40 hp not revving

[trx565]

i have a early 90s mercury 40 hp 2 stroke pull start with tiller. engine starts easy and idile fine but when it is under a load the engine sounds like it is starving for fuel and wont rev. it has a prime button and if i push it repeatively it will rev up. does the fuel pumps on these motors get weak or do they just go out? or does it sound like something else.thanks

 

[fastjeff]

Open the idle mixture screw (CCW) about 1/2 turn and see if that helps. All of my many 2 stroke devices need to be enrichened since ethanol gas came along.

Jeff