I purchased a 255 LPH fuel pump that has the check valve right in the output port. I don't use the pulsator anymore and have been using a braided piece of fuel hose in its place. The braid is metal so it requires a fair bit of torque to wind down the clamp. Anyway It turns out I over tightened it and the check valve was not working making starting the car difficult. I found this out the hard way. I deformed the pump outlet. Those of you who have done this job know how fun it is. So in two days I had the tank out twice. I fixed the deformation in the outlet and the valve now works as it should.

So what I'm saying in a round about way is: Don't over tighten the coupling clamps on the pump, especially if you have the one with the check valve visible in the outlet port. Once you install the coupling, blow through the hose and make sure air does not come out the inlet side of the pump.