I have had a fuel delivery problem with my 2008 CS now for a few months. I have replaced the FPR, filter, and two fuel pumps...but am still having issues with a long crank time and pretty crappy running over 2K RPMs. Sometimes, usually when car is cold, the car will run perfectly, but once it heats up, it begins to act up.
I have a car scanner that can read some of the Porsche values so I decided to check on the high pressure at start up, and after running for awhile.

Ok...so after car warms up, the fuel pressure set point goes to 0.00...actual stays constant at around 5K mbar....at this point, you can give it gas and the actual value might go up to 6500 mb, but thats it....set point does not change.

I turned off the car and back on...I get a fuel set point of 40,000 mbar...actual around 32,000 mbar....car seems to run pretty good right after a restart...I gave it some gas, and the fuel set point went to 51000 mbar and the actual kept pace at 49800 mbar. BUT, after a few minutes the setpoint drops to 0.00 and stays there, and the actual again stays at 6500 despite giving it some gas. trying to bump it up.....

So what does all this mean? Seems like my HPFP is dying out after the car warms up...although even at start up it does seem to be running that well as it takes awhile for the car to start. Could it be a bad relay? Which relay is for the HPFP? Perhaps I can swap it out with another similar relay to test. Is there something else that would trigger the HPFP to turn off? Thanks in advance for any help.

 

Hi, was it your HPFP? Kind regards

 

Hi, do you know what the right values should be at idle? Because mine gives me a setpoint of 40000mbar but the actual value is around 5500mbar