Wondering if somebody nay have some suggestions.
My Merc 90 2 stroke has developed an odd problem. The logical thing is to take it to the service agent - except;
a) the motor is in Vanuatu and I have had some experience of the local agent. If it was Firmans Marine (my NZ agent) no problem.
b) the motor is only doing this after extended running. It would likely run perfect in a test tank all day long.
I can go 20k out, fish 3-5 hrs then run 20k back home. A number of times lately 3-4k from home (virtually same spot each time) it starts dropping revs and surging. My guess was a fuel starvation problem. I have a filter/water separator between the motor and fuel tank. Changed that. Replaced some fuel line and re kitted the pump. Next run I thought problem solved. Perfect. Nope. Back again. The fuel bulb has pressure when this happens - squeezing it doesn't alter anything.
I have a spare virgin coil/HT lead. Just fitted it to one cylinder - will swap over til done all 3 if problem persists. Checked tank breather vent, and cracked the filler cap. No change.
In the back of my mind I wonder about a crack in the block/head. But seems weird to be so repeatable. Once running first time, runs/starts perfect all day. Until 3-4k from home. I wonder about fuel level in tank - never been an issue before - but will add fuel to tank next time. Not sure if related - but has become a bit of a pig for first start of the day - then purrs/starts like a kitten all day long - until 3-4 k from home.
Anyone got any suggestions where else to look?
Thanks
Alan