2006 BRM Wouldn't start.. bad tandem pump

Hi All:
Thought I'd let the TDI family know that the tandem pump on my 2006 BRM with 96K miles died. It warned us somewhat, but I thought it was a weak battery causing the issue and not the pump.
More information for those who run across the thread...
Car: 2006 Jetta TDI (BRM engine with 96K miles)
Problem: Car wouldn't start. It would turn over fine, but simply wouldn't start and run.
Symptoms: Prior to the complete start failure, sometimes the car wouldn't start right away after making several trips around the city. Usually waiting a couple of minutes between cranking would get it to fire. When started, car would act fine.
Checked: ASV- OK. Lift Pump- OK. Tandem return hose- erratic flow.
Actions: Replaced fuel filter and J329 relay. Didn't help.
Solution: Replace tandem pump. No problems after replacement.
Extra info: According to the mechanic, the tandem pump was bad and allowing air into the fuel system and causing "loss of prime". He was eventually able to get it to start by allowing it to turn over for 30 secs. My battery was weak, so I was unable to do that in my driveway during my testing.
IMHO, If you have a BRM that is starting to "get hard to start" after many trips around town, or when you first start in the morning, that may be a sign that your tandem pump is going out if your lift pump is ok and your ASV is ok.
Hope this helps someone.
-Ed

What is a lift pump and ASV?

ASV=anti shudder valve and I think the lift pump is in the fuel tank on the PD's

https://www.google.com/search?q=tdi...la:en-US:official&client=firefox-a&channel=sb

https://www.google.com/search?q=tdi...g.mozilla:en-US:official&channel=sb&q=tdi+ASV

That does help and thank you for posting your problem and then the solution, that stuff is very helpful.

Thanks, how long should it take to replace a tandem pump? A shop told it would cost $250 in labor plus $450 for the part. I have heard it should only take not more than 1 hr. It looks easy DIY.

Some here have successfully installed a one-way valve (with a predetermined "pop" pressure) between the fuel filter outlet and the tandem pump to prevent the loss of prime. But I'm glad you got it narrowed down and fixed without spending too much money.

Yes, it's nice to see a thread with some real info in it. The pump should only take an hour or maybe two to change depending on your abilities. They don't cost $450.

I think I'm having the same problem, how do you test the tandem pump? Vacuum or pressure test it? I was reading that it should have around 50psi, is that right?

I posted on this forum already, you can read about it. I did open up the tandem pump but it looked normal to me. I understand there is a rebuild kit for about $70. I'm just not entirely sure that it's my problem also. The computer codes give a warning for the injectors.

https://forums.tdiclub.com/showthread.php?t=397112

Been having the same issue.... hard starts after a long time sitting. Replaced tandem 2 days ago and still having hard starts. How can you test the ASV or lift pump? I do have a VCDS.

mikeb95 said:

Been having the same issue.... hard starts after a long time sitting. Replaced tandem 2 days ago and still having hard starts. How can you test the ASV or lift pump? I do have a VCDS.

Click to expand...

You should be able to hear the lift pump in the tank cycle for a few seconds after you turn on the key.


I just ordered a new tandem pump myself, I have been having excessive crank times off and on, sometimes I can go weeks or a month and then it will take a lot of cranking the engine over to get it to start. If I put the accelerator pedal to the floor it seems to start quicker, which to me seems like a fuel issue more then a electrical issue with some sensor.