1980's 18hp briggs wont stay running

[metz12]

So I was getting my 91 year old grandfathers trusty ole craftsman ready for the mowing season. After I finished I decided to take it for a spin and it drove like normal for about 5 minutes then shut right down. The model number is 917.253740 and its a 18hp briggs and the mowers year is somewhere around the 1980's. I don't know if it could be a coil? Or could it be something else? If it was the coil how would I test it? Thank you in advance.

 

[ILENGINE]

The easier way is to remove the plug, reconnect the wire and ground them to the block, and crank the engine to see if you have fire.

You didn't mention if this is a single or twin cylinder. if twin, ground both plugs at same time and see if spark continues. Had one a few years ago that would fire if one plug was grounded, but not both. Report back your findings, and somebody will give further advice. Like how to check the key switch to make sure that it isn't shorting 12v to the module, causing immediate failure.