Re: Help please merc 150 no spark one cyl.
Here is the ADI Troubleshooting procedure..
Inline 6 and V6 Engines Using Dual Switch Boxes and Six Ignition Coils
No Fire At All:
Disconnect the black/yellow kill wires AT THE PACK and retest. If the engine?s ignition fires now, 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 cranking RPM. A cranking speed less than 250-RPM will not allow the system to fire properly.
No fire or Intermittent on One Bank (Odd or Even Cylinders ? L-6):
Check the stator resistance and DVA output as given below:
9 to 16 Amp Battery Charging Capacity
Wire Read To Resistance DVA
Blue
Blue/White
Red
Red/White Engine GND
Engine GND
Engine GND
Engine GND 5000-7000
5000-7000
90-200
90-200 180V or more
150V or more
25V or more
25V or more
40 Amp Battery Charging Capacity
Wire Read To Resistance DVA
Blue
Blue/White
Red
Red/White Engine GND
Engine GND
Engine GND
Engine GND 1000-1600
1000-1600
75-90
75-90 150V or more
150V or more
20V or more
20V or more
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 on all cylinders. If the reading is low on one bank and the stator voltage is good, the switch box is likely bad. (Note: A final test to verify which component is bad is to swap the stator leads from one switch box to the other. If the problem moves, the stator is bad. If the same bank stays down, the switch box is bad.)
Check the cranking RPM. A cranking speed less than 250-RPM will not allow the system to fire properly.
No fire or Intermittent on One or More Cylinders:
Note: If two cylinders on separate packs are not firing, check the trigger as described in # 1 below. The trigger has three coils firing six cylinders. #1 and 2 share a trigger coil, 3 and 4 share a trigger coil and 5 and 6 share a trigger coil.
Connect a spark gap tester and verify which cylinders are acting up. If the cylinders are only acting up above an idle, connect an inductive RPM meter to all cylinders and try to isolate the problem cylinders.
Check the trigger resistance and DVA output as given below:
Wire (yellow sleeve) Read To (black sleeve) Resistance DVA (connected)
Brown wire(#2)
Purple wire(#4)
White wire(#6) Purple wire(#1)
White wire(#3)
Brown wire(#5) 800-1400
800-1400
800-1400 4V or more
4V or more
4V or more
Note: You should get a high or open resistance reading to engine ground from each wire, but you will get a DVA reading of approximately 1-2 Volts. 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 out put 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.
