I have installed a fuel pressure sender for a speed hut digital fuel pressure gauge which now resides in my dash. I really like it. Problem is it reads 38 lbs at start up then slowly drops to 22 or 23 lbs. I burn 20 gallons of gas on yesterday's test run and all seems good except for the fuel pressure. I have been warned and have a nagging feeling when I start to spin upwards of 6000 rpm this could be a real problem. What do you think it is cause. 1. Poor supply to the pump. 2. Regulator not allowing pressure to build to prescribed 39 lbs. 3. Poor calibration of fuel sender unit.???