The problem is that the solenoid is very sensitve to less a voltage threshold to engage. What we did is put a simple relay that engages (it will actuate at 11 volts, or so).

Then you have that power the solenoid directly from the battery switch which works without a glich. You don't have any voltage loss in the connections back through the key switch assembly.

It is depressing to be at an anchorage with your batteries showing 12 volts and find-out that you're getting no action from the engine starter. (Of course, you cant go "jump" the solenoid with a screwdriver and some "googles" ;^) )