain. I keep the boat in dry dock about 2 hours away. If I were to drain the old fuel, how and where could I dispose of it? What harm could occur if I were to run it thru the engine (probably 25+ gals)?

I think you have lots of lawn mower gas. Might be safe to mix a gallon or two at a time with a full tank of gas in the car.

maybe lawnmower, worth a try. Mine wouldn't even run in the mower, it ended up along the fence line. Not sure I would use it in a modern car.

As for disposing of bad gas, please don't dump it on bare ground. If you can't find an appropriate disposal site, find a vacant (meaning site not currently in use) and dump the gas where it will evaporate on the surface of the concrete. I'd suggest a covert mission to not get caught too. Or just let it sit outside in a bucket (in a safe location) until it evaporates. Couple of hours in the sunshine and it's gone except for maybe your additives.

I had probably 20+ gallons of gas that had been in my tank for over 1-1/2 years. As I posted above, I had no idea how to dispose of it. So, I added a bottle of Seafoam and 3 ounces of Quicksilver stabilizer, then topped off the tank. Our marina sells only non-ethanol fuel.

The Honda fired right up and idled smoothly. The engine accelerated normally and ran better than it ever has. My RPMs were finally where I thought they should be (5,800@WOT) and GPS speed over 29mph.

This was driving into a strong headwind. This boat always seems to run faster in a headwind. I’m wondering if the Bimini up and the full underpinning may be producing enough lift to reduce the drag in the water.

I’m glad I bought a new marine battery before leaving home. The marina is about 2 hours away. Both boat batteries were DOA.