1986 mercrusier 4.3. New ignition module, pick-up sensor, cap, rotor, plugs, wires. It cranks over and has a nice spark, just wont fire. All I get it back fires out of the carb and exhaust. Started with timing a 0 degress and moved it clockwise and counter clock wise and no change. any ideas? also i tripled checked the firing order and it is correct
