Yamaha - Gear Pump Assembly Hydraulic Trim & Tilt System 6EK-43830-00-00. Overview. When trim and tilt starts getting slow or inconsistent, the gear pump is usually where I start looking. It's what keeps hydraulic fluid moving under pressure, so when it's worn out, you feel it every time you try to adjust the motor. I've replaced a few of these on older setups, and the difference is immediate-smooth, responsive movement again. It's one of those parts that brings the whole system back to life whe