1968 Merc 100hp

[Loren]

I recently accuired this 1968 100hp Mercury and it wouldn't start. I found no spark at the spark plugs so I replaced the distributor cap which was pretty worn. Still no spark, so I checked the coil and there is no voltage going to the coil. There are two wires going to the coil from a square box,(what I would guess is some kind of brain). There is 12 volts going to the box on another connection but nothing going to the coil. I'm not sure if this component is bad or if there is another reason the voltage would not go on to the coil? Any help would be greatly appreciated.

 

[Fitch]

Re: 1968 Merc 100hp

The coil will only get voltage when it is to be fired. Most common problem on these older motors was the trigger coil in the distributor. They aren't the easiest to work on so if you bring it to a shop get an estimate before they fix it.

 

[Loren]

Re: 1968 Merc 100hp

Thanks ! I had pretty much eliminated it down to the distributor but I was told that they were kind of tricky to take apart if you didn't know what you were doing. So I've been looking for somebody that would work on it but so far everyone I've talked to has said if it's over twenty years old that they don't work on it.

 

[Lou]

Re: 1968 Merc 100hp

the distributers on those moters are the magneto type. there should be absolutly no voltage any where on it except when it "clicks" over, and then there will be a LOT more than 12 volts. If you have ever been shocked by a spark plug, well....thats how much voltage there will be. if you do have voltage there at rest, it is wired wrong. that motor with the "mag", should run by default (no power added except a pull on rope or crank on the starter) if you want it to stop after you get it running you dont "shut the switch off", you actually ground the system out, killing the self produced spark from the "mag" to the spark plugs. and the ground wire should be the only small one on the "distributer cap". if you have hooked it up like an automotive ignition with battery voltage you have fried the points for sure. ($35-40°°) and possibly injured the coil and condenser as well, but not necessarily. remove it from the engine and open it up and you will see what you need from the parts house. good luck...Lou

 

[ODDD1]

Re: 1968 Merc 100hp

bullcrap is a mag...is battery cd system...if you got power to the box an no spark ...99%of time trigger in distributer base is failed ..good luck finding one ...early ones were special....