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Fuel Pressure drop

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Hello guys first time posting. I have a Haltech platinum pro ecu with an rb26dett engine setup. I was in the process of doing a road tune when I noticed my fuel pressure drop and then go back up. I've checked all my fuel connections from tank to fuel rail. In tank I have dual aem fuel pumps both new. I have tried to duplicate the problem by I have not been able to. Can anyone point me where I could look?

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Is the ecu boost reference pre or post throttle?

I assume the fuel reg is from post throttle reference rail and the fuel pressure channel is rail relative to boost?

Without knowing all your plumbing and assuming that 50% throttle is close to reality and isn't actually near wide open I'm guess that you are running boost compensated alpha-N or AFM tune and the regulator reference line is seeing the differential pressure drop across the throttles that increases with flow (rpm/time in the log) and consequently the differential fuel pressure drops with rising engine speed on a partial throttle.

If your boost sensor and reg are seeing the same reference line, although you might expect a few PSI regulator sag from low to high fuel demand I'd say the pumps aren't keeping up due to total line resistance/demand and possibly voltage drop due to undersized pump wiring or increased electrical loads and the alternator not keeping up. Did you log system voltage? Do tge pumps have good power supply?

If either or both MAP and fuel pressure sensor outputs are a bit off true it can do strange things to calculated difference channels depending on where they both are in absolute pressure too but that is a big shift. Guessing it ir reference position/throttle restriction related.

The ecu boost reference and fuel reg is post throttle and I'm tuning using alpha-N. I did log power supply. The wiring to the pumps are new.

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Have you checked the voltage to the pumps earth ur multimeter to the earth of the pump make sure ur getting the same voltage as when u earth to the body

Factory they have the voltage control shit so pump only gets 11 volts to spin it slower at idle we generally run a 6mm power and a 30amp relay per pump and ground the pumps th o the body directly and control relays via ecu earth

We have just had a massive issue that we think we have sorted now on a 33r thats taken weeks of trial and error so i feel ur pain best of luck

I'll get on that asap. I'll let you know the results, thanks.