92 Yamaha 70 - Water Pressure Gauge Issue

[whalergls15]

I have installed a brand new Yamaha water pressure gauge and the gauge always reads zero regardless of the rpm's. The engine performs well, does not overheat, and I have a steady stream from the tell tale. I have also have checked for blockages in the tubing but it seems to be okay. Any ideas ? Should a water pressure gauge work with this engine ?

[boats.net]

The 60 and 70HP engine have a low pressure high volume cooling system therefore you can use a water temp gauge but not a water pressure gauge.

[whalergls15]

Is this documented anywhere ? Yamaha shows the water pressure gauge as an available accessory in the gauge section for the 70. Thanks for the info in advance.