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Discussion Starter · #41 ·

The answer to your question is yes, but not as I hoped to.

As I said my fuel pressure wasn't responding how it should (a bit of confusion induced by the way the OT-2 monitors didn't help) and AB very kindly sent me a spare regulator to try, meanwhile I silver soldered a gauge fitting into the end of the fuel rail for monitoring purposes.

While ABs regulator changed things, I suspect I managed to damage it as it was then at a constant 4.5 bar indicating that the in tank regulator was constantly feeding the fuel rail with full pressure & the fuel rail regulator wasn't regulating, so I guessed that it was goosed.

I then bit the bullet & got a new OE regulator & I now get coppers under 3.5 bar at idle & around 4.5 at full revs, so it now works as it should if that helps.

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I have a similar R53 fuel system pressure issue and wondered if anyone here could help. My car is running 550cc injectors properly scaled.

My max fuel pressure measured using a mechanical and electronic transducer is 56/58psi @ 17psi boost 6-7k revs - connected to the rail end on the -4n connector schrader valve removed.

I've changed:
New OEM Filter
New OEM Rail Regulator
New OEM Pump, then replaced with Lohen High Flow pump - 290l/hr open flow (vs 250l/hr OEM)

I know I should have 3.5 *14.54 (rail) + 17psi (boost) - 66/67 psi at WOT max revs, but can't figure out why I don't have this pressure. Could it be the filter bucket regulator in the LHS tank assembly?

My idle pressure is correct - 42/43psi and my key on is always 50psi or more.

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