This is a J70tlesb to be exact. Just got boat last month. Motor only had 10hrs on it. Sitting since 94.. first thing i did is dumped old fuel, replaced feul filter, and pulled the drain plug on each carb bowl and pumped fresh gas threw.. used fogging oil amd got it started ran it a bit rwplaces spark plugs... ran like a top.. then i had a leaky fuel line conector on the motor side of the fuel line.. replaced it all was good.. ran it out of gas and it really fouled out the plugs.. replaced plugs and now it runs great starts right up and runs like a top.. at idle purrs i can use the idle lever thing on the forward control and will rev up and run good.. put it in the water and put some load to it and it wont rev up.. i can put it in neutral and can rev it up just fine.
I have been having difficulty with the fuel tank keeping the squeeze ball full.. if i adjust the tank vent just right the ball stays full.. im wondering if the conection on the tank is leaking and im sucking air?

Few guys at the boat house think possibly clogged jet, bad fuel tank,bad fuel pump.
Thank in advance