tohatsu B38B runs rough

c.carr

Recruit
Joined
Oct 4, 2010
Messages
3
I picked up a tohatsu 25hp B38B for $75. It started right up after sitting for 8 years, but is idling rough and misses occasionally when the rpms go up. The plugs are new but wet when I pull them. I'm just running it in a barrel and can't run it in gear or the water just goes everywhere so I can't really put a load on it. Just wondering where to start as I don't think I can find any parts for it.
 

TOHATSU GURU

Admiral
Joined
Jul 22, 2004
Messages
6,164
Re: tohatsu B38B runs rough

The engine is older than dirt and parts have not been available for it for 25 years.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: tohatsu B38B runs rough

Start by cleaning all gas paths from tank to carb including a long carb cleaner deep soak.

Happy Boating
 

c.carr

Recruit
Joined
Oct 4, 2010
Messages
3
Re: tohatsu B38B runs rough

Thanks. Yeah, I know its old, but it was cheap and is in really nice shape, at least concerning looks. Paint's all good and everything. Its probably only been in fresh water and by the looks has been sitting around for years. Would it do any good to soak the carb w/o disassembling it? I'm afraid of not having new gaskets. I started with a 25:1 mix and tried 32:1 with no difference in performance. Any idea of the correct fuel mix?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: tohatsu B38B runs rough

Sitting for such long time period, definitely must disassemble complete carb for a perfect clean, is it o'ring or plain cardboard gasket type. If cardboard type can make one yourself tracing old one with appropriate cutting knives. Mix should be as usual 50.1 But better ask Tohatsu.

If it's in really good shape as stated, you can have a near vintage engine performing excellent as in the good old boating days at a very low purchase & maintenance cost.

Happy Boating
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
Re: tohatsu B38B runs rough

Thanks. Yeah, I know its old, but it was cheap and is in really nice shape, at least concerning looks. Paint's all good and everything. Its probably only been in fresh water and by the looks has been sitting around for years. Would it do any good to soak the carb w/o disassembling it? I'm afraid of not having new gaskets. I started with a 25:1 mix and tried 32:1 with no difference in performance. Any idea of the correct fuel mix?

The carb must be disassembled for a decent cleaning. if you soak it in Tyme or similar dip without disassembly, anything rubber will melt and you will have x pounds of scrap metal.
 
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