Last summer I put an LS1/T56 into a Miata. It has now developed a problem where it sometimes won't crank the starter or fuel pump when the key is turned. If I leave the key on, leave the car in gear, and rock the car back and forth, the fuel pump winds up and turning the key will now start the car.

What would cause this? I know there is a clutch switch, but I do not have the clutch disengaged when rocking the car. I can't think of any ignition or fuel cutout that is tied to the transmission or crank position. ideas?

 

almost sounds like a grounding issue somewhere.