25hp Tohatsu motor won't plane out under load

[LM Barnett]

I have an 04 2-stroke Tohatsu (Nissan) motor. I noticed a problem at the beginiing of duck season. When I am in the boat by myself it seems a little sluggish on take off (but will palne out eventually), and gets more sluggish the more weight that is in the boat, up to the point where it won't plane out with 3 guys (with waders shotguns, and decoys) in the boat. It ran fine with 4 guys last year. I have changed gas (with new seafoam), and changed the plugs, and it is still happening. The rubber clutch is not slipping, it won't "wind out" with a load.

Any suggestions would be helpfull.

Matt

 

[TOHATSU GURU]

Re: 25hp Tohatsu motor won't plane out under load

Probably a dirty carburetor. Take it off, take it apart, soak it in carb cleaner and put it back on and try it....And when your done using the engine at the end of the day, disconnect the fuel hose and let the engine run itself out of gas.

 

[LM Barnett]

Re: 25hp Tohatsu motor won't plane out under load

Probably a dirty carburetor. Take it off, take it apart, soak it in carb cleaner and put it back on and try it....And when your done using the engine at the end of the day, disconnect the fuel hose and let the engine run itself out of gas.

Had the carb cleaned at the Nissan certified mech. in Sherwood, and it is still happening, although the plugs did fowl up pretty quick after he "clened and adjusted the carb for me.

 

[Wee Hooker]

Re: 25hp Tohatsu motor won't plane out under load

A couple of other basic , quick and cheap checks.

Did you try new fuel mix?

Does RPM go up when you squeeze the fuel line ball?

Did you try putting in new plugs?

Did you check spark to both cylinders while under load ( with an inline tester?)

Put Tach to it to check RPM's?

 

[TOHATSU GURU]

Re: 25hp Tohatsu motor won't plane out under load

Carburetor cleaning is a relative term. Some mechanics spray cleaner into one and call that cleaning it. Some take one apart, use that same spray can on all the goodies and call that cleaning it. Old fossils, like myself, believe that the only way to clean a carburetor is by taking it apart, soaking the correct bits in a pail of carburetor cleaner...Sometimes two or three times and then putting it back on. I would really urge you to revisit the carb before you do anything else. If the engine still lacks power then it's time to pick one system and start detailed testing.

 

[LM Barnett]

Re: 25hp Tohatsu motor won't plane out under load

A couple of other basic , quick and cheap checks.

Did you try new fuel mix?

Does RPM go up when you squeeze the fuel line ball?

Did you try putting in new plugs?

Did you check spark to both cylinders while under load ( with an inline tester?)

Put Tach to it to check RPM's?

your questions in order: yes, no, yes, not yet, and no.

Carburetor cleaning is a relative term. Some mechanics spray cleaner into one and call that cleaning it. Some take one apart, use that same spray can on all the goodies and call that cleaning it. Old fossils, like myself, believe that the only way to clean a carburetor is by taking it apart, soaking the correct bits in a pail of carburetor cleaner...Sometimes two or three times and then putting it back on. I would really urge you to revisit the carb before you do anything else. If the engine still lacks power then it's time to pick one system and start detailed testing.

Thanks, I will give the shop a call and ask how they do it.

 

[LM Barnett]

Re: 25hp Tohatsu motor won't plane out under load

Checked compression, spark, cleaned the carb, and new plugs, new gas/oil, etc, etc... After talking to a buddy, he told me to check the prop, I looked and on the boat, it looked fine. But I was wanting a SS prop for 2 years now, and decided to order one anyways. When I held the old one next to the "good one" this is what I saw:

 

[LM Barnett]

Re: 25hp Tohatsu motor won't plane out under load

Thanks to all who offered help. Went to the river to run the boat on Friday after replacing, cleaning, tuning... the boat ran pretty good. Went back out Yesterday,a nd put the wifey, and fishing gear, and 2 crappie structures (plus weight) in the boat and went out fishing, and structuring... The boat got on plane, I was soooo happy. Now just got to get the carb set right

Thanks again to all that helped.

 

[pvanv]

Re: 25hp Tohatsu motor won't plane out under load

So... was the primary issue the carb? Or was it the prop all along? Or was it a combination of the two?