1970 Mercury 800: Will start, but shuts off when key is released.

fordtrck1955

Recruit
Joined
Jul 30, 2011
Messages
1
Just bought this boat a few weeks ago. Someone had trashed the old ignition switch in the Mercontrol box. I bought a new Mercury switch (pn. 54211), and installed it correctly. I've been through all the wiring several times to make sure, and even compared to another Mercontrol box that I had. I had already removed and cleaned the carbs while waiting on the switch to get here. Now, when I start it, it will crank and start fine, but when i release the switch to the RUN position, it shuts off. If I hold it in the start position after the starter had kicked out, it'll run fine. Took the Mercontrol box apart again, and checked the wiring 3 more times. Checked the continuity of the switch per the wiring diagrams, but found nothing. Any ideas would be greatly appreciated. Now that I know it runs great, I need to get this fixed and am anxious about getting it on the water. Any help is greatly appreciated.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 1970 Mercury 800: Will start, but shuts off when key is released.

Distributor motor?

Get the free Ignition Troubleshooting Guide from the Support pages of CDIElectonics.com

Follow the detailed instructions on how to test the distributor trigger, this is classic symptom of a failing trigger.

CDI makes a replacement distributor body with the new trigger installed.
 
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