Does anyone have any idea when the primer pump inside the fuel tank on an Octavia II VRS CR Diesel is supposed to activate? Is it when the ignition is switched on? Is it when the engine is actually cranked? Is it when the drivers door is opened?

 

I have a HPFP failure as it is running dry within seconds of the engine running. Fuel is going through the system fine under diagnostics.

 

Appreciate any suggestions.

I am pretty sure it is when the drivers door is opened.

In my experience they have always run for a second or 2 when the ignition is initially turned on and then continuously once the engine is cranking and has started.

 

Don't forget there is another auxiliary fuel pump after the lift pump that supplies the HPFP.

 

When you say diagnostics, what diagnostics have been carried out? You need to check the lift pump is working first and then make sure the aux. p/p is working. Both can be run via VCDS

Edited 29 October, 20169 yr by SuperbTWM

Thanks for the replies. I am not technical - the car is with my brother in law who is an ex VAG mechanic but has now set up on his own. Unfortunately he is used to the PD engines and has little experience with the CR engine. All 3 pumps have been replaced and checked more than once but each time the engine is started the HPFP is starved, runs dry and fails.

Looks like I Can't post on this topic now until 10th November :-(

http://www.myturbodiesel.com/wiki/fuel-filter-replacement-2009-vw-jetta-golf-jsw-and-audi-a3-tdi/

Thanks "Owl" I will pass this link on to my mechanic and let you know if there is any feedback.

So as promised feedback from the mechanic:

 

"Fuel tank and all 3 pumps have been changed. All fuel lines have been changed an a new common rail has been installed. Fuel filter housing has also been changed. All fuel pumps have been primed with diagnostic until fuel has been coming out at the injectors. The engine has not been started until this has been done. Both the electric pumps work when priming with diagnostic.

The fuel pump relay has all the feeds when engine is cranking and running but no live feed to the primary pump when the ignition is on. Being mostly experienced with PD engines I know the primary pump engages when the ignition is switched on before starting. Can't remember if the CR engines are the same as I have not worked on that many and not had one in for a while"

 

Anyone have any thoughts?

I think it's when you unlock the car and open the drivers door.

Worth checking the door switch is functioning and the wiring harness in the door is in good condition?

Did you get to the bottom of this issue?