VW Golf 2.0 TDi BKD 2008 - Slow to start from cold, extended cranking - Fixed #
Posted by Jim Power on December 20, 2014, 8:24 am
Year of Manufacture *: 2008 Engine Size and Code *: 2.0 BKD ( Optional ) Scanner Used: VCDS ( Optional) Fault Codes: None
Hi all
This car is very slow to start from cold, extended cranking, but will start eventually, it has never failed to start. I have not witnessed this yet as the car only arrived yesterday.
The history is this guy bought this car privately for his daughter who is away in university, so it's a real pain to him to the point of talking of selling it.
It's had a new head gasket fitted due to losing coolant (still leaking, puddle on gearbox)injector seals have been replaced and a "relay" fitted, fuel pump I presume. Next step was to replace the tandem pump.
I checked the supply pressure at the filter inlet and showed 7 bar, I then checked the outlet and that showed 0.25 bar at idle, dissapearing when the revs were raised. Max pressure achieved from the tandem pump at this point was 9.5 bar at 3k revs. The filter looks brand new although what brand I cant say, but I did find a small amount of a florusent green substance on the filter!!
I suspected the delivery pipes were fitted incorrectly so changed them around. I now have a constant 4 bar at the filter outlet at any revs and 6.5 bar from the tandem at idle and 17.5 bar at 3k revs.
My question is, are these pressures too high? what max pressures should I have, is allowed?
Also worth mentioning when the car arrived it would idle at about 950-1,000 rpm, now idling steady at about 800 rpm.
Car has started without issue this morning, gauges still connected, pressure from tank pump immediately.
Sorry for the drawn out post, but to paint as clear a picture as possible.
Regards Jim.
Re: VW Golf tdi
Posted by Joe O'farrell on December 20, 2014, 6:33 pm, in reply to "VW Golf tdi " Joe O'farrell
Jim I presume its high mileage if its had a head gasket?
Maybe check in tank pump current draw, as they are prone to fail at high mileage .
Joe
Re: VW Golf tdi
Posted by Jim Power on December 20, 2014, 7:17 pm, in reply to "Re: VW Golf tdi " James Power
Hi Joe
Thanks for your response.
I have established today that the pipes were fitted incorrectly at the in tank pump which, I believe solves the slow starting issue (I hope)
I wasnt expecting values as high as I now have on both circuits. I read on a vag pdf that 11.5 bar was the max value for the tandem pump.
Also the test procedure states that "max 1.3 bar air pressure should be applied to the tandem pump" for testing, so a bit confused as I have an average of about 5 bar fuel pressure at the tandem inlet.
Regards Jim.jim power
Re: VW Golf tdi
Posted by Chris Angus on December 22, 2014, 10:30 am, in reply to "Re: VW Golf tdi "
Just looked this up on elsawin.
Tank fuel pump delivery pressure should be 0.5bar at idle and 0.25bar at 2500rpm minimum, so needs testing in curcuit when running. fuel flow of 1 lire per 30 seconds. Current 7.5A max
If you have 5 bar at inlet it looks like you're getting the full pressure the in tank pump can supply, could it have a restriction on the return to tank line??
Pressure from tandem pump should be 10.5 bar minimum at 4000rpm.
There are no mention of maximum pressures.
If you have a fax I can send the docs.
Chris
Re: VW Golf tdi
Posted by Jim Power on December 22, 2014, 7:18 pm, in reply to "Re: VW Golf tdi " James Power
Hi Angus
Thanks for your reply.
The owner informed me today that the tandem pump had been changed, news to me. I got him to bring on the old one and I changed it back. Made no difference but I now know where the green substance came from, sealer on the pump.
I have no restrictions in the fuel lines and I get 1.5 litres flow from the electric pump.Deadheading the pump gives 7.5 bar. I'm not concerned about the tandem pump pressure as I believe if I sort out the low pressure side that will be ok.
This has the fuel filter with five screws on top, 4 connections. I have 4+bar on three and 1bar on the tank return. The filter head must have some type of pressure regulation, otherwise I beleive the fuel would just return to the tank.
My theory is, with the fuel lines reversed at the pump for some length of time, the filter head was damaged, so I will try to get a new one tomorrow.
Let you know how that goes. jim power
Re: VW Golf tdi
Posted by Chris Angus on December 22, 2014, 9:22 pm, in reply to "Re: VW Golf tdi "
Ok, let me know if you want the docs, it shows the positions of the pipes on the filter and in tank pump, just so you can double check.
Fixed #
Posted by Jim Power on December 24, 2014, 3:12 pm, in reply to "Re: VW Golf tdi " Edited by board administrator December 31, 2014, 10:46 am
I'l call this a fix although not so sure. I fitted a new electric in tank pump. I tested the pump in a container before fitting and it made 1.6 bar dead headed.
I fitted the pump and now have 1.1 bar on the supply circuit and 11.5 bar at 4000rpm at the tandem which is correct I believe.
The car now starts fine, which was the original problem but I still think there is too much pressure on the supply circuit. I would rather see a value of around 0.70 bar or even less
Angus, thanks for the offer of docs and Joe, also thanks to Christy Doyle for the call and best wishes to everyone for Christmas and new year.