Hello guys,

I just bought a 94 303 Formula with 502's. It sat for 2 years. When putting it on plane, there has been some small backfires and then evens out and jumps on plane. Last night, a small pop turned large backfire and it lost all power. Now the guages wont even work on that starboard side. No power at all. I checked battery, main pigtail, etc. Is there a cutoff that would be tripped by a backfire? Any ideas would be helpful.

There is a fuse by the starter that could have blown.
As for the original issues, it could be any of a number of things or a combination of several.

It sounds like the purple wire to the coil is shorted. If it stays dead shorted long enough it blows an inline fuse that provides power to the ignition switch. Once this 20amp fuse blows you have no gages, no crank, ect. Find this fuse and if blown replace it. You may need to lift the purple wires from the + side of the coil to get the fuse to not keep blowing until you can locate the short. I just went through this and the short was in the excite wire that runs from the + side of the coil to the alternator. The ignition wire runs through the kill switches too.