1999 Mercury 5 hp 2 stroke- Low power at full throttle- Fuel issue? Carb?

[UnkleFidel]

Brand New here so thank you all in advance. Forums have worked wonders for me in the past and the sharing of knowledge is paramount to all us wannabe DIY'ers.

So my neighbor got a little john boat with a 1999 merc 5hp 2 stroke. I did a clean job on the carb and got it to fire up and hold an idle after adding some good gas. Took it out for a several tests and all I can get is 3/4 knots out of her. She sounds bogged down, like she is not getting good gas. I tried going back and forth from external to internal fuel tank. Pinched the lines, they seem to be flowing, spilling out easily right near the carb intake when detached. I've pumped the ball to add pressure, released the vent on the internal tank. Now it seems over my head. Throttle is wide open. Revs up high in neutral, not in gear.
Any ideas? Next step in the test Process?

Thanks again. I really appreciate any input.

 

[Bondo]

I did a clean job on the carb

Ayuh,.... Sounds like it needs a full blown Rebuild,.....

 

[Sea Rider]

That model should have a dual fuel tank, interior and exterior, right ? If so, check a small one way flow internal fuel mesh filter located after fuel ****, remove it and blow air till air passes with no restriction. Is your fuel line grey or black ?

Happy Boating

 

[UnkleFidel]

Thank you guys for the reply. You are correct it has both an internal fuel tank as well as an external line. The fuel filters are clean and allowing gas to come through easy. The lines are black.

A full blown rebuild is do-able. The local store here wants about $130 for a kit. That seems awful high doesn't it?

A friend suggested the spark plug. The engine starts much easier now but still won't rev while in gear.

I must emphasize that the engine rev's in neutral, rev's as high as you want it to. When in gear, it sounds bogged down. If there are any other ideas out there I would like to hear them before I spend $130 on a carb kit.