[ray j]

1980 75hp Evinrude runs just fine on the hill but once under load just bogs down as if not getting gas. brought home and checked carbs. all looked clean.took out bottom screw on all three carbs and they were full of clean gas.just replaced plugs. i just bought new fuel tank and noticed i had not opened vent all they way. could this be the problem or could it be electrical in nature?

[OBJ]

Welcome Ray!Is this engine new to you? If it's new to you, had it been setting long before you got it?Always keep the fuel tank vent wide open. Although you did not have the vent wide open, I do not think this is the cause of the engine not making WOT.Have any idea when the carbs were last overhauled? Reason being, you really can't tell what's in the bowl without taking the carb apart.If the engine is new to you, take the time to do some tests. Compression and spark tests' are a must. Check the throttle plates are opening and closing fully and at the same time....you'll need to take the carb cover off to do this.Check your fuel lines are still pliable and good. Hard fuel lines can suck air at connection points.If you have no idea when the carbs have been last overhauled, I would recommend it. A lean running looper like yours could in time scuff the cylinder walls.Make sure the choke plate is opening all the way when the solenoid is deenergized.A service manual would help you a lot. OEM's are preferred because of the specific info they give on a given engine.Give us a little history on the engine and we'll see what we can do.