Yam 115hp 4st new tachs not working :-(

[cereza]

Hi
I have read a few posts with similar problems but as yet have not seen anyone say they have found a fix.
Am hoping someone has! ;-)
I have recently bought a boat that has twin 115hp yam 4stroke 2003/04 models
When i bought the boat both tachs (faria combo's) were not working (factory fitted by boat builder)- i bought 2 new faria gauges and they are not working either.
They are wired to the green wire from ignition, when motors are turning over there is a signal coming thru (tach go up to around 750rpm) when the motor fires and idles the needle drops down to zero and just flickers slightly.
Unlikely that two faulty tach and two broken/faulty signal wires!! - but then i guess stranger things have happened.
I have installed two of trim and volt meter and one fuel gauge - all stem from the same power source (yellow wire from ignition) and all work fine -tachs are wired in with these gauges -have wired the tachs seperately and still no difference....

Any ideas welcome

many thanks
Bill

[boats.net]

Check that the tach settings are set for 12 pole alternator. If have an ac voltmeter then can check the signal voltage on green wires to tachs, voltage should increase as rpm's increase.

[cereza]

Hi thanks
forgot to mention -yes is set on 12 pole -
if the volts not increasing (form signal wire) does this mean a problem at the ECU?

[boats.net]

Yes or wiring problem.