VWT6 CXEB NON START After rebuild (2017)

[Dellmassive]

The bleeding might be my next course of action.
l rebuilt the engine so know it's not the grease issue.
New seals fitted then replaced back with the correct cylinder

assuming you used VCDS to use the FUEL PRIME feature,

to run one/both lift/prime pumps for 60sec each.

to get the fuel system primed properly?

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++++++++++++++++

 

[Dellmassive]

Yeah it runs with spray.

Well chuffs away for a few seconds then stops

so you have a fuel problem then?


if you keep spraying will it keep running?



+++++++


sounding more like a fuel problem to me?

 

[DXX]

Try this

Fixed , Sloved !
Hello, thank you all for the good information !
How we did get the T6 runnnig:

Removed the rail sensor. (this to increase rail pressure +300bar and also this automaticly open and close the injectors)
At the same time, opening the nuts from the pressure lines to the valves.
By these 2 things the possible stuck air could breed out of the system.


Thank you again all !

Dries VB

 

[Dellmassive]

Here's a log of the previously suggested values to check.

just a quick graph @mmi style

rail pressure vs time 1-8seconds

rail pressure rises to 40000kPa


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looking over here:

Start up fault

Really happy with the help so far - have never received any remotely useful input from the dealership. But in there defence they never observed it faulting first hand only my videos. VCDS has been fantastic so far - only my inexperience limiting it. Reading the comments on the time stamps does...

www.t6forum.com

we get around 30000kpa at startup.


...

rising to 89000kPa when running under load,



...






so can you get a better startup data set,

have a look at @mmi instructions here - Start up fault

and post so we might get a better idea.









............







but having good rail pressure doesnt mean that the injectors are firing,

so its rail pressure first - then we look into the injector fire + glow plug comands.


.

 

[mmi]

assuming you used VCDS to use the FUEL PRIME feature,

to run one/both lift/prime pumps for 60sec each.

to get the fuel system primed properly?

++++++++++++++++++
View attachment 238617

++++++++++++++++

Steps with VCDS:

[T6_measured] 01-Engine - Built-in test for Transfer fuel pump

A quick DIY way to test fuel lift pump's basic functionality. The test takes advantage of engine's fuel high pressure sensor (in fuel rail). Running the lift pump continuosly makes the pressure eventually "leak" through high pressure pump and can be detected by fuel pressure sensor. As a side...

www.t6forum.com

 

[DXX]

Steps with VCDS:

[T6_measured] 01-Engine - Built-in test for Transfer fuel pump

A quick DIY way to test fuel lift pump's basic functionality. The test takes advantage of engine's fuel high pressure sensor (in fuel rail). Running the lift pump continuosly makes the pressure eventually "leak" through high pressure pump and can be detected by fuel pressure sensor. As a side...

www.t6forum.com

But the air needs to be vented.

 

[cottya]

Thank you all. I need to get a newer VCDS. The one I have wont let me cycle the fuel pumps. I'll get the better data set tomorrow and put it online.

I am also going to attempt to remove any trapped air by removing the charge air cooler and bleeding up to the injectors.

I'll let you k ow how it goes...

 

[n10n]

Also please note the workshop manual says bleeding must be done for at least 3 minutes for the hpfp to have enough fuel and not run dry

 

[mmi]

But the air needs to be vented.

Well, that's the question I asked at the garage - was told that it bleeds the air through injector's return flow port. I haven't verified that by myself but I have been lucky to witness immediate startup after fuel filter replacement and almost immediate startup after injector replacement.
EDIT: link correction

[T6_measured] Injector failure

Keyword “loud knocking metallic noise from engine”. VW has published in September a service note which can be found with vehicle's VIN. The sound clips from my engine (150PS, EU6) with comments on 21 Oct 2017 in thread Tick over noise EDIT: audio files from the thread copied here as...

www.t6forum.com

 

[DXX]

Thank you all. I need to get a newer VCDS. The one I have wont let me cycle the fuel pumps. I'll get the better data set tomorrow and put it online.

I am also going to attempt to remove any trapped air by removing the charge air cooler and bleeding up to the injectors.

I'll let you k ow how it goes...

Carista will perform this function.

 

[DXX]

Well, that's the question I asked at the garage - was told that it bleeds the air through injector's return flow port. I haven't verified that by myself but I have been lucky to witness immediate startup after fuel filter replacement and almost immediate startup after injector replacement.
EDIT: link correction

[T6_measured] Injector failure

Keyword “loud knocking metallic noise from engine”. VW has published in September a service note which can be found with vehicle's VIN. The sound clips from my engine (150PS, EU6) with comments on 21 Oct 2017 in thread Tick over noise EDIT: audio files from the thread copied here as...

www.t6forum.com

The fuel rail would be full of fuel after a filter change and I suspect that it was almost full after an injector replacement. Just the HP delivery lines to fill and they are very small bore.
It’s not just the HPFP that needs fuel to lubricate, the clearances in the injectors are tight, injector damage can occur if fired dry for an excessive period.

 

[Dellmassive]

But the air needs to be vented.

according to VW its self venting, - provided that the fuel prime procedure is followed making sure the HPFP is full of fuel so that rail pressure builds straight away.

@mmi mentioned about venting via the return line,

i was told by the VW tech that the HPFP pressure is so high the air is compressed to microscopic bubles that travel through the system and vented back at the tank.



its mentioned again above in @n10n quote,

 

[Dellmassive]

@cottya

come join as a VIP,

then you have access to all the tech downloads . . . . .

VIP Membership

VIP Membership Information

www.t6forum.com

+++++++++++


then check these out.

Downloads

www.t6forum.com

eg:

T6 & T6.1 - Diesel Fuel Supply System Workshop Manual

Workshop manual covering fuel supply system for all diesel engined vehicles This document covers removal/installation of system components like tank/pump/filters etc and also covers misfuelling procedures VIP Membership is required to download...

www.t6forum.com

T6 - CAAC CAAB CAAC CFCA Diesel Engine workshop manual

VW workshop manual for the CAAC CAAB CAAC CFCA Diesel Engine Click the download button above to save this file locally.

www.t6forum.com

T6 Fuel Filter

Workshop manual excerpt for fuel filter replacement.

www.t6forum.com

SSP 564 - The T6 2.0L TDi

VW Self Study Programme, Document 564 - The 2.0 litre TDI Engine In The T6 The introduction of modern, particularly efficient Euro-6 engines represents a central feature of the new T6. All units are equipped with Blue Motion Technology as...

www.t6forum.com

...

 

[DXX]

The HPFP is a fixed displacement pump.

according to VW its self venting, - provided that the fuel prime procedure is followed making sure the HPFP is full of fuel so that rail pressure builds straight away.

@mmi mentioned about venting via the return line,

i was told by the VW tech that the HPFP pressure is so high the air is compressed to microscopic bubles that travel through the system and vented back at the tank.



its mentioned again above in @n10n quote,

View attachment 238632

Fixed , Sloved !
Hello, thank you all for the good information !
How we did get the T6 runnnig:

Removed the rail sensor. (this to increase rail pressure +300bar and also this automaticly open and close the injectors)
At the same time, opening the nuts from the pressure lines to the valves.
By these 2 things the possible stuck air could breed out of the system.


Thank you again all !

Dries VB

 

[Dellmassive]

The HPFP is a fixed displacement pump.

makes sense to me, that you need fuel (liquid) for the pump to work, and an airlock may form if it was dry.

so i can only assume that the return line and N290 valve must somehow allow self priming. . ?

it has its own fuel return line back to the tank, maybe that allows self air purging?


i dont know for sure as I've not been in this situation. . .




.................

++++++++++++++++++++++++

but what i have done is run the tank done dry till the engine cut out from fuel starvation. . .

i then run to the garage as we all do, and buy £1M quid for a 5ltr plastic fuel can,

then fill with 5ltr of derv, then back to the van,

put it then crank the engine hard until the battery run flat - it didnt start. !!!!

+

called the AA, who arrived and said the fuel prime pumps needed to be run after a run dry,

so while he had the battery charging he done the laptop thing and run the fuel pumps, (mine had two, one in the tank and a second one in the engine bay)

then after that it took 3 or 4 goes and the engine sprung into life.

this was on my MY11 T5.1, but basically the same on the T6.

the lesson i learned was:

A - dont let a T5-T6.1 run out of fuel

B - if you do, make sure you have VCDS or Carista handy to run the lift pumps.


..








.

 

[cottya]

I'll let you know how I get on working g through the things suggested.

I have the tech docs already thanks.

 

[Dellmassive]

I'll let you know how I get on working g through the things suggested.

I have the tech docs already thanks.

though, its Still worth joining as VIP for the input from the forum.

go on, you know you want to.

if anything it helps keep the forum Advert free. - that alone is worth £12.99

 

[DXX]

makes sense to me, that you need fuel (liquid) for the pump to work, and an airlock may form if it was dry.

so i can only assume that the return line and N290 valve must somehow allow self priming. . ?

it has its own fuel return line back to the tank, maybe that allows self air purging?


i dont know for sure as I've not been in this situation. . .


View attachment 238641View attachment 238642

.................

++++++++++++++++++++++++

but what i have done is run the tank done dry till the engine cut out from fuel starvation. . .

i then run to the garage as we all do, and buy £1M quid for a 5ltr plastic fuel can,

then fill with 5ltr of derv, then back to the van,

put it then crank the engine hard until the battery run flat - it didnt start. !!!!

+

called the AA, who arrived and said the fuel prime pumps needed to be run after a run dry,

so while he had the battery charging he done the laptop thing and run the fuel pumps, (mine had two, one in the tank and a second one in the engine bay)

then after that it took 3 or 4 goes and the engine sprung into life.

this was on my MY11 T5.1, but basically the same on the T6.

the lesson i learned was:

A - dont let a T5-T6.1 run out of fuel

B - if you do, make sure you have VCDS or Carista handy to run the lift pumps.


..








.

In the situation you described the HPFP would fail to raise pressure as soon as the LP lift pump lost supply to feed the HPFP. In this situation I would expect the fuel rail, injector pipes and possibly the injectors to still be full of fuel but unable to inject due to lack of pressure.

 

[cottya]

In the situation you described the HPFP would fail to raise pressure as soon as the LP lift pump lost supply to feed the HPFP. In this situation I would expect the fuel rail, injector pipes and possibly the injectors to still be full of fuel but unable to inject due to lack of pressure.

I had everything removed so there is definitely a chance there is air trapped air

 

[cottya]

Afternoon all thanks for your help so far. I have attempted to bleed the system where I could by cracking open the pipes. Each time I nipped the joints back up the engine would run for about 10 secs although lumpy. It's now back to original state almost starting but not quite.
The annoying thing is my VCDS is not allowing me to run the fuel pumps.
I'm getting refused by control module and other functions are telling me it's not supported in active session.
Can anyone let me know how to run fuel pumps for 3 minutes as suggested in the workshop manual. It would be nice to know I'm not selecting the wrong things.