I'm getting shocked

[doehunter]

I recently installed a '94 Yamaha C40PLRS on my aluminum jon boat.
It has the Yamaha 703 control with tilt switch in the handle.
When the motor is running, and I touch the neutral throttle lever and the steering wheel at the same time, I get shocked.
Nothing happens if I just operate the main throttle/shift lever.

Is there a ground wire or something I might have missed?
Maybe an insulation problem?
Is this common?

[boats.net]

Check all grounds on engine, make sure ground straps between transom bracket and motor mounts. look for shorted wires.