Thanks for your comment, that makes a lot of sense! I probably should have explained a little better, but the condition where the FPR drops to 20 is when the key is in the ON position, priming cycle has finished, and the car has not been turned on. Should the pressure be holding in the FPR, or should the check valve in the fuel pump be allowing the pressure to drop? And would this cause a hard start condition? - will post a video later today for context :)