LS1 fuel pressure bleed off after pump replacement

[VR38]

Replaced my fuel pump and it fixed most everything but within days the hard starting crept back in, one month later I installed a gauge on the rail, clamp the fuel line after shut down and pressure holds, take the clamp off and pressure drops about 10psi almost immediately.
Spare parts want me to remove the pump to send it back for testing and possible replacement at their discretion.
Also, notice that ever since Ive had the car there is no pressure release when removing the filler cap.
Anyone got any ideas?
Im thinking damaged hose on module or defective regulator.

 

[VR38]

After doing a bit more reading it may even be a faulty pump.
Far out, car will be off the road for weeks while they send it back for testing...

 

[EYY]

The regulator is inside the fuel pump module. Either the regulator is damaged or there’s a leaking injector

 

[VR38]

I'm on my third pump now, two returned to AFI and now the third Delphi is also losing pressure and causing hard start issues.
Anyone got some experiences to share?
Thinking of installing non return valve in line...

 

[07GTS]

need to find out if its actually the pumps non return not working or maby the regulator isnt closing fully allowing it to leak out, if ur on your 3rd about to be 4th pump for same reason that means something isnt right

 

[VR38]

Im not keen to clamp off the two nylon lines at the tank to test the pump return valve and reg.
Any suggestions or does anyone have a copy of Holdens test procedure?

 

[Dylan kingswood]

Is there a pressure reg on the rail to the return line or is it on the in tank pump ?

 

[VR38]

It's a complete module I have been replacing in the tank, sorry for any confusion using the wording "fuel pump", it's an omission form an old school guy...
There is no issue with the injectors.

 

[Dylan kingswood]

YEah but is there a fuel pressure reg on the fuel rail? sounds to me that a reg has failed and since your on your third pump there must be a reg in line jammed open

 

[VR38]

Yeah but do you even read bro?

Im on my third fuel reg...