Mercury Thunderbolt 850

[trihull59]

Just bought a old merc motor serial number 3497531
not positivie on the year, but I bought it knowing it has no spark i was wondering what this could be and how i would go about testing to see what is going on i am clueless
i have heard it might be the switch box or coil?

 

[SeaKaye12]

Re: Mercury Thunderbolt 850

Hi,

Well; from your serial number you have one of the older style distributor type ignition systems. Probably a 1973. The parts diagrams and numbers can be found here:

http://www.dougrussell.com/partscat...tcomp&colid=01&coldesc=850 (4 CYL.)&index=461

There are a ton of posts on here explaining the ignition testing on your engine. I imagine one of the pros on here will walk you through it if you ask.

First off; I would check all your wiring. Those old Mercs are notorious for having a bad wiring harness.

Good luck, Chuck