What would make only cylinder 7 overload full on sparkplug
If it is miss firing on #7... the spark plug, coil on plug or fuel injector will likely be at fault. If the #7 spark plug is fouled... it could be a stuck open fuel injector, bad valve guide seal or piston ring or cylinder issue. Could also be a head gasket issue. The question you asked is very vague, please be more specific and supply more info.
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