RPM indicator jumps to full RPM on startup-gctid828358

[Guest]

Hello,

Got following issue with my '89 Ciera 3.0 with basic style (not star wars style ) instrument panel indicators.

I started the engine (cold climate, was hard start and needed several attempts), RPM indicator jumps to full RPM and stays there. Engine runs about 800-1000rpm. Then i shut down the engine after warmed up and switch power off, still stays on full rpm. I tried technical knock to the rpm indicator, that does not help. When boat was a few hours battery unconnected, rpm needle is back on normal 0 rpm. Is there some voltage staying in gauge or what is caused this problem?

[Centerline2]

it sounds as if you have just experienced a catastrophic tach failure... if you shut the key off and the engine dies, that means the power to the tach dies too, as they run off the same circuit...... it could also mean that the tach wire has lost connection somewhere between it and the engine....

some tachs needles will stay where they were when their signal died... you should be able to check the circuit for a signal when the engine is running at the back of the tach with a test light or multimeter.... when the engine stops turning, the signal dies...