HSV.ETA

I have a mildly modified 2ltr mk1 that has been cutting out and missing at high revs. I have changed all the usual bits and out of curiousity I quickly installed a fuel pressure gauge to check what the pressure was (installed in line just before the fuel line connects to the the standard carby). The car has an electric pump and the reading while generally running around was only around 3-4 psi, is this to be expected or should it be higher? When the engine is being driven harder the pressure drops all the way to zero then picks back up again (to around 3-4 psi). I'm guessing that this isn't good and might be causing my cutting out problems, what do you guys think? What sort of pressure should the electric pump produce (the gauge should be reading correct as its brand new)? Do these readings mean my pump is stuffed? Thanks for any help.

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1965 XP Falcon sedan (soon to be a 250 crossflow and T5)
1986 XF Spac Sedan, EFI, T5, lowered, with a few more mods to come.

460Fairmont

The electric pump will need to be between the mechanical pump and the carby or it will have no effect. 3-4psi is a bit low most are around 5-7psi. If it's the standard carby you may only need the standard pump. Have you tried a new standard pump?

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XD Fairmont, X-COP, BIG BLOCK still in bits
Injected RS2000 2 door (new toy)
EA Falcon, MPFI, 16in XR6 wheels,
2x1000W 12in subdoofers, splits,
TE cortina,Toyota Supra,TD cortina