I have a Tohatsu 6HP 4 stroke, 2009 that is generally reliable but often has slow running problems after being stored for the winter. It starts first pull but will not settle down to slow running when warmed up and the choke is pushed in.
The mechanic who services it for me recently gave me some interesting insights. Apparently the fuel jet on modern 4 stroke outboard carburettors is very small diameter and easily blocked by gummy residue from stale fuel or, of course, rubbish in the petrol. This leads to fuel starvation when the choke is pushed in. The jet hole is too small to rod through with even fine wire, so the mechanic has to remove it and clean it using an ultrasonic tank and filled with his magic secret fluid, not a task I would do myself.
Reasonably frequent use of the engine with fresh fuel keeps it clear. But preventing fuel blockage over winter is difficult. Draining the fuel at the end of a season may not clear old fuel from the jet, even if the carburettor is drained. So the best bet is drain the fuel at the end of the season, flush the cooling system through with fresh water etc but then get it serviced in the spring.
Any other ideas - excepting buy an old Seagull or row?
Matthew
BR20 Gladys