2004 Tohatsu 3.5 hp fuel leaking from carb

giswspro

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I am new to boating. My 2004 Tohatsu 3.5 hp 2 stroke started fine this morning. It usually starts at first or second pull. About 200 ft away from the slip we stopped the engine for fishing. Then the engine could not be started again. We noticed fuel leaking from behind the control plate - the carb? Later at home I removed the engine cover, and removed the control plate, and found out the fuel was freely coming out of the carb if fuel line was open. I am not sure what is causing the fuel leaking. Can I fix it myself, or do I have to send it to some marine shop? Thanks for advise.
 

pvanv

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Apr 20, 2008
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Assuming your model is M3.5B. Likely a stuck float or maybe a worn needle. Disassemble the carb, clean and inspect. May need a new needle and seat.
 

Sea Rider

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Was the engine trimmed all the way up to its locking position when seeing fuel spills at front carb ? If so, sometimes does so, need to close fuel lever and air vent before trimming all the way up. Doesn't matter if you have changed the whole carb interior spare parts, likes doing that. it's near a motorcycle carb being too darn simple and primitive.

If you have build in tank pressure while air vent is closed can spill too, worst if needle and needle valve are not in their top working order.

Happy Boating
 
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giswspro

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Paul and Sea Rider, Thanks for the advice.

Model is M3.5B. The fuel leaked from carb whenever fuel **** was open. The fuel comes out from the carb freely, not just a few drops. I will try to figure out how to do the carb disassemble and clean next - being new to boating I have never done it before.
 

Sea Rider

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Definitely not just drops, would say old man pissing like. Have not answered if the issue was while engine was trimmed all the way up in its locking resting position and in plain summer where there is excessive heat/pressure buildups inside fuel tank while vent is closed and fuel **** opened.

Happy Boating
 

giswspro

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Sorry have been away and only saw your question about engine trimming to its locking position now.

I typically have the engine locked on the boat and then open up the fuel **** and fuel will leak out of the front carb steadily. I did try to clean up the carb and that helped a few days. Then one day I was planning to go fishing so added full fuel to the fuel container, opened the fuel ****, and fuel leaked out of the carb again. I have not used the engine for two months now.

Is it possible that I added too much fuel to cause this leaking?
 

Sea Rider

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It's not a matter on how much fuel you add, definitely is a carb related issue. Seems that needle is not being properly sealed inside valve seat by float. Have had same issue with same 3.5B, ended replacing needle, needle valve, float, float hinge and bowl gasket. Can't say which specific part cured the issue, strange was that all old mentioned parts were mint cond.

That 3.5 uses a motorcycle carb model and prone to be overfilled if with fuel tank build-ups specially during summer time. So would advise prior to opening fuel ****, open air vent to releasee fuel pressure inside tank, then open fuel **** and start the engine, When about to shut engine off, do you let engine run to consume all fuell on bowl till engine dies or just close fuel **** and tank's air vent and shut engine ?

Happy Boating
 

giswspro

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I usually just shut down the engine and then close fuel ****. Should I close fuel **** first and let engine continue running until it dies?

I will try let air out before open fuel **** in the future.

Thanks for the help!
 

Sea Rider

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Being a 2 strokes engine is much better to consume all fuel on bowl till engine dies, keeps carb in mint clean cond and trouble free from varnishing effect if sitting for long time periods.. With engine on close fuel **** till dies, close tank's air valve. Reverse procedure for next start.

Happy Boating
 
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