5.0 omc runs about three minutes under power then dies, runs great at the dock

[bobbyone]

88 bayliner 5.0 omc runs great at the dock or in the driveway but under power it runs about three minutes?????
changed coil, points,condensor fuel pump gas filters fuel line and pick up tube, it will then run off of idle fine back to dock or if I run it for five at an idle it will run again for three

 

[Howard Sterndrive]

Re: 5.0 omc runs about three minutes under power then dies, runs great at the dock

you are losing one of the three things an engine needs to run:
-fuel
-properly timed spark
-air

so when it shuts off, look down the carb throat while pumping the throttle to see if there is gas
then check for spark
air is unlikely but if you have exhaust leaks that can make for bad air

after that basic stuff, pull the plugs and see if there is water in the cylinders and do a compression test