Checking electronic ignition on pre twin cam motors.
First check for adequate power to the coil should read battery voltage or close to it with the ignition and run switches on.
Next, disconnect the side of the coil that goes to the ignition module
(i.e. the wire that isn't 12v), and run a jumper wire
from that coil terminal to ground, with a point ignition condenser
attached.
I have a harness made up just for this test,
an alligator clip with two wires coming off, one to the condenser, and
the other is a bare end. Ground the condenser and the bare end, turn on the ignition, this powers up the coil and
charges the condenser. Now watch for spark at the plug when
you disconnect the bare end from the chassis ground, you should get a nice fat blue spark. If not, the coil is toast or the plug or plug wires are in question.
Restore the coil connections...
If you have good spark here, then you only have two main pieces left to check, the ignition module and sensor plate.
First go to the ignition module and test it for good power and ground,
fix it if not.
Next check is the sensor plate connector, a three-pin connector. First visually check the connector for anything obvious, like it's not plugged in all the way or a damaged terminal.
You'll see three wires colored red, green, and black.
On the ignition side of the connector, jump across the red and green
and you should see spark. If not, the module is
toast. If you do, then move on to the sensor plate, pop the nose
cover off and have a look, mark the plate's position
and then remove it, make sure the rotor cup is bolted to the cam
securely, and it rotates when you crank the engine.
Plug the sensor plate back in and watch for spark as you slide
something metallic through the slot. No spark?
Put in a new sensor plate.
First check for adequate power to the coil should read battery voltage or close to it with the ignition and run switches on.
Next, disconnect the side of the coil that goes to the ignition module
(i.e. the wire that isn't 12v), and run a jumper wire
from that coil terminal to ground, with a point ignition condenser
attached.
I have a harness made up just for this test,
an alligator clip with two wires coming off, one to the condenser, and
the other is a bare end. Ground the condenser and the bare end, turn on the ignition, this powers up the coil and
charges the condenser. Now watch for spark at the plug when
you disconnect the bare end from the chassis ground, you should get a nice fat blue spark. If not, the coil is toast or the plug or plug wires are in question.
Restore the coil connections...
If you have good spark here, then you only have two main pieces left to check, the ignition module and sensor plate.
First go to the ignition module and test it for good power and ground,
fix it if not.
Next check is the sensor plate connector, a three-pin connector. First visually check the connector for anything obvious, like it's not plugged in all the way or a damaged terminal.
You'll see three wires colored red, green, and black.
On the ignition side of the connector, jump across the red and green
and you should see spark. If not, the module is
toast. If you do, then move on to the sensor plate, pop the nose
cover off and have a look, mark the plate's position
and then remove it, make sure the rotor cup is bolted to the cam
securely, and it rotates when you crank the engine.
Plug the sensor plate back in and watch for spark as you slide
something metallic through the slot. No spark?
Put in a new sensor plate.