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Johnson/Evirude Alternator Driven CD Ignitions
1972-1978 Engines
(With screw terminal type power packs)
Two Cylinder Engines
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No fire at all:
- Disconnect the black yellow kill wire and retest. If the engines now has fire, the kill circuit has a fault-possibly the keyswitch, harness or shift switch.
- Check the stator resistance. You should read approximately 500 ohms from the brown wire to engine ground.
- Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to engine ground (while connected to the pack).
- Check the timer bases resistance from the black/white wire to the white/black wire. Reading should be 10-20 ohms.
- Check the DVA output from the timer base. A reading of at least 0.5V or more from the black/white wire to the white/black (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet.
- Loosen the two mounting screws on the sensor and the nut located in the epoxy on the outside of the heat shield of the timer base.
- Slide the sensor in toward the crankshaft approximately 0.005” at a time.
- Coat the face of the sensor with machinists bluing or equivalent.
- Install the flywheel according to the service manual and crank the engine over.
- Remove the flywheel and check to see if the trigging magnet struck the sensor face.
- If the ignition fired, finger tight the nut on the outside of the heat shield and coat it with RTV.
- If still no fire, slide the sensor in another 0.005” and repeat steps C through F.
- Check the DVA voltage on each trigger wire to engine ground. You should have a reading of at least 150V or more from the black/white wire and the white/black wire to engine ground (while connected to the pack). If the reading is low, disconnect the trigger wires from the pack and recheck the terminals on the pack. If the voltage jumps up to an acceptable reading, the timer base may have a problem in the internal wiring (A thin spot in the insulation on one wire).
- Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to fire properly.
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No fire on one cylinder:
- Either a faulty power pack or ignition coil normally causes this. Extremely rare causes include a weak trigger magnet in the flywheel or a timer base.
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Three Cylinder Engines |
No fire at all:
- Note: If the ignition only fires with the spark plugs out, the timer base is likely weak or the engine is not spinning fast enough. See # 6 and #8.
- Disconnect the black yellow kill wire and retest. If the engines now has fire, the kill circuit has a fault-possibly the keyswitch, harness or shift switch.
- Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier.
- Check the stator resistance. You should read approximately 500 ohms from the brown wire to the brown/yellow wire.
- Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to the brown/yellow wire (while connected to the pack).
- Check the timer bases resistance from the black/white wire to the white/black wires. Reading should be 10-20 ohms.
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continued next page....
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Page 28 - Index - Page 30 |