Re: Johnson 1977 70Hp
I assume you mean no spark to all cylinders?? If the ignition only sparks with the spark plugs out, the timer base is likely weak or the engine is not spinning fast enough. See # 6 and #8.
1. Disconnect the black yellow stop wire and retest. If the engine's ignition has spark, the stop circuit has a fault-check the key switch, harness and shift switch.
2. Disconnect the yellow wires from the rectifier and retest. If the engine now sparks, replace the rectifier.
3. Check the stator resistance. Reading should be about 500 ohms from the brown wire to brown/yellow wire.
4. 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).
5. Check the timer base?s resistance from the black/white wire to the white/black wires. Reading should be 10-20 ohms (or 30-40 ohms for CDI Electronics Blue Timer Bases).
6. Check the DVA output from the timer base. A reading of at least 0.5V or more is needed from the black/white wire to the white/black wires (while connected to the pack) 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 using a Sensor Gap Gauge (553-9702) or use the following procedure outlined below.
a) Loosen the two mounting screws on the sensors and the nuts located in the epoxy on the outside of the heat shield of the timer base and slide the sensors in toward the crankshaft until the sensor touches the stop boss located at the base of the sensor mounting area. Tighten the mounting screws.
b) Coat the face of the sensor with machinists bluing or equivalent and install the flywheel without the key and rotate the flywheel at least one full turn. Remove the flywheel and check to see if the trigging magnet struck the sensor face. If it did, back the sensor out approximately 0.005? and repeat steps C, D and E.
c) If the ignition has spark, finger tight the nut on the outside of the heat shield and coat it with RTV.
d) If still no spark, replace the sensor.
7. Check the DVA voltage on the black/white wire to engine ground. You should have a reading of at least 150V or more (while connected to the pack). If the reading is low, disconnect the trigger wires from the pack and recheck the black/white terminal 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).
8. Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to fire properly.
