Outboard motor question

Ok, guys / gals, I have a question on my outboard. I have a 25 HP Tohatsu. I went and ran it Friday afternoon and it would barely run and had a very bad miss while running. Well I changed the spark plugs out and ran it again yesterday and it ran like a champ! My question is when I was running it, there was a lot of smoke coming out the exhaust port. Normally there is some smoke coming out of here and some water mist also. There was only smoke and no water mist. I did feel the water running out of the pisser and it was luke warm but not hot. Not sure why this was and have had several possibilities and would like yalls opinions. Now when I removed the old spark plugs, there was some oil on the plugs.
Thanks for any help you all can offer.

Dwayne, is that 2 stroke or 4 stroke?
First I’d think the smoke was from build up in cylinders had excess unturned fuel build up from bad plugs and it was burning that out.
Then I would think maybe with not being there that water temp might be playing a part in lack of mist. With Luke warm water at pee tube tells me motor is not getting warm which can also contribute to more smoke. Think I would consider changing thermostats. Hotter motor gets more water is going to come out exhaust. I bet your fuel economy has gone down some also. Motor running cold will cause fondled plugs also. Hope this helps some and makes some kind of sense.

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Originally Posted by Cray

Dwayne, is that 2 stroke or 4 stroke?
First I’d think the smoke was from build up in cylinders had excess unturned fuel build up from bad plugs and it was burning that out.
Then I would think maybe with not being there that water temp might be playing a part in lack of mist. With Luke warm water at pee tube tells me motor is not getting warm which can also contribute to more smoke. Think I would consider changing thermostats. Hotter motor gets more water is going to come out exhaust. I bet your fuel economy has gone down some also. Motor running cold will cause fondled plugs also. Hope this helps some and makes some kind of sense.

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Cray, it is a 2 stroke. I don't believe I have a thermostat on my motor, don't really need it here in the south and I mainly run in SHALLOW water marshes, the thermostat is more a problem when running in shallower water. Your diagnoses of it burning off the unburned fuel is exactly what my brother (the mechanic out of the 2 of us) thought it was also. My main concern was no water mist coming out the exhaust and I have talked to a couple of different people that thought this was probably because the impeller was getting weak and needs to be changed out.
Well I ordered a impeller kit and plan on changing that out and also changing out the lower unit oil and hopefully I will be good after that. Thanks for the reply and I'm open to any more suggestions if you or anyone else has any more.

Dwayne give me year model of your motor. I can just about promise you that you have a thermostat in your motor and they are essential to proper running on a 2 stroke. If you give me year I’ll look it up and see what I find.

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Originally Posted by Cray

Dwayne give me year model of your motor. I can just about promise you that you have a thermostat in your motor and they are essential to proper running on a 2 stroke. If you give me year I’ll look it up and see what I find.

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It says 2001 on the tag but couldn't find any parts for the 2001 so I think it is considered a 2002. The Serial # is 62786 and the model # is M25 C3 372 It is a 25 / 30 Tohatsu.

Here is parts diagram. #11 is your thermostat.
Tohatsu 2002 M25C3 - 2 Stroke Tohatsu OEM Parts Diagram for Cylinder Crank Case Assembly | Boats.net

Your right must be 02 only thing listed under 01 is a 40 and 50. Hope this helps.

Thanks Cray! That will definitely be some useful information there!

And changing an impeller is extremely cheap insurance to protect your motor. I sheared the vanes on an impeller on a 25 Johnson and it got hot enough to blister the paint on the head. Motor started running rough and I realized that it wasn’t pumping. Shut it down and thankfully it wasn’t hurt. Cleaned the pieces of impeller out and put a new one in and away it went.

I'd change both pump and thermostat. Call it preventive maintenance. Be careful on the thermostat housing bolts. I know it's been around da salt.
I try to only us OEM parts.
U can test the thermostat in a pot water on da stove.

I talked with PS on dat 25 merc a few weeks ago. Would have bought but da new roof came first. Good price and it is electric start.

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Originally Posted by jig rig

I'd change both pump and thermostat. Call it preventive maintenance. Be careful on the thermostat housing bolts. I know it's been around da salt.
I try to only us OEM parts.
U can test the thermostat in a pot water on da stove.

I talked with PS on dat 25 merc a few weeks ago. Would have bought but da new roof came first. Good price and it is electric start.

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Yea I know about testing thermostat on the stove, did that with a van thermostat. As far as this motor being around salt, well that was probably 10 + years ago! I have another boat for the salt water! But I do live in Big Lake so we have salt in the air so yes it still has some around it.