1975 Mercury 65 hp no spark

[endurance]

Got this motor and it use to start right up even
after siting awhile. I noticed when i had it runing
it would just shut off then i would try again and it started. Now it hAs no spark. Any help on this would
be great. Thank you

 

[Maxz695]

Re: 1975 Mercury 65 hp no spark

It could be grounding wires kill switch, could be stator not sending current. It could be the capacitor in the switchbox may have blown. I would start by going over the electrical system and looking for bare sopts that may have grounded out, loose connections, and possibly disconnecting the pigtail to eliminate throttle key switch, saftey kill, neutral shift switch also which will not let the engine start in any gear but neutral if your shifter has this as a saftey features.

 

[CharlieB]

Re: 1975 Mercury 65 hp no spark

Distributor ignition?

One wire to the Ignition module should always have 12 V, another should be switched 12 V with the key turned On. Both wires must have 12 V for the module to function.

Search the forums for Ignition Troubleshooting Guide and you should find the complete Troubleshooting guide from CDI Electronics which details every step very simple testing directions for determining exactly what any ignition problem is.

 

[endurance]

Re: 1975 Mercury 65 hp no spark

Thank you both. Rear Admiral thanks for the cdi heads up
havent checked it yet. Question I have 12v constant on red wire amd 12 volts on white wire when key is turned. Do you think the switch bbox is bad

 

[mercurymang]

Re: 1975 Mercury 65 hp no spark

Thank you both. Rear Admiral thanks for the cdi heads up
havent checked it yet. Question I have 12v constant on red wire amd 12 volts on white wire when key is turned. Do you think the switch bbox is bad

Here's a link to the schematic. I'll be following as I have the exact same motor you have.

 

[CharlieB]

Re: 1975 Mercury 65 hp no spark

The module may yet be good, you need to test it correctly to determine if it is the module or the trigger.

Complete test details are found in the following Ignition Troubleshooting Guide, simply look up your specifc ignition and follow the directions.

CDI Electronics Practical Outboard Ignition Troubleshooting

See the bottom section on page 66

 

[bunnybuster]

Having the same problem on my mercury 650
no spark...any help?