Yamaha #1 Cylinder Misfire or no fire

[Nowisthetime]

I have a 2003 Yamaha F90TLRB four stroke outboard. It began running rough three weeks ago after seasonal launch. Changed plugs and the plug in #1 cyclinder looked like it was brand new. Other three cylinder plugs were light brown which is normal. Replaced the wires. Ran the engine - still ran rough - pulled plug one and it was wet. Switched coil packs, went for another ride, still ran rough, low rpm. Pulled plug one and it was wet with no discoloration of the neutral. Engine seems to idle okay - meaning it doesn't stall out - but acceleration is weak and max rpm is not reached. Am using 89 octane non-ethanol gasoline. Any suggestions???

[waltdiggity]

check compression

[Nowisthetime]

Yamaha F90TLRB

Compression:

Cyl #1 = 155
Cyl #2 = 145
Cly #3 = 135
Cly #4 = 125

Clylinder #1 is the cylinder with the plug that appears wet when pulled out and is the cylinder misfiring.

After compression test and plugs reinstalled, motor operated okay for about 30 minutes then developed loss of power. At full throttle 3,000 rpm and speed under 10 mph.

[99yam40]

Motor needs the proper fuel/air ratio. compression, and spark at the proper time to fire the cylinder.
Change plugs too see it that helps, check to see if it is sparking properly, if it is the you have a fuel issue.could be too much fuel or too little
If the cylinder is running lean you will hurt the piston if you keep running it that way.

[Nowisthetime]

Yamaha F90TLRB

Have replaced the plugs twice since May 20. Always the same. Cylinder #1 is wet the other 3 looked the same - light grey. Although, in pulling the plugs for the compression test, cylinder #2 looked carbon fouled. All fuel used is ethanol free - or so it is advertised. Fuel filter looks clean and no water in the setiment bowl. As for electrical, when the misfire first started replaced the plugs, the wires and switched coils. Still the same result.

[boats.net]

Possible need carbs cleaned, possible vacumn leak on intake or need carbs synchronized.

[Nowisthetime]

Yamaha F90TLRB Engine Misfire/No Fire

Four carburators were removed and disassembled. No visible signs of plugged jets, dirt, etc. Upon reassembly, it was noticed that the float on carburator 1was not at the same level as the other 3. After further examination, it was found that the needle value was 1/16" longer on carburator 1. A new needle valve and seat were installed. Carburators reinstalled, adjusted and balanced. Problem solved. Since the motor is 7 years old and this was not a problem for all of those years there was something in the last two years the caused the part to fail. The needle itself is a sleave within a sleave and the inner sleave slide out the 1/16". We could not get the two pieces back together.