merc 90 2stroke carb fuel problem...help

[jpn]

My problem...the first five minutes of running at 4000rpms everything is ok. then suddenly it starts to slow down inconsistently, so I put it to ilde, and give it a go and its ok again for short period of time, what chould be the probem??

I suspect cloged main jets...would that be possible?

[Nos4r2]

Is the primer bulb hard when it does it?


I suspect either an air leak in the fuel system or a dodgy (probably pinholed) diaphragm in the fuel pump.

It wouldn't reach 4000 rpm under load with clogged up mainjets.