1989 20LG backfiring/missing

[panasonic]

Hello,

I have a 1989 20LG outboard that is missing on #2 cylinder. Have cleaned carbs, swapped coils around, checked timing and checked all the wiring. I am beginning to think it is the CDI... which is no longer available.

Does anybody have a Factory manual for this engine?

I think the 25hp is the same engine with different carbs, mine was bought in Canada (20hp)

Please help.

Thanks

[cpostis]

Hello,

I have a 1989 20LG outboard that is missing on #2 cylinder. Have cleaned carbs, swapped coils around, checked timing and checked all the wiring. I am beginning to think it is the CDI... which is no longer available.

Does anybody have a Factory manual for this engine?

I think the 25hp is the same engine with different carbs, mine was bought in Canada (20hp)

Please help.

Thanks

I could only find the owners manual. It says your motor is a 1988 model year. Here is a link.
https://www.yamaha-dealers.ca/ca/sec...6L22819930.pdf
Have you contacted https://www.yamaha-motor.ca/?

[TownsendsFJR1300]

You don't need a factory manual to do some basic testing.

IE, put a spark tester on the plug in question, confirm if there's spark or not.

Check general health with a leak down tester or at least a compression tester.

Check the spark plugs when miss firing, see if that one is wet (getting fuel ) or is dry. Check and clean all grounds and main positive line to engine (if battery is equipped)

Check all fuel filters for water / crap.

When the carbs were cleaned, did you pull ALL the jets out and visibly see thru them? Or
just spray carb cleaner? Un-less you saw light thru them, they ain't clean...

Is the engine new to you, or have been sitting for awhile?

[99yam40]

Check fuel pump also.
my guess is this motor has 2 cylinders

if it is leaking it could dump fuel into the crankcase and cause a too rich condition to the cylinder that runs the pulse to the pump

[panasonic]

How would you suggest I check the pump? I had the carbs off twice to clean, inspect and rebuilt the pump already. I have another thread started on this issue if you would like to review it and give your opinion. Probably should delete this thread if that is possible.

Thanks for your input