no spark

[olsoncsb]

I have a 115 hp mercury with the thunderbolt ignition system. I think it was made in 1975 but I'm not for sure. Where can I find my serial number at? I also have a problem. My father game me his boat. When I got it I used jumper cables off my truck to start it. I think I might have burned up my switch box because I have no voltage going to my ignition coil. I also had my truck running when I jumped started my boat and did not have a battery connected to my boat motor. I didn't know any better. I think because I had to charging system running at the same time that this is what cause me to burn up my switchbox? I want to get parts to fix it but I don't know how check to see what parts are good or bad? How do I check these parts rectifier,switch box,trigger aka distributer housing? also would two charging system running at the same time burn up my coils for the trigger that is built into the distributer housing? Where can I buy parts that are hard to find at a reasonable price? thanks for any replies

 

[Merc805]

Re: no spark

Do you have a photo? We can tell the year from that. Or look on the transom bracket for the 7 digit serial no.

 

[Chris1956]

Re: no spark

Olson, It is hard to tell what is wrong from your description. It could be any/all of the ignition components. The coil may be checked for continuity on the primary and secondary side. I will add Mr. Clams Canino trigger test procedure to this post. The ignition parts for that motor are available, but they are expensive (at least I think so). I would track down some used parts at a junkyard ot on Ebay. Good luck. Also check the distributor cap, rotor and wires for cracks, carbon tracking and dirt.<br /><br />I think this is what you need, pretty sure Clams has posted this here before so I wanted to give him his due credit;<br /><br />MERCURY BATTERY-POWERED CDI TEST <br />FOR DISTRIBUTOR MODELS<br /><br />This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.<br /><br />This test assumes your coil is good (most all are).<br /><br />DISCONNCT BATTERY <br /><br />1. Turn off ignion<br />2. Disconnect all 3 wires on the distributor side of the switchbox.<br />3. Remove the HV lead from the coil to the center cap (remember it unscrews<br />from cap)<br />4. Reconnect that HV center lead to the COIL side only.<br />5. Position that HV lead about about 3/8" from ground (block, shrouds etc)<br />and find a way to hold it there.<br />6. Jumber the brown and white terminals on the dist. side of the switchbox<br />together.<br /><br />RECONNECT BATTERRY<br /><br />7. Check that you have +12 V at red terminal.<br />8. Turn on ignition and verify +12V at white terminal (on red terminal side)<br />9. Touch the black terminal to ground - unit should cause spark each time<br />you touch ground.<br /><br />If that passes and it won't fire at all, suspect the trigger

 

[randycc58]

Re: no spark

some mercs have the modle number on the freeze plugs on the head