Boat only idles after running fine for 20 minutes

[MalibuJerry]

My 1996 Malibu with V-8 inboard starts fine and runs fine for about 20 minutes. It then bogs down and dies. Engine starts up fine but will only run at idle speed after it bogs down. Water temp. is normal. after letting to boat sit for an hour the same process will repeat. Boat had tune up this spring with new plugs, distributor cap etc. Any suggestions for a fix. Saw similar problems on forms but never a clear fix?

 

[nola mike]

My 1996 Malibu with V-8 inboard starts fine and runs fine for about 20 minutes. It then bogs down and dies. Engine starts up fine but will only run at idle speed after it bogs down. Water temp. is normal. after letting to boat sit for an hour the same process will repeat. Boat had tune up this spring with new plugs, distributor cap etc. Any suggestions for a fix. Saw similar problems on forms but never a clear fix?

First try unscrewing your gas cap when it happens. If you hear a hiss then your vent is plugged. Next start chasing fuel problems. Check/replace your fuel filters. Then check fuel pressure, rebuild the carb...

 

[achris]

First try unscrewing your gas cap when it happens. If you hear a hiss then your vent is plugged. Next start chasing fuel problems. Check/replace your fuel filters. Then check fuel pressure, rebuild the carb...

This....