2.0 tdci Galaxy not starting. ADAC said fuel pump not working but not clear!

[chabadav]

After changing the oil and filter went for a 15 min. run and all good.

Left on street for afew days and then it would not start - absolutely no sign of life and I suspected a fuel issue.

Called ADAC and the mechanic told me the fuel pump in the tank was not working and needed to be replaced. It started fine when he put starter spray into air intake but then cut out immediately.

I did a little research and quickly realized the WA6 2.0 tdci from 2007 does not actually have a tank fuel pump - only a tank level sensor. The high pressure fuel pump attached on the top right of engine is the only pump and presumably "sucks" the fuel from the tank.

I disconnected the fuel return line above filter and attached a suction line. The diesel fuel did come through and only a few tiny bubbles visible in clear fuel line from filter to pump. Still did not start so I presumed HP pump was indeed defect.

Got a used one (refurbished Siemens/VDO 5WS40380) for 200 EUR and today replaced it. It did not help!

Before trying to start I tried to suck the fuel through the fuel lines and new pump by again putting a vacuum on return line.

Diesel came through the clear fuel line from filter to pump and no eventually air bubbles cleared, so I presume all is air tight and no leaks downstream to tank.

I also unscrewed the HP line screws attached to all 4 injectors and turned over the engine but did not see any fuel coming out of pipes there.

This makes me think the pump is perhaps not being rotated by the overhead cam shaft. Can this happen?

[chabadav]

just read a post by "pointer" from last year where the RAC also pointed to a bad in-tank fuel pump (there is not one!), however the fuel pressure sensor fitted to the high pressure common rail (I think that's where it is fitted) was faulty. I have ordered one (only 20 EUR) so I will see if that works.

[Solentview]

Sorry if I am a bit 'late on duty' with this, but a neighbour had a similar problem, and it turned out to be faulty immobiliser electronics cutting off the fuel supply. A sniff test at the exhaust pipe suggested no fuel, and this was later confirmed by the AA man checking diagnostics and fault codes. His was petrol, but I suspect that all these injection systems, petrol or diesel, are controlled in the same manner.

[chabadav]

Sorry if I am a bit 'late on duty' with this, but a neighbour had a similar problem, and it turned out to be faulty immobiliser electronics cutting off the fuel supply. A sniff test at the exhaust pipe suggested no fuel, and this was later confirmed by the AA man checking diagnostics and fault codes. His was petrol, but I suspect that all these injection systems, petrol or diesel, are controlled in the same manner.

Thanks a lot for the reply! I am not sure what the "Immobiliser electronics" is, however would perhaps fit. However no idea what I can do to try and repair this.

Latest update from today:
After replacing both the fuel pressure sensor and the HP fuel pump, connected everything up again and sucked the diesel through via the fuel return line. Sill absolutely no sign of life when turning over!
I checked error codes (DTC codes) using FORScan and the following came up for the Powertrain Control Module (PCM):

P2505:00-25   ECM/PCM Power Input Signal

P0A09:00-25   DC/DC Converter Status Circuit Low

P0562:00-25   System Voltage Low

P0191:00-25   Fuel Rail Pressure Sensor Circuit Range/Performance (Bank 1)

For the last code it states that possible causes are:
1. An electrical fault in the Pressure Control Valve circuit
2. Electrical connectors not fully engaged
3. Wiring Harness Short to Battery or Short to Ground

Anyone with any ideas / suggestions on how I may solve this by myself before resorting to towing to local Garage.

Thanks a lot!

[johnnyroper]

Looking at those codes I would hazard a guess there is either a fault within the PCM or it's lost a feed in to it.
Given you have no fuel at rail (assuming that's still the case) it suggests the HPFP isn't receiving supply to the fuel control valve.

[chabadav]

Looking at those codes I would hazard a guess there is either a fault within the PCM or it's lost a feed in to it.
Given you have no fuel at rail (assuming that's still the case) it suggests the HPFP isn't receiving supply to the fuel control valve.

Thanks for the idea, which sounds reasonable. Are you referring to the electrically controlled device sitting on top of the Siemens fuel pump, and that it may not be getting power/signal from the PCM? I guess I could check that with a voltmeter if I unplug the connector. Or is it the one at the bottom of the pump, which is really difficult to get to?
Is it difficult/expensive to replace the PCM?

[johnnyroper]

Not sure which one it would be on a Siemens pump as I have only really had dealings with Bosch cp4 pumps. And yes my suspicion is the control valve is not receiving power considering the faults in the PCM.

The physical replacing will be fairly straightforward but it would need coding to the car, if it is faulty I would be inclined to try ecu testing to see if it can be repaired as it would be plug and play then.

[chabadav]

Thanks again for your help.
I do not think it will be the valve on the pump itself, as I replaced with a reconditioned one (which included the 2 valves).
My guess is that it is either the wiring/connectors that attach to the valves or perhaps the ecu unit itself. If I cannot get it to work after checking/cleaning the wires and connections I can get a used ecu for around 100 EUR, but I presume that would also need to be coded for the engine?

[chabadav]

so I just removed and tested the fuel pressure control valve sitting on top of the High Pressure Diesel Fuel Pump and it appears to be working properly. Hooked up to 9V battery and the solenoid switched easily and freely. Cleaned up with diesel fuel pump calibration fluid (Busching).

So I suspect this points to the PCU/ECU being at fault, as the connector also seems fine. Would it make sense to just order a used ECU from the same model/engine/year and try? available for between 100 and 150 EUR.