I am dead in the water right now. I was cruising and my engine (merc. 502 carbed) sputtered 2-3 times and quit. It felt like the carb was loading up and my plugs were fouled. At first I pulled the plugs because it seemed like they were fouled. My #7 plug was completely fried. I replaced all the plugs and did not fire at all. Pulled one plug and rolled engine over and no spark. Put test light on coil and I have power to coil. Put a used coil I had off another 502 and still no spark. Where do I go from here, and why did this plug burn like it did. All the rest of plugs were fouled but still in good shape.

What kind of ignition?

I had a plug do that from a lean condition on a blower motor. Bad octane.

It is a MSD coil and distributor, both are only a couple months old.

It is possible the coil to distributor wire is broken or bad.

How are you checking for spark? If you have or can borrow a working timing light it will help diagnose this, you can see if the distributor is feeding the plug wires with it.

Also, I am assuming you are running the stand alone MSD distributor, check to make sure it is still plugged in and properly grounded.

Bad plugs/wires/coils can wipe out the electrical pick-ups in distributors. They don't always do it, but it happens.

I pulled a plug, touched it to the block while a buddy turned the engine over and no spark. I will check the dist and wire.

check dist have some one crank mtr with cap off make sure rotor is turning you might of ate a dist gear,

take a test light to the - side of the coil attach other end to pos on batt crank mtr the test light should flash to show pulse to coil if not you have a bad pick up

A bad MSD, unheard of!
BTW cranking an engine without the plugs hooked up, or grounded, can fry some ignitions.
Gary

What kind of Champion plug is that?

It looks pretty mangled, is it a split fire? If so, I wouldn't use them in a boat. Use a race plug.

If you are running MSD's ready-to-run distributor, it is probably a bad module which is not customer serviceable.
Send the distributor back to them and they will replace it with a 'reman' replacement for around $75.00. Be sure to send in the cap and rotor and they get replaced in the process. BTDT