Re: 76 merc 115 outboard no spark at all
The test you need is the switchbox test. It does not go in to detail here. But it is in the wiring diagram. You disconnect the trigger wires and then you put a jumper wire from the Brown to the white terminal on the box. Then you arc the black wire to ground it should spark every time. If the switchbox is good. That will mean the trigger is bad. You need to double check and make sure what wires to jump per to your switchbox #. I cant hardly read it on my monitor. It is blurry.
Go here and see if you can see what wires to jump. I think you have 332-2986 Fig B.
http://www.outboardparts.com/mercury/troubleshooting/printguide.htm
do you have 12V to the red terminal on the switch box?
do you have 12v at the white terminal when the key is turned on?
MERCURY BATTERY-POWERED CDI SWITCHBOX TEST
FOR DISTRIBUTOR MODELS
This test is for the 332-2986 switchbox used from 1967-1978 on all the
inlines.
This test assumes your coil is good (most all are).
Disconnect the mercury switch (kill switch)
DISCONNECT BATTERY
1. Turn off ignion
2. Disconnect all 3 wires on the distributor side of the switchbox.
3. Remove the HV lead from the coil to the center cap (remember it unscrews
from cap)
4. Reconnect that HV center lead to the COIL side only.
5. Position that HV lead about about 3/8" from ground (block, shrouds etc)
and find a way to hold it there.
6. Jumper the brown and white terminals on the dist. side of the switchbox
together.
RECONNECT BATTERRY
7. Check that you have +12 V at red terminal.
8. Turn on ignition and verify +12V at white terminal (on red terminal side)
9. Touch the black terminal to ground - unit should cause spark each time
you touch ground.
If that passes and it won't fire at all, suspect the trigger.
