A2 1.6fsi fuel starvation problem

Does anyone know if the fuel pressure controller (the one on the fuel rail) should constantly pass fuel when on vcds it indicates initially on start up reducing 29% at 99.8brg to 23% at 58.9brg then drops to 0% with pressure remaining 58.9 I have detached the fuel hose and fuel definitely flowing at 0% I am trying to rule out if I need a hi press fuel pump
Any help greatly appreciated
I believe if the fuel pressure does not reach (or maintain) it's set-point, you will get an error code indicating such. ~60 bar sounds about right, what problems are you getting?

Only error code is for fuel pressure regulation control exceeded
Car takes 4 2 or 3 attempts to start when cold initially normal revs then dies once running ok error only occurs on startup once running no error occurs I have put in place an adjustable regulator between the fuel rail controller outlet and the in situ regulator increased pressure to 8 brg so holding fuel back in the fuel rail car now starts first time temp measure untill I decide do I change the hi press fuel pump (easy option ) or the controller
Although the pressure is there the fuel flow may not be sufficient if I go to max revs the contoller does not open so there is no excess fuel for the controller to open? Is this due to it passing or the fuel pump


A2OC Donor
Fuel pressure sender (G247) is located on the intake manifold lower section and is screwed into the fuel rail.
It measures the fuel pressure in the fuel rail.

Signal utilisation

The engine control unit utilises the signal from the fuel pressure sender for map-dependent regulation of the fuel pressure in the high-pressure fuel system.

This is how it works

Fuel flows out from the fuel rail into the fuel pressure sender.
- The steel membrane is only slightly deformed at low fuel pressure, with the result that the resistance in the strain gauges is high and the
signal voltage is low.
- The steel membrane is heavily deformed at high fuel pressure, with the result that the resistance in the strain gauges is low and the
signal voltage is high.
The signal voltage is amplified by the electronics and sent to the engine control unit. The fuel pressure is regulated by the fuel pressure
regulating valve.

Signal failure strategies
If the signal from the intake manifold pressure sender fails, the fuel pressure regulating valve is activated by the engine control unit at a fixed value.


A2OC Donor
Ok! I misunderstood fuel pressure controller, you mean the fuel pressure regulating valve!

The fuel pressure is adjusted to between 50 and 100 bar by the fuel pressure regulating valve (N276)

The task of the fuel pressure regulating valve is to adjust the fuel pressure in the fuel rail irrespective of the injection quantity and pump
delivery rate.

This is how it works
If deviations from the setpoint pressure are detected, the fuel pressure regulating valve is activated by a pulse-width modulated signal
from the engine control unit. As a result of this, a magnetic field is induced in the magnetic coil and the valve with the valve ball lifts off the valve
seat. In this way, the flow cross-section to the return line is changed depending on signal size, thus altering the discharge rate and regulating
the fuel pressure.

Failure strategies

The regulating valve is closed in de-energized state. This ensures that sufficient fuel pressure is always present. To protect the components
against excessively high pressures, a spring operated mechanical pressure limiting device is built into the fuel pressure regulating valve. It
opens at a fuel pressure of 120 bar.
Thanks for info
When n276 is closed is fuel still supposed to flow or is it passing due to damaged o ring etc n276 only opens at start up. On idle 0% all the way to max revs again is this due to passing or hi press fuel pump so would never achieve the 120brg


A2OC Donor
When N276 is in passive state (no electric signal), it shall be closed. Except if the pressure exceeds 120 Bar and the valve is opened mechanically.
With car running fuel pressure at approx 100brg n276 is showing closed car will only achieve 80mph with the adjustable regulator fitted (temp measure until I sort it) 100mph so there is a lack of fuel
Control valve N276 passing or fuel pump not sure which might just change them both,don't fancy a day on car again at the moment
I had problem with fuel starvation above 3000 rpm, but not as severe as you describe. The only error I had was "Fuel range exceeded", Intermittent.

My assumption was the sensor but I replaced both the valve and the pressure sensor while the intake manifold removed. The fault disappeared.
It does sound like the N276 is passing, if it has an intermittent problem and is being lifted at 120bar, it would not surprise me if this has damaged the seat of the valve if this has happened repeatedly. I wouldn't expect the valve to be passing when it is showing as shut, but I don't know for sure. May be worth trying a 2nd hand unit instead of new to see if this helps without spending the £££