Rev Counter

[propwash]

Just bought a 2002 Wellcraft fitted with Faria gauges, the rev counter never reads right and has a mind of its own, possibly the fuel gauge isnt right either as it reads full and then I can put £80 of petrol in, as soon as I touch the trim button for the leg or move the trim tabs the needle goes to maximum, there is 12 volts going to the gauge when the button is pressed.
Anybody any suggestions.
Thanks

[scottyboy]

Sounds like an earth prob to me mate! Easiest way to check it is to run an earth straight from the batt to the gauges and see wot happens!

[propwash]

Thought it was going to be as well, didnt have a length of wire long enough at the time to try but wondering now if there is a bad earth then it wouldnt still be giving 12 volts to the gauges when the trim motors working? am I right or wrong?

[Burty]

might be getting its earth back through the trim motor