My tach, oil temp, and oil pres needles are jumping around in unison. Have checked the grounds and they show fine but this is what I'm guessing it is related to. The alarm is not going off even when the oil pres needle drops to zero and boat is running fine. I hoping someone can point me toward the problem. Just purchased the boat.
Thanks.

Today I see a Mercury Smartcraft Analog Gauge Interface (AGI) box up under the helm. The gauge outputs it lists are all guages that are/have acted erratically. Has anyone had one of these go bad? I'm leaning toward it being a black box/computer related issue because the needles are jumping on a exact schedule (~ every two seconds).

If you have a Smart Craft analog converter, turn key to on, wait 5-10 seconds before starting. See if that doesnt cure your problem.

my jump too, but boat is older. I dont get it

Mine do the same thing if I turn key and start immediately, was told to wait a couple of seconds and it seems to eliminate that problem on my boat with Smart Craft. If I get distracted or forget to wait mine will jump also.

Thanks all for the input. I tried waiting 10 seconds and then starting. No luck, still jumping. Have a new AGI on the way...

New AGI box cured the hiccups. Thanks, KN