Boat Engine just stops while cruising

[Johnny7]

Hello Folks:

I not sure you can help me but I have a vexing electrical problem with my boat. The boat is a 1986 5.7 L Mercruiser 260 HP. Up until this boating season she ran ok. Last year I had a mechanic install a new Distributor and module. Boat ran fine. This year put her in the water and had brought her up to cruising speed she ran perfect for about 30 minutes and then stopped as if someone turned off the ignition key. No sputter pop or hisss just full engine off. I quickly restarted and was just to get back up on step and she did it again. Started her again and she ran fine but only at low speed. At the Dock the mechanic could not find a problem but suspected a faulty ignition switch which we replaced. Took her out with the mechanic and she did the same thing. We got her started and the mechanic ran a jumper wire from the positive pole on battery to the positive screw on coil. She ran like a charm and did not quit at all. We could not pinpoint the issue, so when I take her out I put on the jumper between the coil and the battery and she runs fine every time. Any ideas what might be wrong? Any help would be greatly appreciated.

Thank you
johnny7

 

[glenn property of pam]

Have you replaced the coil. If so is it a internal or external resistor type. If its a external then you should test the resistor wire to see if its with in spec.

 

[ssobol]

Check for pushed pins in the engine wiring harness(es). A long time ago a friend had a boat that would perform similarly to what you describe. We'd be cruising along and the motor would just quit. Sometimes it would start up again right away and sometimes it would take awhile to get the motor going again. We eventually found that where the main harness connected to the engine one of the pins was pushed back a bit and didn't stick out a far as the others. Various vibrations and temperature changes could cause the connection to be interrupted causing the motor to quit.

 

[Johnny7]

Thanks to both of you for your suggestions will test my coil and check out the harness at the engine.