Does anyone know if the T-Rex has a check valve in it too restrict fuel back flow like the in-tank pump does?

I ask because since removing my T-Rex my FP will not stay up when I turn the key to the on position. It comes all the way up and almost immediately drops all the way back to zero.

I am trying to determine if my leak down is from the Walbro. If the T-Rex does NOT have a check valve then removing it at the same time as the problem starting is coincidental. If it does have a check valve then I will assume the Walbro was bad from day one and the problem was masked by the T-Rex's check valve. That will **** me off because I'm sure I've had it too long to return

There's still a few other things I need to look at but my AFPR is also fairly new so I don't think that's it.

 

the t rex dont have a check valve in it, check you regulator, I was having the same problem and just put an accel adjustable regulator on mine it fixed the problem.