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Discussion Starter #1 (Edited)
First I want to say this site is great and I've learned a lot by skimming through the threads over the years, so thank you everyone. I just joined as a member because it seems like I just can't figure out this problem and really need some of your help, please!

I've had my treg for a few years now, bought it used with rather low miles. I have the 2004 V6. I am at about 90K now, we've had our problems but I really like it and I want to get the problems taken care of so I can continue to enjoy driving this fine vehicle.

A bit of history: Within the first week of owning it, there was a major transmission issue, I don't know what the outcome or fix ended up being because the dealer covered it (we didn't buy the warranty but it happened just days after driving it off the VW lot). I was driving and it quit shifting and then would no longer go forward. They towed it and it was a transmission problem is all I was told.
It was fine after that for a while then maybe about a year later the fuel pump quit, around 60K miles. That is when I first became familiar with the forum and discovered right away that it was my main fuel pump, I had the 30 second dying problem. We have a mechanic on staff (small business, works on the company vans and trucks, all domestics, no VW's or complicated foreign vehicles), gave him all the info and diagrams for replacing the pumps, he did both as I read it was a good idea to do, problem solved and I was up and running again no problems.
Then somewhere between 6 months to a year later, a whining/squealing noise started coming from the pump when the fuel level is getting close to 1/4 tank according to the gauge. It runs rough sometimes, doesn't shift properly sometimes, is sluggish sometimes when you press the accelerator, and when in park and idling, the rpm's will go up and down like you are revving the engine with the pedal but its doing it on its own.
I feel that I may have multiple issues going on and I'm trying to sort them out. From what I can tell the issues all seem to revolve around a low fuel level (less than half, getting closer to 1/4).
So our mechanic started with replacing the fuel filter as that sounded like a starting point from what I read and that it may not be the pumps. That really didn't make the problem any better, but while he was in there, which he was going to replace both pumps again but we decided to hold off and start with the filter as it does appear that both pumps are functioning and the problem is definitely different from before, but he noticed that the main pump side was without fuel, while the other pump (starting pump), was full. Should they be level and what would be the reason for them to not be level? That makes sense to me why it is whining if there is no fuel or very little to be pumped, but how do we fix that? And that makes sense for it to run rough if it isn't pumping the fuel like it should be. As far as the idling problem, I though that may be the PCM, I read about those having a hole?? and causing issues with the idle.
So of course my solution right now, is just to not let the fuel level go below 1/2 tank and that gets me everywhere I need to go, but I would like to fix these problems for the health and life of my Touareg.

Any help would be much appreciated, thank you!
 

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First I want to say this site is great and I've learned a lot by skimming through the threads over the years, so thank you everyone. I just joined as a member because it seems like I just can't figure out this problem and really need some of your help, please!

I've had my treg for a few years now, bought it used with rather low miles. I have the 2004 V6. I am at about 90K now, we've had our problems but I really like it and I want to get the problems taken care of so I can continue to enjoy driving this fine vehicle.

A bit of history: Within the first week of owning it, there was a major transmission issue, I don't know what the outcome or fix ended up being because the dealer covered it (we didn't buy the warranty but it happened just days after driving it off the VW lot). I was driving and it quit shifting and then would no longer go forward. They towed it and it was a transmission problem is all I was told.
It was fine after that for a while then maybe about a year later the fuel pump quit, around 60K miles. That is when I first became familiar with the forum and discovered right away that it was my main fuel pump, I had the 30 second dying problem. We have a mechanic on staff (small business, works on the company vans and trucks, all domestics, no VW's or complicated foreign vehicles), gave him all the info and diagrams for replacing the pumps, he did both as I read it was a good idea to do, problem solved and I was up and running again no problems.
Then somewhere between 6 months to a year later, a whining/squealing noise started coming from the pump when the fuel level is getting close to 1/4 tank according to the gauge. It runs rough sometimes, doesn't shift properly sometimes, is sluggish sometimes when you press the accelerator, and when in park and idling, the rpm's will go up and down like you are revving the engine with the pedal but its doing it on its own.
I feel that I may have multiple issues going on and I'm trying to sort them out. From what I can tell the issues all seem to revolve around a low fuel level (less than half, getting closer to 1/4).
So our mechanic started with replacing the fuel filter as that sounded like a starting point from what I read and that it may not be the pumps. That really didn't make the problem any better, but while he was in there, which he was going to replace both pumps again but we decided to hold off and start with the filter as it does appear that both pumps are functioning and the problem is definitely different from before, but he noticed that the main pump side was without fuel, while the other pump (starting pump), was full. Should they be level and what would be the reason for them to not be level? That makes sense to me why it is whining if there is no fuel or very little to be pumped, but how do we fix that? And that makes sense for it to run rough if it isn't pumping the fuel like it should be. As far as the idling problem, I though that may be the PCM, I read about those having a hole?? and causing issues with the idle.
So of course my solution right now, is just to not let the fuel level go below 1/2 tank and that gets me everywhere I need to go, but I would like to fix these problems for the health and life of my Touareg.

Any help would be much appreciated, thank you!
My bet is the pressure regular flange above the fuel pump behind passenger seat is bad. A line from the priming pump runs to the other side and connects to the pressure regulator. There should always be fuel in the tank behind the passenger seat. The priming pump is also a transfer pump and moves fuel from the larger side of the tank (primary) to smaller side as needed. If there are problems with the pressure regulator could cause issue of no fuel in the secondary side of fuel tank.

On the other item buy a new Pollution control valve (PCV). Black saucer shape on top of the intake near the throttle body on passenger side with hose connecting to cyclone separator on back of block.
 

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Discussion Starter #3
Thank you for the info, we ordered the regulator yesterday and I'll update this once we've replaced that.
 

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Thank you for the info, we ordered the regulator yesterday and I'll update this once we've replaced that.
If the regulator did not work verify that your filter assembly is not leaking. If the filter assembly is leaking the lose of pressure can stop fuel flow to the other side.
 

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If the regulator did not work verify that your filter assembly is not leaking. If the filter assembly is leaking the lose of pressure can stop fuel flow to the other side.
actually a leak in fuel filter assembly will cause pumps to not get power. a safety feature. my first step before buying all kinds of **** you dont need would be to first, check the pressure of pumps, then check for 15 second volume test on each pump individually. 15 sec. will yield approx. 800mL of gas. if pump does not produce this amount then pump motor is loosing life and needs replaced.


TBH i would have started with checking the quality of fuel filter and replace if needed.
 

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actually a leak in fuel filter assembly will cause pumps to not get power. a safety feature. my first step before buying all kinds of **** you dont need would be to first, check the pressure of pumps, then check for 15 second volume test on each pump individually. 15 sec. will yield approx. 800mL of gas. if pump does not produce this amount then pump motor is loosing life and needs replaced.

TBH i would have started with checking the quality of fuel filter and replace if needed.
Think replacing the filter is one of the first thing they did. Main problem was gas not flowing to other side of tank.

Not aware of a sensor that detects fuel leaking from either of the flanges that kills power to the pumps. Is it pArt of the flange? Know there is a crash sensor that does so.

A lot of money is spent with fuel pump issues and a great way to test the pumps is flow as you indicated. Not certain if that will determine a flow issue between sides?
 

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Discussion Starter #8
Hello, thank you for all your help with my problems! So I just picked my treg up yesterday (we were in Florida so our mechanic took his time working on it) and its running much better--starts right away, no shifting issue, etc but I'm also not yet to my problem point with the fuel...1/4 tank. So I'll update this again later this week so I can see how it does when it gets to where the issues really start! But for now it does seem to be running great and I no longer have all of my sensors beeping and flashing at me!
So far we have done the following:
-Replaced the fuel filter (because we did not do that when I originally had the pumps replaced 2 years ago??) We started with that being the "simple fix" before moving on to the more complicated items.
-Changed the spark plugs
-Replaced the Pressure Regulator Flange (as described above by G6mdxvct)
-Replaced the Intake Manifold Actuator Left Side (Drivers) According to the codes, I had a vacuum leak and that is the park VW dealer prescribed :)

So thank you for the help and I'll let you know soon!
 
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