15hp dead on low end

[smartwork]

My dad purchased a boat last year with a Merc 15hp 4-stroke on it that is almost brand new and ran like a fine sewing machine. Toward the end of last summer, the low end speed just died and it pretty much refused to run normally. The engine would start and run with the choke on. High speed worked about like normal.

Thoughts are not enough fuel or too much air. Thinking it possibly was trash in the carb's low speed draw, we checked and flushed but we've not located anything. Other things checked:

• replaced gas
• checked all lines for breaks / cracks / connections
• flushed out carb
• ensured carb was mounted tightly
• checked fuel filter

We even tried drawing fuel straight from another container to eliminate the variable of the fuel line, bulb, and tank. We may have seen a little improvement, but it' still not right.

Any thoughts on additional areas to check? It was somewhat of a sudden issue, so it acted like blockage, but we've not located a solution yet.

Thanks!

 

[TOHATSU GURU]

Re: 15hp dead on low end

Clean the carb, after disassembly, by dipping it in a one gallon pail of carburetor cleaner for three hours.