My murray caught on fire last year from loose fuel line, but not badly damaged. I have replaced all burnt parts (fuel line, fuel and air filter, belts, muffler, and plug). I inspected all wires and found only 2 burnt completely: a yellow wire from start switch/coil, and black wire from sp. Plug. Both wires were grounded on side of engine near carb. I cut the wires back to good wire and grounded them on other bolts. It cranks good, but no spark. Fuse looks good. Do these wires complete a circuit and need to be grounded together again?

If you have the spark plug wire grounded, it will not fire.