fowled plug

[catfish]

i have a merc 70 that has some fowling(flakes of aluminum) from the piston on the plug.<br /> i can see that it is coming from the top of the piston. the walls of the cilinder look good<br /> what will cause this? <br />

 

[12Footer]

Re: fowled plug

Bad news! Sorry to hear about that. This can be caused by a lean carb, no (or not enough) oil in the mix,an improper plug, or preignition from bad fuel. If it is an injected engine, check the system.You will need to rebuild this engine.But if you don't find the cause,it will happen again.