carb problems

[moonwalker]

My 1987 30hp yamaha runs like a 5hp wizard outboard. Pushes my 14ft jon boat pretty slow unless I pull the choke about half way out, this helps some. Have removed and cleaned the carbs, is there anything else that could be causing this problem? Thanks for your help

[CatCam]

Are you sure you are firing on all cylinders? I had a 40 HP Yamaha that ran like a 26.6 HP because it was only firing on 2 cylinders.

If you have cleaned the carbs I would check and make sure the tank is good (holding pressure, vent, etc), squeeze prime ball is good and then progress to the fuel pump.

[moonwalker]

all cylinders fire. I am not sure about the new VENTLESS gas tank, not sure how it is suppose to work- bulb never seems to pump up hard but motor starts on first pull

[99yam40]

bulb never seems to pump up hard

need to find out why
bad fuel pump or air leak are my guesses

[boats.net]

If runs better with choke then need to remove and clean carbs.