'87 Merc 150 VR4

joey nathan

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
185
Trying to get a possible V-6 purchase to go. Has fresh fuel, will not start. When I crank the starter with a (brand new) spark plug laying out on the block, no arc.

No 12V at the small wires on the coils, or the junction blocks/modules that are the source of the wires to the coils, either. Battery is brand new and 12V at start solenoid.

Is this lack of 12V problem caused by the module located under the flywheel?

I think I need a wiring diagram/service manual also. Any/all suggestions welcome...

Thanks...
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: '87 Merc 150 VR4

The ignition on that motor doesn't work like you are thinking. As the motor cranks, magnets under the flywheel cause a voltage in the stator. This voltage is sent to the two switchboxes where it is stepped up, rectified and stored. As the magnets pass the trigger coils, a signal is sent to the switchboxes to "dump" the voltage into the proper coil, causing a spark.

Get on the CDIElectronics.com website and download the troubleshooting procedure for your motor. Look for ADI ignition, 6 cylinders, two switchboxes.
 
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