Boat is 1986 Cobalt with 5.7L Mercruiser Alpha 1. It starts fine when cold. After running 5-10 minutes at 2500-3000, RPM drops, won't take throttle, eventually stops. I can't restart immediately, but can start after a few minutes. Then, won't take throttle, have to run just above idle to get back to dock. Next day, same scenario.
It ran fine last fall. Was winterized by marina. Problem showed up to minor extent when I first used it this spring. Now it's bad.
The first thing I did was to change the fuel filter (and also clean the screen at the carb, which had only a little crud). No effect.
It seems to be temperature related, although the engine does not run hot. OK when cold for few minutes, then dies, won't restart until engine cools off.
I suspect something internal, like a crack in block or intake manifold. I can visualize a scenario where a small crack, especially in manifold, opens up when warm allowing water to get in.
Help!
It ran fine last fall. Was winterized by marina. Problem showed up to minor extent when I first used it this spring. Now it's bad.
The first thing I did was to change the fuel filter (and also clean the screen at the carb, which had only a little crud). No effect.
It seems to be temperature related, although the engine does not run hot. OK when cold for few minutes, then dies, won't restart until engine cools off.
I suspect something internal, like a crack in block or intake manifold. I can visualize a scenario where a small crack, especially in manifold, opens up when warm allowing water to get in.
Help!