no spark at times

[hustler]

have a man.code F1692 that has no spark at times. 7 volts on neg side of coil when it has spark and 3 volts on neg side of coil with no spark, any ideas?

[gaminde]

Well on the neg side of the coil should be nothing. Any how do you have a rev limiter, bad cap, bad connection, bad coil, clean off coil connections. Bad points

[Michael Eddie]

7 volts on negative side? How is that? Something is up.

[Ralphsfarm1@yahoo.com]

7 volts on negative side? How is that? Something is up.

If the points are open (not making contact) there will be voltage there,
it should go to zero when the points or Igniter etc. makes. as the engine turns you should see the voltage go from 7 to zero as the engine turns.
If it doesn't bounce up and down as the motor is turned the points ( or equivelant component) aren't making and there will be no fire as the collapsing of the magnetic field when the circuit is broken generates the spark.
Hope this is helpful.
Ralph

[gaminde]

If the points are open (not making contact) there will be voltage there

This is correct! and it also is not the negative side it is the positive side at this point. It might be best if you found an old dwell meter at a garage sale.

it might be the negative side of the coil, but there was no talk of a coil, and if the circuit is open then there is no negative side ? its not a complete circuit.

Just semantics I guess I understand what your saying now.

so it could be a bad capacitor, points, coil, is there an electronic module running the ignition.

[Ralphsfarm1@yahoo.com]

I was speaking to an assumed negative ground system that had seperate points or equivilent, the negative connection of the coil is normally the switched side of the coil
( it reverses on positive ground I/e. my 1956 John Deere 420 tractor). I have found that
the capacitor (condenser) can cause the voltage to run low as mentioned or there can be a high resistance short thats keeping a current going through the coil so the coil doesn't fire a ( shorted semi conducter in an igniter could cause this ).
These all apply to the kettering ( battery) ignition, many Magneto Ignitions go to
ground through the points but are very difficult to read with a volt meter.
Some of the newer "Coils" on magneto ignitions have the whole ignition inside
so you have to replace the whole thing if there's no fire, I've seen no literature
on specifics (schematics etc.) on how they work, I assume they fire on the trailing edge of the induced voltage as the magnet passes the coil but I don't really know.
I think you're on the right track as Gaminde says , it could be condensor, points ,
module, or coil, in my experience the likely hood is in the order i listed.