Start problems 944

hello professionals, have a problem at which also the workshops bite out the teeth. for half a year I have started problems if the car has stood for more than two days. now I am so far that after four days the motor does not start at all. the petrol pump I have bridged the petrol pressure is okay ignition spark is because the battery is new the compression at 11.5 bar I guess it’s due to the control for the injection system. who can help me with literature, so that I can read which sensor is responsible for what. or which voltages I have to measure where and what can then be defective. I am grateful for every tip greetings hans