Re: 85hp merc no spark
P-B, I would check the coil for continuity and no shorts, on the primary and secondary windings. I would check the coil to distributor wire for continuity(resistance should be zero), and well as the insulation and continuity (again should be zero resistance) on the spark plug wires. The coil to dist. and the spark plug wires are stranded stainless steel. However, the rubber covering gets cracks and allows the spark to short to the block. <br />If you need to replace the wires, look around the various intenet parts sites to get the best price. They range from $5 ea to $15 ea.<br /><br />If all this stuff is good, it is possible your switchbox or trigger is bad. here is Clams Canino's switchbox test procedure. (thanks Clams)<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
