Old Merc 80 HP won't start and backfires

[aaronispro1]

Bought a boat and motor for cheap. Had no spark at first, (coil fuse?) Anyhow bypassed it with a shot piece of wire. Got it to spark. But now put fuel to it and..... Not starting.... And BANG! Any help would be greatly appreciated

 

[GA_Boater]

Welcome aboard.

Old Merc 80 doesn't help us much. What is the serial number?

 

[aaronispro1]

Figured it out. Some dummy had the coils hooked up backwards. But next question... My serial number does not come up with anything on Mercs site. It's 1664900. Tagged above and between transom clamps