1969 Mercury 350 weak voltage to spark plug

[lifeandliberty]

Well I think I've tried everything just not willing to give up. Catch you up to speed. Replaced every component in my magneto ignition system. Set new points @ .018, new condensers manufactured in 2002, New new magneto coils, new spark plug wires and plugs. I've cleaned the stator assembly ensuring no grease or dirt is present. ran some emery cloth across the points. set max spark at .300btdc. magnet on flywheel holds a 7/8" socket on tightly when trying to shake it off. someone told me the flywheel could have been reindexed. not sure what this means. moved flywheel in every configuration possible with no luck. could my stator be bad? how do i check it? any suggestions?

 

[skeets]

Re: 1969 Mercury 350 weak voltage to spark plug

Hello life&<br />Check this web site<br />Marine Techinal and Trouble shooting.<br />Good luck

 

[Chinewalker]

Re: 1969 Mercury 350 weak voltage to spark plug

One item at a time, try swapping coils, points, condensers from one side to the other and see if the problem follows any one of them. It's possible you bought a dud condenser or coil.<br /><br />Does your motor have a kill button or key switch? There should be a terminal block on the motor where the wires from the magneto go to join up with the ones from the kill/key. Make sure the screws that hold the wires to the terminal block aren't too long - had one that drove me nuts for a while trying to figure out why it lost spark after I assembled the motor. One of the screws was long enough to ground on the motor block and kill that cylinder...<br />- Scott

 

[lifeandliberty]

Re: 1969 Mercury 350 weak voltage to spark plug

chinewalker, thanks for the info. I completly removed the wiring harness & plan on using pull start only & will install kill switch once i solve the spark issue. does the flywheel on this year have one or two magnets on it. i have a magnet that bolts on. it is really strong however there is what looks like a counter weight on the other side. is this suppose to be a magnet too.

 

[Chinewalker]

Re: 1969 Mercury 350 weak voltage to spark plug

Hi L&L,<br /> Yes, there is only supposed to be one set of magnets, and there will be a counterweight (not magnetized) on the other side.<br /> One other thing you may wish to try - run a wire from one of the screws on the front of the armature, where the linkage bolts on (round head, slotted screws), down to the motor block somewhere to give a positive ground to the motor block. The armature to hub connection should have a film of oil/grease to allow easier timing advancement and prevent wear to those surfaces. Grease isn't a great conductor and sometimes a seperate ground wire from the armature to the block is needed.<br /> Keep plugging away - you'll get it. The magneto on those motors is too simple a system to let it get the best of you. I completely overhauled my '69 350 last winter and have been running it a lot this season. 35 horses on a 14-foot tin can, using a tiller - it's quite a ride!<br />- Scott