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VW Touareg 2.5 2004 - Poor starting - Unresolved #

Posted by Joe O'FARRELL on February 10, 2015, 5:51 pm

Year of Manufacture *: 2004
Engine Size and Code *: 2.5 pd bac
( Optional) Fault Codes: no fault codes

Hi , got touareg 2.5 pd with 134k,
poor start if left overnight , intermittently, no fault codes, checked glow plugs and operation ok. Relative compressions ok,in tank fuel pump working and current draw ok, new mann fuel filter fitted, fuel quality ok, replaced injector seals as oil level was slightly high.
Haven't got fuel pressure tool to measure possible decay in pressure (yet) , any suggestions as a good tool for testing pd engines.
Car runs and starts fine after initial start up.
Camshaft and valve gear visually ok .
Any other suggestions would be appreciated
Thanks
Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on February 16, 2015, 2:19 pm, in reply to "VW Touareg 2.5 2004 - Poor starting #"

Update, managed to rig fuel pressure gauge between tandem pump and injectors, monitored fuel pressures and 8 bar at idle and increases when reved ok ref ERWIN.
But pressure does drop back to zero, in 1 second after switching off ! cant find any data for this ,just that there is a vw pressure gauge to test holding pressure.
After 4 days of testing finally got non start situation.and very low pressure on gauge at high pressure pipe,only after extended cranking did the pressure rise to 3 bar and starts ok again.
low pressure readings ok, 0.5 - 1 bar at filter, and both in tank waveforms ok 5-6 amps.
I pressume there is a check valve in the tandem pump to hold pressure tandem pump?
Ive dead headed tandem pump and pressure remains at 1 bar after switching off,if I clamp return at fuel filter pressure drops to zero, do the injectors leak or is there another valve in the rail/pipework, or am i missing something
Thanks

Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 16, 2015, 6:31 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Mark Carter

>>> I pressume there is a check valve in the tandem pump to hold pressure tandem pump? <<<

Yes there is, it is set to 1 bar, but there is also an internal throttling bore for bleeding the system of air, so the pressure will drop off quickly.

Are you sure you don't have an air leak that is letting the fuel return over night? what is the line pressure KOEO after a long rest?

What is the gallery pressure whilst cranking?

Mark

Modern cars, Its all wizardry and witchcraft

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on February 16, 2015, 7:44 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Joe O'farrell

Mark
Thanks for the info, I will try the KOEO test.
When the fault occurs the pressure in the pipe to the gallery is very low and takes 20 seconds to build up to 3 bar before it fires.
The fault will only seem to happen if the engine has reached operating temperature before being left overnight. When we started testing we couldn't get the fault as we were just driving in and out of the workshop.
Ive run a clear pipe from the fuel filter to the tandem pump ,to check for air, and air does appear in the pipe, only after we get the non start fault.
I will let you know how I get on with the other test.
Regards
Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on February 17, 2015, 7:15 am, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Jon Morgan

Can you move the clear line to the return line & see whats coming back from the head gallery during the starting issue, whilst monitoring the supply pressure?

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Ian Whitmore on February 17, 2015, 8:16 am, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Edited by board administrator February 24, 2015, 4:19 pm

Hi
Two things, have you checked the supply pressure to the tandem pump ? from memory about 6 to 8 psi.
Yes you can get leak off from the injectors.
The injectors sit inside a precise machined tube in the head. Sometimes the faces of this machining become very burred / scored and allow fuel by. If the injectors are slightly loose this happens.
Pop out the injectors and check.
Could be a new head and injectors if so.

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on February 17, 2015, 9:26 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Joe O'farrell

Thanks, Mark, Jon and Ian for the replies,
Much appreciated.
Ive done some further tests today.
Maybe the fault is developing.
I checked supply pressure to the pump, KOEO, and pressure did drop off from 1 bar to zero within 5 minutes.
But fuel remained in pipe but no pressure.
Dead headed fuel tank pumps at fuel supply at filter and pressure held ok.
Then tried clamping fuel pipe at tandem pump and pressure dropped off within 30 seconds.
Ran out of time today, but going to try and bypass fuel filter and check pressure drop. (Filter has feed and return , so may give odd readings ?)
Thanks
Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on February 18, 2015, 5:37 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Joe O'farrell

Update
Tested line pressure at different points in the fuel line supply and return.
Found pressure is held at 9 psi, in system when capped off.
Until the return pipe at the tank.
The return in the tank is not holding pressure.

I take it there must be a valve in the return side of the pump causing pressure drop?

Will remove pump tomorrow to check.

Thanks

Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 18, 2015, 7:10 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"

>>> The return in the tank is not holding pressure. <<<

No it doesn't and nor it should.

Restrictions generate pressure and there should be no restriction between the outlet of the pump and the tank.

I'm out and about tomorrow, but give me a shout Friday if you think it may help.

Regards
Mark

Modern cars, Its all wizardry and witchcraft

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on February 23, 2015, 6:01 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"

Mark

Thanks for the offer.

Car has gone back to customer for a few days.

Can someone tell me what the fuel pressure should be at the supply to the tandem pump,with the KOEO and switched off ?
As I had another PD diesel in today with NO starting issues, but it was a 1.9.
So I checked supply pressure at Tandem pump supply at filter and the pressure initially went to 6 psi and quickly dropped off to zero when switched off.

Regards

Joe

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 26, 2015, 7:38 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Mark Carter

That sounds about right, its only a pre-feed to the main pump.

Modern cars, Its all wizardry and witchcraft

Re: VW Touareg 2.5 2004 - Poor starting #

Posted by Joe O'farrell <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3685' width='330' height='300' border=0 style='border:none;'> on March 12, 2015, 11:20 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Joe O'farrell

Got car back,
Tested again and supply pressure ok when fault evident, but lots of air in return to fuel filter , with clear pipe fitted.
Still suspecting porous head as the fault only occurs, if the car reached operating temperature before being left overnight.
Thanks
Joe

Unresolved #

Posted by Joe O'farrell on April 16, 2015, 6:54 pm, in reply to "Re: VW Touareg 2.5 2004 - Poor starting #"
Edited by board administrator April 17, 2015, 2:00 pm

We suspected porous head or leaking injectors.

Customer did not want to go any further.

Thanks for your help.

Dont buy a blue 2004 touareg if its going cheap.

Joe

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