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Tohatsu 15hp 4 stroke starting problems

L

Liquid Steel

New member
Hi all, new here, sorry but can't find a Tohatsu section. I need help :(. I have a 15hp 4 stroke Tohatsu, went under during a flood (freshwater). Now serviced with carb cleaned, plugs, oil etc. Compression fine, gearbox fine. Only major non-start issue was defunk dead man, so replaced. Now, I had it running sweet in dry dock, took the motor back to the boat and wouldn't start, (car journey down the motorway). The only thing I could do to get it running was partially cover the air inlet with my hand, it then ran sweet. Does anyone think they have a solution, ie. auto-choke unit. Sorry if it's not Mercury related but I'm hoping this could be general 4 stroke issue. Thanks.
 
You have a fuel delivery issue . Are you running with clean tank and lines,new fuel in clean tank ? Is primer bulb firming up before startup? Are you using proper starting procedure? Does your engine have a fuel primer or a choke assembly? If you have filters check them.Does your boat have a fuel/water separator on board? Water still in fuel system?
 
johnnygjr said:
You have a fuel delivery issue . Are you running with clean tank and lines,new fuel in clean tank ? Is primer bulb firming up before startup? Are you using proper starting procedure? Does your engine have a fuel primer or a choke assembly? If you have filters check them.Does your boat have a fuel/water separator on board? Water still in fuel system?
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Hi Johnny, thank you for your help. Clean tank & new fuel. The primer firms up after 3 or 4 squeezes, if I loosen the carb drain the primer will force the fuel out of the carb. The choke is the electronic plunger type on top of the carb, I have no meter to test it unfortunately. There appears to be no type of inline filter on the engine. The fuel line enters a small unit on the front of the power head then exits to the carb, I've stripped/cleaned this. The motor ran sweet in dry dock, I tested it several times before making the journey to the boat, then when mounted it failed immediately (unless I used the hand over air intake method). This is really all I can tell you at the moment, baffled. :(:(
 
So when your restrict the "air in" it runs fine.

That indicates that it's probably sucking air from "somewhere it shouldn't be".

I would re-inspect any gasket or seal connected to the crankcase - somewhere it's sucking in air or blowing out air/fuel.
 
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