EMU 912iS Fuel Pressure Indication Troubleshooting

Transcription

1 The correct fuel pressure reading of the depends on the following factors: Selection of the correct pressure sensor (Rotax P/N ) Correct fuel system installation and position of the fuel pressure sensor in the fuel line Correct wiring between the fuel pressure sensor and the Auxiliary connector The fuel pressure system is specified in the installation manual and should look as shown in Figure 1. Figure 1: Fuel Pressure System The Rotax pressure sensor connector pinout is shown in Figure 2. Figure 2: Pressure Sensor Connector Pinout Page 1 of

2 The connection between the fuel pressure sensor and the EMU, with the fuel pressure sensor connection framed in red, is shown in Figure 3. Figure 3: Connections The connector pinout of the EMU Auxiliary connector is shown in Figure 4. Pin 1 Figure 4: Auxiliary Connector Page 2 of

3 With the engine running, the fuel pressure as transmitted by the sensor will vary with power setting. This is the normal behavior and should be verified by analyzing the recorded engine data using EMDS (see Figure 5). OK Figure 5: Correct A steady fuel pressure as shown in Figure 6 (regardless of its value) is a clear sign of a installation error in the pressure sensor wiring, a defective or clogged pressure sensor, or a defective EMU input circuitry. Not OK Figure 6: Wrong Page 3 of

4 The Reduced Fuel Pressure which is displayed on the EMU main page is calculated from the pressure signal from the sensor, minus the manifold pressure of the engine. This is according to the fuel regulator specification. If the sensor pressure readings are not as shown in Figure 5, the wiring between the sensor and the EMU should be checked first. Make sure that the 5V excitation voltage can be measured between pins B and A of the fuel pressure sensor (refer to Figure 2). Then, make sure that the voltage between Pin C and A of the fuel pressure sensor varies when the fuel pumps are turned on and off. The sensor output voltage must always be in the range of 0.5 VDC to 4.5 VDC, as shown for the pressure sensor characteristics in Figure 7. Figure 7: Rotax Pressure Sensor Characteristics For the relevant fuel pressure range, the following values must be measured between pins C and A: 1 bar -> 0.5 VDC 2 bar -> 0.9 VDC 3 bar -> 1.3 VDC 4 bar -> 1.7 VDC 5 bar -> 2.1 VDC 6 bar -> 2.5 VDC The EMU allows for the correction of the displayed fuel pressure value to anticipate small differences of the fuel pressure caused by caveats of the installation. In order to verify if the real fuel pressure deviated from the measured fuel pressure due to the position of the sensor, or the size and length of fuel lines or other side effects, the pressure at the sensor should be checked using a fuel pressure test adapter as shown in Figure 8. Page 4 of

5 Figure 8: Fuel Pressure Test Adapter If an installation dependent small deviation of the fuel pressure (in the range of +/- 0.5 bar) is detected, this may be corrected using the CONF page of the EMU (see Figure 9). Figure 9: Fuel Pressure Correction Page Page 5 of