It's hard to imagine only 2 PSI keeping a switch turned on. I'd suggest going to a switch with a higher pressure rating, or using a pedal-mounted mechanical switch. You can also power the hot side of the circuit with a wire from the ignition so it's powered off anytime the engine isn't running.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!