This is a continuation of a previous thread but since two of the three issues mentioned in its subject line were resolved (P0171 and high LTFT) with a PCV diaphragm replacement I thought I'd post a new thread specific to the fuel pressure issue I'm facing.
I'm getting a P0088 code (fuel pressure too high) in my 2010 XC70 T6. When I look at other diagnostics the fuel pressure is in the 650 kPa range and the fuel pump duty cycle is constant at 80%. I installed a new spare FPS but no change in the P0088 code or measured fuel pressure. I hooked up DICE/VIDA to read the fuel pump duty cycle from start and it jumps immediately to 80% and stays there no matter what the driving condition or fuel pressure. So, what determines the fuel pump duty cycle? From my understanding the ECM tells the PEM what it should be based on measured fuel pressure and perhaps driving situation. Why would mine be stuck at 80% when the pressure is obviously too high already? Is the duty cycle read by VIDA the commanded or actual duty cycle? I've read the PEM controls the pump duty cycle by controlling the ground for the pump while supplying a constant 12v power. Could the ground be shorting so the pump is on too much? Or could 80% be a default when some other control signal is missing?
I'm getting a P0088 code (fuel pressure too high) in my 2010 XC70 T6. When I look at other diagnostics the fuel pressure is in the 650 kPa range and the fuel pump duty cycle is constant at 80%. I installed a new spare FPS but no change in the P0088 code or measured fuel pressure. I hooked up DICE/VIDA to read the fuel pump duty cycle from start and it jumps immediately to 80% and stays there no matter what the driving condition or fuel pressure. So, what determines the fuel pump duty cycle? From my understanding the ECM tells the PEM what it should be based on measured fuel pressure and perhaps driving situation. Why would mine be stuck at 80% when the pressure is obviously too high already? Is the duty cycle read by VIDA the commanded or actual duty cycle? I've read the PEM controls the pump duty cycle by controlling the ground for the pump while supplying a constant 12v power. Could the ground be shorting so the pump is on too much? Or could 80% be a default when some other control signal is missing?
