TD4 HP Pump questions?

I have an issue with a non starting 03 plate Freelander TD4..

I have searched and read about many of the possible non start scenarios, but none seem to fit this..

scanned with Snap-on Modis it reports P0190 Fuel Rail Pressure Sensor.

Further investigation shows that when the supply pipe from the high pressure pump is disconnected from the rail there is a flow of diesel with ignition on.. this never increases when turned on the starter.

another (second-hand high pressure pump was fitted, but the car still wont start or attempt to, not surprising really because if the pump to rail connection is disconnected there is no fuel flow at all..

the single priming pump (being a later model) is supplying fuel to the high pressure pump and the high pressure pump is turning (viewed through the sprocket tool hole when cranking), but not a bit of fuel in the rail.

My question finally is do we have two dead pumps but both dead in a different way (possible I guess but unlikely), or is there some electronic override to prevent the high pressure pump creating pressure?.. if yes how & why does this work as the pump is primed and turning..
I've also read that if the rail pressure sensor is faulty it can prevent starting but the car will start if unplugged, I've tried both but no joy not surprising as I only have lift pump pressure with original pump or no pressure (or fuel in rail) from new (second-hand) pump..

original pump has be sent for testing (Feather diesel) so if anyone has any other ideas I can try with the new (second-hand) pump in themean time I'm all ears, thanks jon

zytec said:

I've also read that if the rail pressure sensor is faulty it can prevent starting but the car will start if unplugged, I've tried both but no joy not surprising as I only have lift pump pressure for original pump or no pressure from new (second-hand) pump..

original pump has be sent for testing (Feather diesel) so if anyone has any other ideas I can try with the new (second-hand) pump I all ears, thanks jon

Click to expand...

The connection on the fuel pressure regulator on the chassis is the one you need to pull off.

If you pull the connector off the injector rail it wont start.

Thanks for the quick reply..

I'm still not understanding how it can know if it has or hasn't enough rail pressure (i.e. a rail sensor fault) when there is no fuel in the rail or what if anything other than a dead pump can cause it to have no pressure when the high pressure pump is being supplied with fuel from the lift or priming pump and is turning (when cranking)

surely the sensor on the chassis is lift pump pressure? if yes would this being faulty cause the ECU to stop the hp pump creating pressure via the only electronic part (pressure governor on the rear of the high pressure pump)?

If yes it still doesn't explain why I have two pumps doing different things

still confused

have you tried staring it with easy start, as leaking injectors a common problem not allowing the rail to pressurise. If it start with easy start and runs ok but will not start again on key will be a injector fault

Yes it will start on easy start, and run (but only until it's used it up).

I had considered injector issues but as said there is no rail presure above the minimal lift pump presure (with origanil pump), and none at all with new (second-hand pump) no fuel in common rail

for there to be injector bleed issues I'd expect to see most if not all of the 28,000 psi

for some reason I'm getting no high pressure created and really wondered what electronic parameters govern this if it's not two dead high presure pumps?

right ok, it need 1800psi to start on cranking, prior to 28000 running pressure.
There are issues with the plug onto the rail pressure sensor, Lr do a modified plug and wire that you have to connect to the ecu, but if you clean the sensor and plug using a contact cleaner it may solve your problem

Ok thanks but does it make sense that there is no pressure in the rail at all? (actually no fuel in the rail with one pump)

the supply pump (lift pump) to the high pressure pump is flowing at a fair rate, but haven't tested it for presure, however it's working

again both High pressure pumps we have are doing different things, which is puzzling..

not really questioning anyone's help here just want to try to understand how it all works and why I'm not seeing any high pressure pump output. I can understand it not starting with a leaky injector but do the electronics prevent the high pressure pump creating any rail pressure at all if it thinks there is a low pressure pump issue, (even if there isn't in reality)

Ok pull the connector on the low pressure sensor on the rh bulkhead as you stand in front on hippo as see if it starts on limp home mode

Hi I have had a breakdown today with my 2002 td4, drove to local supermarket no problem tried to start car. engine turing over normal but no attempt to start.Called AA came back about an hour later car starts straight away switched off would not restart. Checked fault diagnosis on laptop indication faulty fuel pressure sensor, checked conections,tested for leaking injectors none. Car starting and running ok at momment but recommendation to investigate further and probably replace sensor.

This is well worth a read for TD4 diagnostics...

75ZT HOME

cheers

Blippie

Blippie said:

This is well worth a read for TD4 diagnostics...

75ZT HOME

Click to expand...

Blippie said:

cheers

Blippie

Click to expand...

It certainly is a good read. Many thanks Blippie.

No problem. Useful isn't it?

Cheers

Blip

The high pressure pump has been checked and is apparently ok, have tested the low pressure pump and it is supplying more than the required 1.9 bar, but still same symptoms no rail pressure at all.. does anyone know what if anything electronic can prevent the high pressure pump creating pressure when it is turning and being supplied with fuel from the low pressure pump? is there a sensor or circuit that will stop the pump creating rail pressure at source if so what.. I'm about ready to try a can of unleaded and a box of matches to solve it once and for all

zytec said:

The high pressure pump has been checked and is apparently ok, have tested the low pressure pump and it is supplying more than the required 1.9 bar, but still same symptoms no rail pressure at all.. does anyone know what if anything electronic can prevent the high pressure pump creating pressure when it is turning and being supplied with fuel from the low pressure pump? is there a sensor or circuit that will stop the pump creating rail pressure at source if so what.. I'm about ready to try a can of unleaded and a box of matches to solve it once and for all

Click to expand...

sounds like it might be worth testing your injectors.

Maybe but I can't see how injectors leaking would give me no (zero) fuel in the common rail, no output at all from the high pressure pump, (except lift pump presure).. to me it appears an electronic control is stopping the pump from being able to make high pressure, but I have no idea what is able to, how or why, nor can I find anyone with a similar problem.

Great to hear a conclusion to a fault