Need help with fuel pressure issue

[7MGTEsup]

Well here's the story

I have just fitted a gss341 walbro pump and now I have strange fuel pressure issues.

With the stock pump in place and running a constant 12v I adjusted my pressure to 36psi no vacuum and it ran solid and stable.

Now with the gss341 at 12v I have 46 psi with the engine running (no vacuum), but and here is the confusing part if I jump fp b+ its 34 psi

I just need someone else to sanity check whats going on, I thought jumping fp b+ gave you 12v to the pump so the fuel pressure should be the same ( or at least it was with the stock pump.)

 

[7MGTEsup]

No one have any ideas????

 

[dbsupra90]

without the car running, your voltage is lower to the pump.

did you bypass or drill out the J tube on the hardline return?

 

[7MGTEsup]

without the car running, your voltage is lower to the pump.

did you bypass or drill out the J tube on the hardline return?

Yes I did the j tube mod, I put a DVM accross the fp b+ terminal and it comes back as 12v. I think it might be my pressure regulator not having enough adjustment to lower the pressure with the higher flowing pump.