Universal M50 tach problem

[Scott Fuller]

New boat for us, replaced the engine instruments and redid the entire engine wiring harness eliminating trailer connectors. The new Faria tach is very erratic on the two occasions I have run the engine, reads zero until the engine is revved, then returns to zero when engine is idled. After searching the forum I found a thread discussing that if there is no charge current, the tach won't operate. I have a Balmar alternator with an older Balmar BRSII regulator and I suspect this is the issue as the boat has been sitting on shore power with no load on the batteries. I am wondering if anyone knows if the Universal M50 has a port for a proximity sensor?

[donradcliffe]

Turn a bunch of DC load on and see if the problem goes away.

[sailah]

Where the blue and white wire go into back of Balmar alternator there is a plug. On my westerbeke this plug sometimes doesn't make good contact unless i wiggle it. I need to bend the contacts out one of these days but it's been fine for months now.

Same issue tach would jump around esp at low revs or startup.

[tkeithlu]

Damn! I wondered why my electric tach (to Balmar alt) jumped around while my magnetic probe tach was right on, just after starting. Thanks a bunch!