Club Touareg Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Filled up with gas last week and about 10 seconds after driving away the car died. This continued as I limped it home. Messed around with it all afternoon and couldn't figure anything specific out but my hunch was something to do with the computer or sensors because it continued to start fine and then after the 10-15 seconds run rough and like it was starving for gas before usually dying at some point. Sometimes it would roar back a bit and idle normal for 5-10 seconds again before going rough or dying.
The next morning it would ONLY run the 10-15 seconds and then die. Had it towed to a mechanic who just got back to me and said he traced the issue to the relay fuel pump, however when he pulled the pump and bench tested it it seemed to work fine. He also told me that if he jumps the relay the car will run fine. (He replaced the relay and that did not fix the issue. Now he is telling me he doesn't think he can help (because he thinks it's computer related and the relay just isn't getting a signal from the computer) and that I'll need to go to a dealer. Any ideas? ECU? I'm lost.
 

·
Registered
Joined
·
3,344 Posts
Welcome to the machine. Lots of fuel pump cases over here so you will not be alone. You will need some reading and we will need more details about how the treg was doing prior to this.
By the way that’s a know issue.
Different cases and solutions.
Here is one.




Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
I've been digging around and will continue to. This is my girlfriends car and she has had it about 3 years. Only known mechanical issue was the fuel pumps failing. Both fuel pumps were replaced in January 2019.

Was running fine prior to this issue. Code P0420 was getting thrown for the past several months but that is pretty unrelated imo.

Since the mechanic isolated this to the relay but has no other answers I'm just not sure what else besides the computer it could be.
 

·
Registered
Joined
·
3,344 Posts
Some issues were related how the pumps were put back and what damage had the mechanic caused either to the hoses or the seals. Stuff must be fitted correctly there or pressure is not maintained.

Get this kit


And test the pumps using the pdf files I posted in my fuel pump thread. You have to troubleshoot. No guessing allowed. Once you make sure the pumps are pushing the right amount of fuel indicated in the pdf files you can move forward. Your issue means the primary pump on the passenger side is not working. The priming pump starts the engine and the primary pump takes over. Test the pumps separately then the fuel hoses then we can talk about the ecu.


Sent from my iPhone using Tapatalk
 

·
Registered
2005 Touareg - 3.2L BMX
Joined
·
600 Posts
Sounds like passenger side pump is bad or the transfer lines from the drivers side pump is/was not properly connected. All the hose connections are push pull to release. Can not become disconnected easily by self. It is possible to not properly connect and can work loose even under the low pressure of the pump system . When I replaced my pumps I did not properly seat one of the lines and after priming engine would die. Check the lines to the passenger pump . Will have to open both sides. Although the pump runs the car once priming is done it is not really the primary pump. The primary side of the odd shape fuel tank is on the drivers side. It holds much more fuel than the secondary side of tank which is on passenger side . The pump behind the driver not only primes the system at start up it also transfers filtered fuel from the larger side of tank ( primary) to smaller side (secondary) tank replenishing the fuel to that side of the tank as needed by the pump activity. Just because a pump works doesn’t mean it is good. I can hook up a radio control car battery to a pump in situ and get it to work, doesn’t mean flow rate is adequate or pressure. When I did my pumps I replaced both pumps the filter flange assembly and pressure regulator flange assembly (passenger side) and gaskets. Other than screwing up on a connection has been fine for years. Sometimes the suction pumps just don’t pull enough fuel even though pump may work. Never hurts to make sure power is going to the 4 pin connector that goes to the flange assemblies.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
Thank you for the detailed input. Where I am at now is that it really does seem isolated to a signal getting to the relay to control the pumps. with a jumper wire in the relay making the pumps "always on" the car runs and drives like normal. Pull the wire and replace with a brand new relay and the car returns to running for 10-15 seconds an dying. I can't see how this is a pump or flow issue if it runs and drives fine with the pumps jumped to always run...seems to me like the VW mechanic was correct in that it is an issue of a signal getting to the relay and telling the pump(s) to run. But maybe I am missing something?
 

·
Registered
2005 Touareg - 3.2L BMX
Joined
·
600 Posts
Well, when you open the drivers door a signal is sent to the entry authorization control unit. A signal is also sent from the drivers door control unit and on board power supply control unit which actuate the relay to prime the pump. Priming will continue until ignition is turned on. One of the control units must not be sending signal my best guess.
 

·
Registered
2005 Touareg - 3.2L BMX
Joined
·
600 Posts
I have two relays for the fuel pumps one is square the other a 404 rectangular. Can’t recall which is for which pump or what activates the passenger side pump relay. Think the 404 is for passenger side pump. My bet the missing signal is still tied to the entry and start authorization control unit or perhaps anti theft or perhaps ignition switch. Something has to fire signal the so pump is energized. Perhaps the ecu, but don’t think so.
 

·
Registered
2005 Touareg - 3.2L BMX
Joined
·
600 Posts
Ok, found one of my notes that slot C19 in the e-box is fuel pump relay J17 (404 type) priming pump ( closet to fuses) and slot A6 is fuel pump 2 relay J49 passenger pump. So you have to figure out why J49 relay is not being actuated. Perhaps a stupid question. Did you check the fuel pump fuses in the e-box? Position S13 (15A) is pump 2 and position S14 is pump 1. Would also check position S10 as fuel tank leak diagnosis is on that fuse along with radiator fan control unit, brake servo relay and AC high pressure sender.
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top