VW Jetta TDI Tandem Pump, Problems Starting

lsamuels

New member
Joined
Oct 19, 2012
Location
Toronto
TDI
Jetta
Hi Everyone,

I would like to know if the Tandem Pump (Jetta TDI 2006), can it be rebuilt or repaired? I am having Starting Problem. I intalled a check valve but it hasn't rectified the problem.

Does anyone have any suggestions?
 

pruzink

Veteran Member
Joined
Sep 25, 2004
Location
Granbury, Texas
TDI
GLS, 2004, silver
I wouldn't be to quick to condemn your tandem pump. There are a # of things that can cause extra cranking to start. There are a couple of relatively easy things that you can do to get an idea if the tandem pump is pumping. One is to get a can of diesel purge & observe the PD rail return flow going back into the can of diesel purge. The tandem pump also has a port to install a gauge to look at the pump discharge pressure. One time I had a bad coolant temperature sensor that gave me extended cranking on starting. One other time I made an adjustment on my timing (setting torsion value) trying to advance same to improve fuel economy & once I set it near reccomended, my car was terrible starting so I had to set it back. There are other things like the camshaft position sensor that are there to make the car start better that can cause long cranks. Have you used Vagcom to see if you have any codes?
 

lsamuels

New member
Joined
Oct 19, 2012
Location
Toronto
TDI
Jetta
I wouldn't be to quick to condemn your tandem pump. There are a # of things that can cause extra cranking to start. There are a couple of relatively easy things that you can do to get an idea if the tandem pump is pumping. One is to get a can of diesel purge & observe the PD rail return flow going back into the can of diesel purge. The tandem pump also has a port to install a gauge to look at the pump discharge pressure. One time I had a bad coolant temperature sensor that gave me extended cranking on starting. One other time I made an adjustment on my timing (setting torsion value) trying to advance same to improve fuel economy & once I set it near reccomended, my car was terrible starting so I had to set it back. There are other things like the camshaft position sensor that are there to make the car start better that can cause long cranks. Have you used Vagcom to see if you have any codes?
I noticed when I park the car, when the back is higher then the front, the car starts. When I park the front higher then the back, it starts and then immediately shuts off. I have to try and crank it for along time before it starts.
Please explain where the Camshart Position Sensor is located? Also I googled "Vagcom" as I've never heard of it. I will check it out but I don't know anything about that site and "codes" to look for. If I have any questions pertaining to the site if I run into problems, I will post my questions here.

Much appreciate the help.
 

pruzink

Veteran Member
Joined
Sep 25, 2004
Location
Granbury, Texas
TDI
GLS, 2004, silver
I have seen more posts in here for the Lift Pump in the fuel tank failing than for the tandem pump failing. Doing a "diesel purge" procedure allows you to get a look at what both pumps are doing. The fuel line from the lift pump going to the fuel filter gets jumpered to the thermostatic tee return from the fuel filter going back to the fuel tank. The line that feeds the fuel from the fuel filter to the tandem pump sits in the diesel purge as the fuel supply until the can is emptied & the fuel injector rail return goes into the can of diesel purge also (this will show you how much fuel the tandem pump is pumping). The camshaft position sensor is under the upper timing belt cover & there is a metal plate behind the camshaft drive gear that it looks at to determine which cylinder is going into compression (this makes for easier starts). There is also a write-up in here with some grounding issues with this sensor & the fix to correct this grounding problem. If the uphill/downhill orientation of the car making for an easy or hard start is consistent I would agree that it sounds like a lack of fuel issue. There are writeups in here about the lift pump (some models will not allow fuel to flow through the pump if it fails but others will; dang44 has some very detailed writeups on this pump).
 

TrialandError

New member
Joined
Oct 16, 2013
Location
Cincinnati
TDI
2006 VW TDI
Uphill/Downhill

Isamuels, did you ever resolve your starting problem with the car facing uphill. I have the same issue after a new tandem pump was instralled. I think air is getting trapped in the line somewhere/somehow. (5/20/14)
 

Sjstal

Member
Joined
Jul 9, 2014
Location
Wild & Wonderful WV
TDI
99/04 1.9L jetta
I wouldn't be to quick to condemn your tandem pump. There are a # of things that can cause extra cranking to start. There are a couple of relatively easy things that you can do to get an idea if the tandem pump is pumping. One is to get a can of diesel purge & observe the PD rail return flow going back into the can of diesel purge. The tandem pump also has a port to install a gauge to look at the pump discharge pressure. One time I had a bad coolant temperature sensor that gave me extended cranking on starting. One other time I made an adjustment on my timing (setting torsion value) trying to advance same to improve fuel economy & once I set it near reccomended, my car was terrible starting so I had to set it back. There are other things like the camshaft position sensor that are there to make the car start better that can cause long cranks. Have you used Vagcom to see if you have any codes?

I'm having a similar problem with my coolant temp sensor causing extra crank while starting. Can you replace that sensor, if so, how?
 

Dadwagon

Well-known member
Joined
May 20, 2018
Location
Canton, ct
TDI
2004 Jetta Wagon
Any solutions ever found for this?

Hi Everyone,
I would like to know if the Tandem Pump (Jetta TDI 2006), can it be rebuilt or repaired? I am having Starting Problem. I intalled a check valve but it hasn't rectified the problem.
Does anyone have any suggestions?

Hey all,
I am having this exact issue, and i don’t see that any solution was ever discussed or posted, anyone have an idea what may causes hard cold starts on the pd engine when parked uphill?
 

Page

New member
Joined
Jan 11, 2022
Location
Cape Town
TDI
1.4 TDI
I noticed when I park the car, when the back is higher then the front, the car starts. When I park the front higher then the back, it starts and then immediately shuts off. I have to try and crank it for along time before it starts.
Please explain where the Camshart Position Sensor is located? Also I googled "Vagcom" as I've never heard of it. I will check it out but I don't know anything about that site and "codes" to look for. If I have any questions pertaining to the site if I run into problems, I will post my questions here.

Much appreciate the help.
Was this problem solved and what was the cause?
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Was this problem solved and what was the cause?
The last time the Original Poster visited the TDI Club was on May 13, 2013 ... slightly over one month after starting this Thread.
 
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