Problem with Autometer boost gauge install

I installed a new Autometer vac/boost gauge in my old Omni GLH Turbo today. I replaced the broken mechanical Autometer Phantom gauge with an electric 3-bar MAP sensor driven Phantom gauge.

I seem to have a problem with the 12v positive wire that powers the gauge though. I hooked it up to the same switched power source as the stereo, and while cranking the car the ignition switch cuts power to this circuit. This causes the gauge to auto calibrate a 2nd time when the switched power comes back after returning the key to the 'run' position from the 'start' position. Since the engine is running (and pulling vacuum) at this point, the gauge is reading way off.

Is there a switched power source that I can hook this gauge up to that doesn't lose power while cranking, but shuts off with the key in the 'off' position?

So far the only way I've gotten the gauge to read accurately is by shutting the engine off while driving, then turning the key back to 'run' position and letting the clutch out in gear to start the engine. This way the gauge doesn't lose power and screw up the auto calibration while cranking.

Would the Z1 feed from the ASD circuit work for this?

The power going to the LM will supply power during cranking.

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Originally Posted by going4speed

The power going to the LM will supply power during cranking.

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Thanks. I'm going to give that a try tomorrow morning.

I rewired the boost gauge power wire to the LM switched power input at the red connector on the Omni today. Gauge works perfectly now. Thanks for the suggestion.