mercury classic 50 running issues

[cgallego73]

I have a 1989 mercury classic 50 that will start up and run great for about 5-10 minutes then the motor shuts off and quits running. It will restart but usually in about an hour or so, its never the same amount of time. I checked plugs and there doesn't seem to be any spark for that hour or so. Any ideas what could cause this issue? It has had the stator and cdi replaced a few years ago but ? thanks for any help

 

[mlbinseattle]

I'd have to say there was an intermittent connection that's opening after it gets so hot. Is the problem with no spark common to all cylinders or only one? Could be a faulty CDI or stator. Again, is this happening on all cylinders? Inspect all your wiring to ensure good connections and continuity. Additionally, inspect all your ground wires. Troubleshoot when the problem is happening to see if any readings have gone out of spec. CDI Electronics has a troubleshooting guide: http://issuu.com/cdielectronics/docs/practical_ouboard_ignition_troubles Also, you might want to get the service manual for that engine. IMO, it's heat related, and being an ex-Navy electronics tech, I've seen my fair share of heat related intermittent connection issues.