Review on Yamaha Deluxe Engine Meter Hour/Tach ENG-METER-4C-01 by Marley Woods

Installed according to the instructions on a brand new Yamaha outboard motor. Used to control hours and revolutions for break-in. After hitting the recommended hours, I ran the engine at full power to check the maximum RPM. Readings were stable up to about 4500, then started to jump to varying readings from 4500 to 6000. I've tried reinstalling with extra turns around the connector wire, the reaction is the same. I paid extra for this device because of the big brand name which was very disappointing. Dismantled and returned for a refund.