78 merc. 90HP no spark

[fishingdude81521]

hi I have been reading on several forms about the no spark on the 78 merc. 900 90HP inline 6. I found several forms talking about removing the 3 wires from the switch box and jumping the white and brown wire then removing the coil wire to ground it to test the trigger. the all say what it is if it sparks.. but what if it don't? I filed off some paint on a bolt to make sure I was getting good ground I tested it with a light to make sure and it was. when I hold it near the clean spot and ground the black wire. ( top post) there is no spark. is there a way to test the switch box? or coil?

​Thanks

 

[Chris1956]

That test procedure is detailed on the CDI Electronics web site. I suggest you follow it exactly. It will test the switchbox, coil and wiring to assure they are good.

By elimination, it tests the trigger. That is, if the test shows you have spark when bypassing the trigger, and no spark when using the trigger, the trigger is likely bad.

 

[fishingdude81521]

I have no spark when I bypass the trigger but I have been unable to find any instruction on checking the switchbox. I found some for the trigger. and the stater. (SP) but none on the switch box.... ill look again thanks

 

[merc850]

If the sparks don't happen when you do the trigger test it means the switchbox and/or coil are defective or no voltage (+12) on the red and white wires.

 

[fishingdude81521]

yes no spark when bypassed. and I do have 12 V on red and 12 V on white with key on... I ordered a switchbox... thanks for the help