| Page 21 - Index - Page 23 |
Mercury
Alternator Driven Ignition Systems
Two Cylinder Engines (continued)
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No fire or Intermittent on One or More Cylinders:
- If the cylinders are only acting up above an idle, connect a inductive Tachometer to all cylinders and try to isolate the problem cylinders.
- Check the trigger resistance and DVA output as given below:
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| |
Wire |
Read To |
Resistance |
DVA |
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| |
Brown wire(#1)
White wire(#2)
Purple wire(#3)
Brown wire(#1)
White wire(#2)
Purple wire(#3) |
White/black
White/black
White/Black
Engine GND
Engine GND
Engine GND |
800-1400
800-1400
800-1400
Open
Open
Open |
4V or more connected
4V or more connected
4V or more connected
1V or more(a)
1V or more(a)
1V or more(a) |
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- (a) This reading can be used to determine if a pack has a problem in the triggering circuit. For instance, if you have
no fire on one cylinder and the DVA trigger reading for that cylinder is low – disconnect the trigger wire and
recheck the DVA output to ground from the trigger wire. If the reading stays low – the trigger is bad.
- Check the DVA output on the green wires from the switch box while connected to the ignition coils. Check the
reading on the switch box terminal AND on the ignition coil terminal. You should have a reading of at least
150V or more at both places. If the reading is low on one cylinder, disconnect the green wire from the ignition
coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is
likely bad. A continued low reading indicates a bad power pack.
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Engine will not rev beyond 3000-4000 RPM:
- Connect an inductive Tachometer to all cylinders and try to isolate the problem. A single cylinder dropping fire will likely be the switch box or ignition coil. All cylinders acting up usually indicate a bad stator.
- Connect a DVA meter to the stator’s Blue wire and do a running test. The DVA voltage should jump up to well over 200V and stabilize. A drop in voltage right before the problem occurs indicates a bad stator. (Blue to Engine GND if the engine has a Red stator kit installed).
- Connect a DVA meter to the Red wire. The DVA voltage should show a smooth climb in voltage and remain high through the RPM range. A reading lower than what is on the Blue wire indicates a bad stator.
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No Fire At All:
- Connect an inductive Tachometer to all cylinders and try to isolate the problem. A high variance in RPM on one cylinder indicates a problem usually in the switch box or ignition coil. Occasionally a trigger will cause this same problem. Check the trigger as described above under “No fire or Intermittent on One or More Cylinders”.
- Perform a high-speed shutdown and read the spark plugs. Check for water. A crack in the block can cause a high speed miss when the water pressure gets high, but a normal shutdown will mask the problem.
- Remove the flywheel and check the triggering and charge coil flywheel magnets for cracks or broken magnets.
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Three Cylinder Engines
1996-2000
Three Cylinder Engines Using a Combination Switch Box and Ignition Coil (CDM Modules) |
No fire at all:
- Disconnect the black/yellow kill wires from the harness and retest. If the engine’s ignition fires now, the kill circuit has a fault-possibly the keyswitch, harness or shift switch.
- Disconnect one CDM module at a time and see if the other modules start firing. If they do, the module you just unplugged is bad.
- Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier.
- Check the cranking RPM. A cranking speed less than 250-RPM will not allow the system to fire properly.
- Check the stator resistance and DVA output as given below:
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| |
Wire |
Read To |
Resistance |
DVA |
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| |
White/Green |
White/Green |
500-700
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180V or more |
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continued next page....
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| Page 21 - Index - Page 23 |
