87 johns ob 150GT runs 1 day not the next

[aubu]

Has an intermitting problem.Runs great 1 day, next day falls on its face. No power when underload. Next day will run great again. Had 2 lake mechanics and one inland work on it. Plugs replaced,plugs wires replaced,stator replaced,1 power pac replaced,new oil tank & oil pick up, fuel pump replaced 2 yrs ago. take it out of gear revs up 4000 rpms<br /><br />1987 Johnson 150GT man7572376

 

[clanton]

Re: 87 johns ob 150GT runs 1 day not the next

Check the ignition system with peak reading meter, boat in water engine running loaded, connect meter leads to ignition coils checking each cylinder, all readings should be same about 130/150 volts. Check carb gasket on top of carb, if this is orginal gasket, it may be sucked into the carb passage, later carb kits had inproved gasket. Check diode in packs. Check flywheel magnets. A quick stator check is run engine/boat in water full throttle 5000 rpms, touch trim up button for 2/3 seconds, if RPMs drop 3/400 rpms the stator is bad.