Stupid question...

[kwaziwampo]

Just started sailing, and this may be a stupid question...
2-stroke Nissan 3.5 motor (1992). Fires up fine. Runs in neutral fine. Goes forward fine...for about 5 minutes. Then it slowly decreases speed on it's own until it dies. Then...when I restart, it dies quicker and quicker.
I've got the manual...gas mix is correct. Starting procedure is correct. Warming up is being done...letting air in is done...etc.
Seems like it's not getting enough air. It's spitting out water as it should, so it's no overheating.
Thoughts?

[Fishspearit]

possibly fuel starvation. Check that the vent is open and clear, fuel filter is clean and unobstructed.

[Zephyr's Aura]

Check to make sure your fuel cap vent is open and not plugged up. I assume that is what you meant by letting air in. Next check the fuel line to make sure it's not collapsing.

Best of luck!

[kwaziwampo]

Cool-thanks to both of you-I'll check those items out.

[Therapy]

I had a vent that when unscrewed was not really open.
Maybe you do too.
Second vote is filter.