Mariner 2 stroke 9.9HP 1999 loses power

[dirks]

After a minute full throttle engine powers down, but keeps running. What 's up?

 

[galamb]

If the compression is good I would suspect a fuel issue.

My thinking would be as follows:

You probably pump up the fuel bulb in the fuel line from the tank before you started it. That "filled up" the entire (system). Then with the motor running it has depleted a good deal of it's fuel in the system so it loses power as it "gets thirsty".

What might cause this?

A plugged vent on the gas tank. A clogged anti-siphon valve on the fuel tank. A clogged pick-up in the fuel tank. A blockage in the fuel filter (the one under the hood between the gas line connector and the fuel pump). A weak fuel pump (possibly a tear in the bladder). A clogged inlet valve on the carb. Other "cooties" in the carb. A gasket leak (carb base gasket, transfer cover etc). A blown/leaky seal (upper/lower main seals as an example).

That would be where I would start troubleshooting...