I have a 94' 225 Yamaha Carbed engine. Bought boat last year and had no problems. This year got a hesiatation when trying to accelerate. Mechanic stated needed a carb job and tune up(New Plugs at this time). After carb job engine would not get over 700 rpms without dying. Mechanic said it had fouled a plug. Replaced one of the new plugs took out and still would not run over 700. We replaced another plug. Mechanic met me at lake and we ran the boat fine and then it started the same thing by not getting over 700 rpms. He stated these big block V6's were bad to wet foul plugs and he trimmed motor and idled it up until carbs were lean on fuel. Trimmed motor down and took off and ran fine. I ran it around the Lake for twenty minutes and had no problems.<br /><br />I have ran the motor once since meeting the mechanic and made sure that motor was trimmed up when idleing to keep from loading the carbs. Ran it in the day on a lake I knew well and mainly ran full out. Took it out this weekend and idled it around trying to graph some stripers. When I decided to head back to ramp it was dark and I was on unfamiliar waters. Kept the boat at around 35 mph and had to keep it trimmed down a good bit to keep it from porpoising. Stopped once to get my bearings and then engine would not get over 2700 Rpms. Never could get it on plane. I was about 2 miles from ramp and I tryed all of the ways that the mechanic did to get it to run right. All to no avail. Finally stopped in water and replaced all plugs with a set that I started carrying because of my recent problems. Started ran fine all the way to ramp and no problems. My Boat is 20'6" inches long and will porpoise if I go slow with engine trimmed up. I bought boat in spring 2001 and ran it all 1st year with no problems. Now almost everytime I take it out if I try to idle around alot it fouls a plug. When I pulled plugs there was oil around threads and when I pulled each plug looked wet and had a little oil enough that I wiped it with a rag from each thread hole.. All plug were a little black and the middle plug on the passenger side had a little build up. Are Big Block V6 engines bad to foul plugs? Why is this engine continually fouling the plugs? What would cause this to happen all of a sudden?
