I just wired up my stewart warner electric fuel pressure gauge this weekend. It works but the pressure on the gauge doesn't match the pressure that I have on my under hood gauge. I teed the sender into my gauge that was already under the hood off of the schrader valve. My electric gauge reads 30psi and the underhood reads 38psi it idle. I did leave the schrader valve in, could that be my problem? Could the schrader valve be restricting some flow to the sender so it wont get an accurate reading, but I also have it teed in front of my liquid filled gauge.