Pontoon Boat & Deck Boat Forum

I have a 2009 150 Merc 2 Stroke Fuel Injected, very low hours. I took it out of the barn for a spin a couple of weeks ago and it ran rough died in neutral a couple of times and did not have its usual top end. The 3/4 tank of gas in it was treated at put up last year and I topped it off this year. I am thinking it is bad gas because it ran perfect when I put it up. The local merc dealer says don't run it because it could drop a piston. He says the rule is if it is not running right don't run it at all. Does this sound right?

That's my feelings with any 2 stroke, things go wrong in a hurry with a lean condition on them. I'd start with a set of plugs and change any filters you have to start with.

Years ago my former boat with a 60 HP Mercury two stroke sat for about 18 months in storage. I treated the gas with Stabil before storing it. When I was finally able to use it, it started but ran poorly. It got progressively worse and I was not smart enough to recognize the warning signs. Eventually, the motor seized. Diagnosis was a burnt piston caused by a gummed up carb. The gas must have been bad and gummed up the carb. That made it run lean and not get the lubrication it needed from the oil mixed with the fuel. So bad gas cooked my motor.

I learned afterward you can safely use a lot more Stabil than the label recommendations, and you should use more if you're storing for an extended time. I always err on the heavy side now.

The boat and motor were over 10 years old at the time and the estimate to repair the motor was more than I was willing to pay for an old boat and motor. Ended up selling the whole rig at a loss. Good luck with yours.

rancherlee wrote:That's my feelings with any 2 stroke, things go wrong in a hurry with a lean condition on them. I'd start with a set of plugs and change any filters you have to start with.

I agree about changing the plugs and check the fuel filters. And I'd also suggest turning over the fuel tank--to treated 100% gasoline. Then take it slow and easy.