Not the typical Fuel Issues

[DeputyDiesel]

So I thought id give the old girl a little treat.

New fuel pump.

The company that builds it will remain un named until I have this issue sorted out.
But for reference purposes it is a factory replacement flows 150gph should do 50psi factory setting and up to 70 with the adjustable regulator thats built into the unit.

Here is my Issue.

The pump will only make 40psi.

It is not sucking air anywhere. Nor is it leaking fuel.

With my RR setup I had been running the Ford factory pump at 65psi.

Yes I have adjusted the RR system no less than 1000 times. It will only return fuel to the tank. When the RR is set under 40psi.

Yes I have adjusted the regulator on the new fuel pump itself.

By the way was bottomed (Full Pressure) when i got it. And the O rings their tech told me to check on the regulator were shot. Lucky for me the pump comes with replacement o rings. Just didnt think id need to do them before the truck left my shop!!!

Light Driving and idle it stays at 40psi. WOT it drops to 30. checked with 2 different gauges.

The power supply to the pump is perfect. The ground Is perfect.

I really cant afford this down time right now. Need the truck to Move!! 40PSI scares me. However it 1/2 supply and 3/8 lines to the heads. Might be enough volume?

So im looking for some fresh ideas because im all out. Maybe some of the RR return guys that run after market lift pumps have had issues?

But im thinking the pump is no good.