Dear Technical Representatives:<br /><br />The purpose of this letter is to alert Yamaha Motor Corporation to an operational condition on 2-Cycle Oil-Injection models that requires a technical review. Analysis below is based on the Owner's Manual and Technical Manual descriptions for Model 150TXRB 2-Cycle Oil-Injection system.<br /><br />My Model 150TXRB 2-Cycle Oil-Injection outboard is currently equipped with the standard tachometer and audible low-level oil alarm. An optional Yamaha Digital Tachometer is available and includes: Tachometer, Trim meter, Hour meter, Oil level indicator, Overheat warning indicator, Set button, and Mode button.<br /><br />The Digital Tachometer, compared to the standard tachometer and audible alarm, affords additional visual warnings for low oil-injector levels and water jacket temperatures, but both installations are deficient for Yamaha outboards:<br /><br /> There is no pre-check device or operational procedure described to test proper functioning of the low-level audible alarm switch set point. A switch failure preempts engine oil-injector reservoir level indicators.<br /><br /> In event of lube oil pump failures, there is no alarm system for low pump discharge to the intake manifold vapor separators. The oil level in the outboard oil reservoir will be high or normal but the engine is oil-starved without a visual and or audible alarm.<br /><br /> An optional Yamaha Digital Tachometer includes an Overheat Warning Indicator which would sound at the preset set point for jacket temperature in the event of a loss of oil-injection. This visual alarm, under full load conditions, would probably not allow lead time to prevent further damage to the outboard internals caused by injector-oil starvation.<br /><br />I recommend Yamaha investigate possible solutions to the issues above in order to make the 2-cycle outboard a more reliable product. I further propose that a dealer alert bulletin be issued that advises dealers and customers of these potential problems.<br /><br />Very truly yours,<br /><br />Terry D. Payne<br />Charleston SC<br />843-766-4437<br /><br />Copy to: Seels Outboard, Charleston, SC<br />Kerry Schroeder, Yamaha Regional Service Representative