1970 Mercury 115 no spark

[running2dogs]

Last fall I had trouble with spark one time I went out it had spark then the next it didnt. this spring same thing . I hasd the coil tested, it was good, then I replaced the wire harness the engine side. now I am thinking the CDI(Brain box) then mabey the triger. what do you think. Is there any way to test these parts to see if they are bad . Thank you

 

[JB]

Re: 1970 Mercury 115 no spark

Howdy, R2D.<br /><br />Sounds like you are in the right territory.<br /><br />It would be a really good investment to get a Service Manual which will guide you through troubleshooting the ignition system.<br /><br />Good luck.

 

[skeets]

Re: 1970 Mercury 115 no spark

Hello running<br />To test a coil connect a spark gap tester to the high-tension lead coming from the ignition coil and set it to app. 7/16".Crank the engine over,if it fires while the spark gap tester is connected and does not fire through the plug wires look for a problem in the distributor cap,rotor,plug wires.

 

[12Footer]

Re: 1970 Mercury 115 no spark

Skeets has the right steps to check,. and in that order.<br />These mercs have a nasty habit of stripping out at the rotor. Remove the cap, and see if you can rotate the rotor with one finger. If so, iot stripped-out at the cam, and you must replace the entire dist shaft/rotor assembly. I was tempted to try a spot of JB-WELD or MARINE TEX to tie it back down,because the shaft is rare and 'spensive.<br />But I have beenb lucky at finding them on ebay and local boatyards for under 50 buks...So far.

 

[running2dogs]

Re: 1970 Mercury 115 no spark

Thanks for the tips, Happy boating