Zero Spark

[myelo]

I have a '72 Merc 650. After the winter, it started briefly, then wouldn't start again. I changed plugs and rebuilt carbs, changed gas, cleaned lines, checked fuel pump. Tried again....started twice, but wouldn't keep running. Now won't start. I checked plugs and there is NO SPARK from any of them. Compression 110 on all 3 cylinders. I haven't a clue what to do now. Suggestions??? (simple ones I hope!)

 

[Laddies]

Re: Zero Spark

Start by cking to see if your timing is broken, then disconnect the mercury switch from the switch box, the next step is to ck the switch box let us know if you still have no spark and we can talk you through the test, it's really quite simple--Bob

 

[timmathis]

Re: Zero Spark

Just listen and they will get you going!

 

[myelo]

Re: Zero Spark

Thanks so much everyone! I finally get it started again, but now I have new problem (actually 2 new ones!) ugh!!. I will post seperately. Thanks again!

 

[digger6106]

Re: Zero Spark

rear admiral.

i have a 74 115 merc. how can i test the switch box and dist. without taking them to a merc dealer. i lost all spark, coil test is ok, my manual says take others to dealer to test. thanks

 

[Plainsman]

Re: Zero Spark

Digger...you may want to start your own post of this problem....
The credit for this goes to clams who helped me:

HOLD ON... try this test....

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 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.

 

[digger6106]

Re: Zero Spark

i appologize for jumping in but i tried my own thread and it would not let me post it. my appologies

 

[digger6106]

Re: Zero Spark

thanks for the test. i will try it tomorrow.