Need advise for Yamaha 150 problem

I recently bought a 1998 striper 2600 WA with two 1998 Yamaha 150 Saltwater Series. The boat was not used for more than one year. Both engines start fine after choking and idle at 700 rpm. The problem I have is with the port engine. It will not exceed 2100 rpm by itself. If I open the throttle completely it drowns and sometimes dies. I have to keep the startboard engine reved up to more than 3500 rpm for the port engine to increase rpms. In that scenario it has gone up to 3300 rmps but if I cut the throttles on the starboard (good) engine, the port engine dies and slows to less than 2100 rpm and looses power. Both fuel primer bulbs are new, I emptied the gas tank and filled it with new gas. New fuel filters and new fuel separators. The fuel line from the separators to the engines are new as well as the spark plugs and thermostats. I replace the fuel pumps in the starboard (good) engine. I noticed that when I pressed the fuel primer bulb, it would not become as hard in the engine with the problem when compared to the good engine.

I plan to change the fuel pumps on the port (bad) engine, as well as change the carburator kits. Also I plan to replace the fuel line from the tank to the separator to that engine (approximately 12 ft). Any ideas on what could be the cause. My first approach is a fuel issue. Thanks in advance for any advise.

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I forgot, If I rev up the engine in neutral it will rev up all the way until the rpm limiter kicks in.

[jb123]

DONT rev up that hi...

i ASSUME the starboard motor running at a higher rpm allows port to run higher than it would without the help.

because it was not used for a year....it sounds likely to be a carb issue...

you can try to choke port while running...if it helps then its carbs.

try an auxillary tank on the problem motor...different tank, ball and hose, hooked into the motor filter..,,,see if that produces any change.

you have 2 totally seperate fuel lines, from tank to motors?

again most likely you have clogged carbs and the would need to be cleaned.

Thanks for the advise. Yesterday I removed the carburators. The lowest one had some gunk and dirt in the float bowl. There was dirt in the main jets. The top and middle carburator had some dirt inside but not as bad as the bottom one. I installed the rebuilt kits on each carb. I adjusted the floats to the 0.62 inches specification in the manual. I found them set lower in the bowl. I could not remove the big screw on top of the pilot needles. The kit has new ones but I could not remove any of them. Any ideas on how to remove them? I did spray a lot of carburator cleaner throught the needle opening and made sure that the spray holes in the carburator throat were clean.

I have one single 137 gallon tank but each motor has independent fuel pickups, lines and primer bulbs.

[jb123]

those can be tough, use the widest screwdriver, and on a good solid flat surface, tap screwdriver with hammer. you may want to ask somebody to hold the carb for you while you do this.

Thanks, I'll try them on Saturday and will let you know the results.