Losing fuel pressure under boost??

[8man1320]

Walbro 190 installed, -6an feed to the fuel rail, 550 injectors, T28, fuel pump rewired.

Base fuel pressure at 44 psi, good voltage at the pump. As I come into boost my fuel pressure comes up to where it should be (about 54/56 psi) then drops after about 1 second. Car has never done this before. I have thought about this for days, but cannot seem to figure it out. Some ideas would be great. Thanks in advance.

 

[GVR4592]

Have you checked for boost leaks in the line?

 

[8man1320]

In the line to the FPR? No, but I'm pretty sure the lines are in good shape.
I will check though. Anything else that may be causing this?


I have now checked for leaks in the lines from the intake to the fpr. Used my compressor @15psi. Nothing.
No fuel leaks either. I'm stumped.

 

[8man1320]

I replaced the fuel pump and installed the pressure gauge at the same time.
Car made good fuel pressure for two weeks then started this issue. A 190 should be enough for this, still puzzled.

 

[8man1320]

I have now removed the pump just to be sure that the o-ring is still o.k.
Lots of work just to check, need some ideas. PLEASE.

Bypassed the other wiring, pump straight to the battery was no difference.
High 13's on the voltage the whole time. Think my pump is screwed.

 

[8man1320]

Anyone else, before I buy a new pump??