Im having 115hp 4 cyl inline carb mercury...
- problem : difficult to start and very unconsisten idle when it started by fast idle method.
- job done : clean up carb, adjust timing to 1 degree ATDC for idle and clean up fuel filter.
- Iam using fresh external unleaded fuel.
- spark plug is new according recomendation and there is no problem for ignition sys.
- carb air bypass already adjusted to standard at 1 1/4 turn.
- any advice from forum member ASAP.

Possible the fuel primer, check it as per service manual. Does it start ok after engine warms up?

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thanks, after further checking, ifound that fuel pump coldge with small particle from inner layer old type quicksilver fuel line. what i have to do is to change fuel pump diapraghm kit.