"water in gas"

I have a 2009 Nissan 4hp outboard motor (model #NSF4B2). I've owned it for two years and had no problems during the first season of use. But early last year it would not start or stay running if it did. The local authorized service center said there was water in the tank and advised I used ethanol-free gas. I heeded his advice, put the motor on the boat and it ran fine for about 15 minutes. Died and would not start again. This time, I took it to a different servicer but the diagnosis was the same. I put it back on the boat and it ran for about 5 minutes. Would not start again.
I'm not a mechanic in any way and considering the lack of advice I've received from the service centers, I'm not sure what to try next. Despite looking new and shiny, it won't sell. So I thought I'd try this forum. Any suggestions/ideas would be appreciated in case our lakes get rain some day.
Thanks,
Scott

Scott,

If you have had water-contaminated fuel, the entire fuel system needs to come apart, and everything needs to be flushed out. If you open the carb drain and the liquid that comes out forms droplets on the oily/painted engine, it is water. If it spreads out in a fine sheet, it's not water. If nothing comes out, either there isn't any gas in the carb, or the drain is corroded/clogged. Scrap all the old gas. The fuel pump may have crud in it; that can be disassembled and cleaned. Disassemble and inspect the carb. May have corrosion from water. If so, a new one is a little over $100. Are you using a remote tank, or the onboard tank? The onboard tank can be tricky to completely drain. We sometimes empty them as much as possible, and then flush with ether, acetone, or alcohol, and then re-flush with fresh gas before reinstalling the tank. If using a remote tank, the primer hose must also be drained and flushed. If the pump is starting to act up, fuel may not run through it (by gravity alone) very easily, and you may see that symptom by a lack of fuel reaching the carb (from the onboard tank) under gravity alone.

In any event, the usual advice applies: Diagnose, then repair. In the future, you must always run the carb out at the end of each and every day.

Onboard tank. Sounds like I just need to get my hands dirty despite the asc. Thanks very much for the good info.

add a water filter..especially if its a built in tank.....the kind that looks like an automobile oil filter...about 30 bucks at west marine plus any fittings you may need...with ethanol this is no longer an optional feature...

No way possible for that. The integral tank (which holds about 1.4L), can't accent anything like that. Papy, you're thinking of a built-in-to-the-boat tank. Regardless, with E-10, if you add water, the alcohol drops out with the water, lowering the octane rating of the fuel, making it essentially worthless as outboard gas.

Thanks Paul....overlooked the size of the motor...however adding a water filter is standard procedure with the mercury dealers down here....have run one for 2 years on a 2011 60hp 4 cycle with e10....

Yes, water separators are good. They come standard with any new Tohatsu from about 25 or 30 hp on up.