Volvo Penta 3.0 GL RPM gauge not reading correctly

[mckaras]

RPM gauge responds when throttle applied. However in idle it registers only 200-300 RPMs. It's a 2005 engine and the RPM gauge is linked to the ignition coil which is not OEM. I need help where to start chasing the problem down and how to test the diode that goes to those grey and purple wires that connect at the ignition coil. If it could not be the diode, please let me know where else to start chasing things down.

 

[Bondo]

RPM gauge responds when throttle applied. However in idle it registers only 200-300 RPMs. It's a 2005 engine and the RPM gauge is linked to the ignition coil which is not OEM. I need help where to start chasing the problem down and how to test the diode that goes to those grey and purple wires that connect at the ignition coil. If it could not be the diode, please let me know where else to start chasing things down.

Ayuh,..... On the back of the gauge, there's a switch, move it full scale a couple of times, set it back to match yer motor,.....
'n Try it,....

 

[Scott Danforth]

most likely crud on the multi-fit selector switch like Bondo mentioned. it may also be set to 8 cylinder vs 4 cylinders

 

[mckaras]

most likely crud on the multi-fit selector switch like Bondo mentioned. it may also be set to 8 cylinder vs 4 cylinders

Thank you I completely forgot! One of my employees must have not selected the correct setting when he installed the gauge!

 

[mckaras]

Ayuh,..... On the back of the gauge, there's a switch, move it full scale a couple of times, set it back to match yer motor,.....
'n Try it,....

Thank you!!!! I forgot about the switch, either there's crud or switched to the wrong position!

 

[mckaras]

most likely crud on the multi-fit selector switch like Bondo mentioned. it may also be set to 8 cylinder vs 4 cylinders

I have it set to 4 cylinders but will try and see if it will help changing it back and forth a few times!