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Mkolm 09-28-2020 03:02 AM

Tohatsu M50 d2, 2 stroke fuel problem?
Hi There!

Im a long time reader of this forum, but I cant find anything to help on this topic why I post myself.

I have a 2003 Tohatsu 50hp 2 stroke. Its never really been used, just sitting on a fishing boat that has never been used really. My best guess is around 100 running hours since new.

Ok, so i mounted the engine on a 5m boat this spring, with the intend to start using it. I gave the engine a full service including new gaskets of fuel pump etc.
The engine starts up well and makes the boat take of. but after 1-2 minutes of running the boat in about 20 knots, the engine just bludders away and dies. This lead me to changing the fuel lines all the way from the tank to the carbs, changing fuel filter, cleaning the fuel tank... but the problem wont go away... It also seems like the engine runs better when its cold. I mean, when the engine dies after 1-2 minutes, its hard to start it again.. But if I wait until its cold, it starts easier.

I also find it easyer to get it to run if laborate with the manual choke. Its like trying to find a sweetspot with the choke, somewere in the middle. it starts up better and runs a bit better while doing that.

However, this led me to have a look at the side of the lower carburator were the choke/throttle links are at. I find this spring that looks broken. Im now thinking this can have something to do with the problem? I have not managed to find a parts list that includes this speing, but I attach a pic below hoping for help, tips and/or guidence.

Mkolm 09-28-2020 03:06 AM

for some reason, I cant upload my picture... Working on it..

Pls send PM and I send you the picture there... I cant upload..

Sweetwater500 09-28-2020 05:31 AM

Ethanol gas probably has deteriorated your fuel lines.

Mkolm 09-28-2020 06:00 AM

Hi sweetwater,

Thanks for your input, but I find that hard to believe since I replaced all fuellines with new ones...

klyross 09-28-2020 07:26 AM

Low hours/high hours - not sure which is worse.
Had a 2000 Nissan 50 that had seeming overheating issues. Replaced water pump and thermostats,
checked fuel lines/fuel bulb, corrosion/sediment in heads, etc. Ran well much of the time, but this issue would keep returning.

Cannot comment on your spring question directly, as my mechanical skills are relatively non-existent.

Ended up purchasing a Tohatsu 50 4 stroke - works great.

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