Baffles by fouling plug on Pro

[Action Jack]

The motor is a 1993 Yamaha Pro V 150
P150TLRQ 2 stroke V6

Last year it started running rough. I noticed it would foul the plug on the lowest clyinder. I would put a new plug in and it would run great for a few trips till it got fouled again. We tested the coils and found them to be all good. We even pulled the motor off and changed the crank seal, figuring cause it was the lowest cylinder that maybe it was sucking up oil. I 'm not sure where to go from here. Could it be carbs? There are three of them and I figure both cylinders would be over fueled if it was that carb. Can anyone shed some light on this fouling plug dilemma pls?
Thanks Jack

 

[rodbolt]

Re: Baffles by fouling plug on Pro

could be a lift pump diaphram leaking if its fuel fouled, could be an inline oil check valve if its oil fouled. and last but not least it could be a defective recirc check valve thats doesnt even get mentioned in the service manual but its there.
6 of them are there actually, one for each cylinder.
there is one pressed in the block for each cylinder with a gray hose attached.
use a syringe filled with alcohol and fluid should flow one way and not the other.