20 hp Tohatsu fuel issues

Carpediem44DB

Carpediem44DB

Well-Known Member
Aug 18, 2015
3,230
Sanfransico Bay area
Boat Info
2000 Carver 506
2006 44 DB Sedan Bridge
Engines
Volvo TAMD 74 P
A fellow CSR member has a Tohatsu 20 horse outboard on his 10 foot dink. Lately it has been running rich and stalling when power is reduced to idle at neutral and stumbling in mid range power . We noticed too that there is a strong smell of raw fuel and a sheen on the water after the engine quits. We traced the fuel to the hose attached to the bottom of the fuel bowl. Does anyone know what condition would cause fuel to drain from there? Clearly its by design to overboard the fuel but would it be a mixture adjustment or a float valve leaking past? Ideas?
Thanks
Carpe Diem
 
Is the needle stuck open? Pull the carburetor and check that the float is okay.
 
Carpediem44DB said:
A fellow CSR member has a Tohatsu 20 horse outboard on his 10 foot dink. Lately it has been running rich and stalling when power is reduced to idle at neutral and stumbling in mid range power . We noticed too that there is a strong smell of raw fuel and a sheen on the water after the engine quits. We traced the fuel to the hose attached to the bottom of the fuel bowl. Does anyone know what condition would cause fuel to drain from there? Clearly its by design to overboard the fuel but would it be a mixture adjustment or a float valve leaking past? Ideas?
Thanks
Carpe Diem
Click to expand...
Rebuild the carb... I do my Yamaha every 2 years.
 
There is a Tohatsu dealer/ service shop not too far away, I advised him to take it there for a complete service and carb rebuild. He will be much happier and so will I:)
 
Guys, I read the sailing magazine websites. Blue water off-shore trans-ocean sailing. Amazing stories on there. Good stuff. They all bitch about how ethanol fkd up outboards. But the farm lobby is bigger than the motor/boats lobby. Do you know that if you put gas with ethanol in your engine it voids warranty? Ya. I live in Maryland. There is no pace to get fuel without it.
 
It's totally the carb needing cleaning out. Rebuild is bad term for it, but thats what it is called. The low speed passage and jet get clogged with micro crap from ethanol and causes this. Like @ocgrant said, every two years for sure. Even new outboards have this issue. Big PITA for sure.
 
I just disconnect the fuel connection to the motor every time and let the motor run until it dies... Never had to rebuild anything 10+ years running.
 
The Bill Collector said:
I just disconnect the fuel connection to the motor every time and let the motor run until it dies... Never had to rebuild anything 10+ years running.
Click to expand...
I agree with this, I do the same. Key is to burn off all the fuel so it can’t evaporate in the carb and leave the tarnish behind.
 
I had a 4HP Mecr (Tohatsu under the hood) for about 7 years. It did the same thing. Took it to the shop. They cleaned the carb. Ran fine after. But eventually traded it in on a 9.9 Suzuki with fuel injection. No problems since.
 
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