Brief Description: Fuel Pump Troubleshooting and Gauge Calibration
Plans: 1. Troubleshoot fuel pump activation. Status: Complete. I found that one of the two pumps was magically working today. The other was still in-op. I disconnected the troubled pump from the bracket such that I could try different orientations. Nothing worked. I verified that fuel was indeed available at the inlet. Still nothing. I read that there was a shut-off valve internal to the pump and wondered if that was somehow the problem. I shook the pump back and forth like a can of spray paint. It rattled a bit and began to work. So the internal valve is the issue. I reassembled the system and it has worked fine ever since. 2. Calibrate fuel gauge. Status: Complete. The fuel sender has potentiometers to calibrate empty and full levels. I set the gauge to read empty with three gallons during level flight. It reads full with ten gallons in level flight. The tank should hold more than ten gallons based on the ad-hoc sight gauge. I heard that 13 gallons is possible when filled to the brim. I chose three gallons for empty because I predict two gallons is not useable. A reading of empty could easily result in the engine stopping depending on the AOA. Full at 10 gallons is easy to remember and do in-flight fuel estimates. 3. Test fuel flow. Status: Complete. Both pumps were used to empty the tank. The flow appeared adequate. The pumps ran cool and consumed 3 amps each while on. A stalled pump used 15 Amps. 4. Continue avionics hook-ups. Status: 90% complete. I added wiring for the alternator field circuit and coolant temperature sensor. I have decided to directly connect the field line to the battery using a dedicated wire. This will result in the necessity to turn the ALT switch off after every flight. The battery would drain otherwise. On the positive side, alternator charging will not be influenced by voltage drops from fuel pump operation.