M750 only spark on 1

[fstdy]

I have a 2001 M750 thats only firing one plug. I tried swapping the two coild. Not the coil. Switch the wires going to the coils and it follows the wires. Checked connections etc. No broken wires. Anyone have ideas what this could be or what I can check to diagnose it?

Thanks

[64duc]

 Pull the sparkplugs and and read them first. White is lean, gray or brown is proper, and black is rich. I'm betting on rich.

[myssrhl]

lets first verify whether or not you have spark..... pull the plugs and check for spark while spinning the motor over....

[fstdy]

Sorry what I should have said was only spark one one side. swapped plugs, coils black boxes.

The CDI black boxes.. are they the two boxes located right beside the coils with a two wire and a three wire connector on them? If so I tried swapping them too. Problem didnt follow the black box.

I notice both coils have two posts. one post has two red wires attached and the other post has a grey wire on one coil and a black/red wire on the other coil. the problem seems to follow the grey wire.

[Howie]

I suspect you have  bad ignition pick up.  If you look at your ignition modules (CDI black boxes), the connectors with two wires are from the pick ups.  Each pick up should read 90 - 100 ohms.

[fstdy]

OK I have not measured the ohm yet however I did try swapping the two 2 wire connectors coming from the pickups going to the CDI black boxes. The problem did not follow one of the pickup wires.