Engine Stalling

1985 230 Chevy block Merc. Starts no issue. Stalls after 5-8 minutes at full or close throttle. Re-starts, runs at low rpms fine, will run again at full throttle for another 5 minutes or so before sputtering, backfiring, and stalling again. Thought there was water in the fuel issues, emptied water separator, put in dry gas and went through the full throttle stalling process 5-6 times over a few hours trying to burn the gas out. Removed the fuel line hose from the gas tank, took off the nipple connector to see if the stop/gap ball was in there (it wasn't), removed the pipe from the tank to see if the screen was clogged (no), proceeded to break off the top connector piece when putting it back on (aluminum breaks easily). I've yet to check the filter where the line enters the carb, but it seems somewhere the gas is getting choked. Any thoughts?

Re: Engine Stalling

Try running it off a remote tank. It has a fuel pump so try using an outboard tank plumbed to the suction side if your sure it's a fuel delivery issue. Still Stalls? Check for spark when it quits. Coils sometimes heat up under load and fail. Not much info for id of your drive package. Points? Thunderbolt? Something else? Do a full tuneup, etc. Get a manual. Need a serial number for that I believe. This a new issue or has the boat been sitting? Need a little more info.

Re: Engine Stalling

Could be as simple as a plugged vent.
Might try this test, then you will know what to start looking for.
http://forums.iboats.com/showthread.php?t=167561

Re: Engine Stalling

sometimes the screen gets clogged momentarily when the sucking is too strong at high rpm. when the engine stops the crasp fells down and when inspecting it you think that the problem can't be the tank. So trying an external tank directly to the pump will tell you much.