1997 C40 runs WOT 30 min. drops to idle

[briansdenny]

My 40 HP 2-stroke clips along great for 30 minutes and then drops down to 600 RPM. I let it sit for an hour and same thing occurs. Any ideas?

[exeter27]

My hunch is that your fuel tank eventually develops enough vacuum that the engine is starved of fuel. Either your cap vent isn't opened or is partially clogged. Letting it sit for a while restores atmospheric pressure and gas again flows. Like I said, a hunch and an easy check.

[briansdenny]

***, never thought of that but is plausible...thanks, will try.