77 mercury 402 starting problems

[Sulerich76]

I need help identifying what’s keeping my 402 from firing, I had it looked at and was told I had no spark but after taking home and trying myself it started. Then a couple days later nothing again! Have had this trouble all summer just not sure what the cause could be?

 

[racerone]

They had issues with wiring in the mid / late 1970's-------Inspect all wires on the motor.