2002 Mercury 225 Optimax runaway Idol

[Dieselfumess]

Greetings.
I have a 2002 Tracker that has a 225 optimax on it. The boat has been sitting for along time. About 6 years..I did drain most of the gas out of it and treated the rest of the gas with seafoam. I also made sure to run it dry of gas to drain the carbs. Then I fogged the carb to help keep the gaskets from drying out.. now I am almost 100 % that this has nothing to do with what's going on. Just thought I would add it anyways. Well I finally got around to fixing the hull problems that I had and attempted to fire up the engine. I put fresh fuel in it and it fired right up. Then all of a sudden
the engine went too maximum rpms and beyond. I immediately shut the engine off. I did look in the shop manual that I have for it and did a little bit of research. What I think happened was the rpm sensor is bad. The one that is located by the flywheel. I haven't attempted to start it again as I don't want to take a chance of blowing the engine. Especially since it's basically a cold start. So long story short. Does anyone have any other ideas on what else to look for or input on the sensor. I just wanted a few other opinions before I send away for a new one. One more thing I should add eventhough I'm pretty sure wouldn't cause the problem is the float in the Reservoir let loose. So I am ordering a new tank. Thanks for any help

[lpugh]

Greetings.
I have a 2002 Tracker that has a 225 optimax on it. The boat has been sitting for along time. About 6 years..I did drain most of the gas out of it and treated the rest of the gas with seafoam. I also made sure to run it dry of gas to drain the carbs. Then I fogged the carb to help keep the gaskets from drying out.. now I am almost 100 % that this has nothing to do with what's going on. Just thought I would add it anyways. Well I finally got around to fixing the hull problems that I had and attempted to fire up the engine. I put fresh fuel in it and it fired right up. Then all of a sudden
the engine went too maximum rpms and beyond. I immediately shut the engine off. I did look in the shop manual that I have for it and did a little bit of research. What I think happened was the rpm sensor is bad. The one that is located by the flywheel. I haven't attempted to start it again as I don't want to take a chance of blowing the engine. Especially since it's basically a cold start. So long story short. Does anyone have any other ideas on what else to look for or input on the sensor. I just wanted a few other opinions before I send away for a new one. One more thing I should add eventhough I'm pretty sure wouldn't cause the problem is the float in the Reservoir let loose. So I am ordering a new tank. Thanks for any help

Optimax motors do not have a Carb and should never introduce anything into the air handler as you have just found out why
Item in red could cause this, Pull the plugs and crank the motor at WOT until it is longer blowing out fuel and fogging chemicals
could have an excess in the crankcase and air handler, repeatedly start it as the RPM elevates shut it off before 2000 RPM
Crank sensor would not cause this

If this does not clear it up, it will need air/fuel pressure test performed
You have already made at least one serious mistake, don't add to it. Please do not take this wrong as this is the best advise you can get
Highly recommend you take this to good Mercury certified tech for a complete physical and service

[leonreno]

A gas leak under the cowl can also cause similar problems.

[Dieselfumess]

Thanks for the advice and I will check it out tomorrow. I do have to bow my head an admit that I might have told a little fib. Because I am not 100% that I did spray anything in there. I always do for the 15hp kicker. But I remember that I forsure ran all of the gas out of it. Pulled the fuel line off and ran it until it stopped..

[lpugh]

A gas leak under the cowl can also cause similar problems.

^^^^^^ sure can such as a water in fuel sensor leak

[Fishing Addict]

Thanks for the advice and I will check it out tomorrow. I do have to bow my head an admit that I might have told a little fib. Because I am not 100% that I did spray anything in there. I always do for the 15hp kicker. But I remember that I forsure ran all of the gas out of it. Pulled the fuel line off and ran it until it stopped..

Just an FYI, I believe the bold is not recommended practice. You should probably take a look at the FAQ Stickies up top.

FAQ- COMMONLY ASKED/USED 2.0/2.4/2.5 Liter Topics (Look here FIRST) Updated 10/2020 (bbcboards.net)

[EuropeanAM]

+1

Your engine is a 3L engine model- going to move it to the correct forum for you.

Please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

[smokewagon]

Greetings.
I have a 2002 Tracker that has a 225 optimax on it. The boat has been sitting for along time. About 6 years..I did drain most of the gas out of it and treated the rest of the gas with seafoam. I also made sure to run it dry of gas to drain the carbs. Then I fogged the carb to help keep the gaskets from drying out.. now I am almost 100 % that this has nothing to do with what's going on. Just thought I would add it anyways. Well I finally got around to fixing the hull problems that I had and attempted to fire up the engine. I put fresh fuel in it and it fired right up. Then all of a sudden
the engine went too maximum rpms and beyond. I immediately shut the engine off. I did look in the shop manual that I have for it and did a little bit of research. What I think happened was the rpm sensor is bad. The one that is located by the flywheel. I haven't attempted to start it again as I don't want to take a chance of blowing the engine. Especially since it's basically a cold start. So long story short. Does anyone have any other ideas on what else to look for or input on the sensor. I just wanted a few other opinions before I send away for a new one. One more thing I should add eventhough I'm pretty sure wouldn't cause the problem is the float in the Reservoir let loose. So I am ordering a new tank. Thanks for any help

If your boat has a Hot Foot check for a broken pedal return spring or binding of the throttle cable.