Mercury Thunderbolt 500 wont shut off?

[TitanTea]

It is a mid 70s motor with a MerControl. I can fire it up and then turn it off immediately with the key most of the time. If I run the engine for a minute or longer the key will not turn the motor off? I have to choke the carbs to kill the engine. Anyone have any idea what the problem could be?

 

[mike1245]

Re: Mercury Thunderbolt 500 wont shut off?

thiers a ground wire that goes from the switch box to the switch and a ground wire from bat to switch when u turn off key it connects those wires goto maxrules.com and get a schematic could be switch or could be wires

 

[TitanTea]

Re: Mercury Thunderbolt 500 wont shut off?

Thanks for the info!