# fuel filter location



## chipmjohnson (Sep 11, 2007)

Where exactly is the fuel filter. I have been random hesititaitons expecially when less than a full tank of gas. Plugs didnt make a difference and the dealer couldnt reproduce. So I thought I would change the filter and take that one off the list if nothing improves.

Thanks


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## PanEuropean (Nov 3, 2001)

Chip:

What engine do you have in your car?

Michael


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## chipmjohnson (Sep 11, 2007)

*Fuel Filter 4.2V8*

I have the V8.


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## Jxander (Aug 5, 2008)

Chip:

I too would like to change my fuel filter as a preventative measure. No discussion of it since it is not part of any scheduled maintenance, so no one seems to change it. I am certain that it is near the fuel tank but cannot ascertain from the Bentley manual whether it is accessible without removing the fuel tank. if you have to remove the tank it will be a nightmare of a job, requiring dropping the exhaust and more. However, I suspect it is more accessible than that. I'd recommend crawling up underneath it and look around the fuel tank area. One of these days I'm going to do the same.

Possibly someone will have already done this and knows exactly where the fuel filter is located.

Jim X


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## PanEuropean (Nov 3, 2001)

I looked in the repair manual and could not find a specific procedure for changing the fuel filter. There is a diagram in the repair manual that shows the fuel filter located at the lower, forward end of the fuel tank. It appears that it is accessible from below the car without further disassembly.


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## 611 (Sep 1, 2010)

WoW thats one complex looking fuel tank. Now thats the only fuel tank diagram I have ever seen, but it was always so much simpler in my head. I just always thought of a big tank with a pump at the lowest point. 

Also, I thought that reserve fuel was just a concept. For example when you had say 2.5 gallons left in the tank a light would come on. Is that not the case here? Is there really a separate little tank? And if so is that typical?

Kevin


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## Jxander (Aug 5, 2008)

Michael:

Thanks for the pic. As always, you're right there with the info. At least we now know the specific area to look. 

I'm still curious why they have no scheduled replacement cycle? i guess it may be because it depends on the cleanliness of the fuel used and that's not someting predictable by VW. If it is easily accessible, I'd still feel better replacing it every 50k-60k miles. Which means I am now 8k miles overdue. 

Jim X


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## PanEuropean (Nov 3, 2001)

611 said:


> ...Is there really a separate little tank?


Hi Kevin:

No, that thing up at the top left is not a separate tank, it is an expansion chamber for gasoline vapour. Volkswagen of America did a poor job when they translated the callouts on the illustration from the original German.

Below is a photo of an actual tank, cut away to show what is inside it.

Michael

Fuel Tank Cutaway (gasoline powered Phaeton)


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## Itzmann (Jan 16, 2006)

What an amazing, mind-blowing picture. Fuel transfer pumps? Like on an airplane? On a fricking car? *Give me a break*. Was there absolutely no way to communicate the bottoms of the tanks via a $1 tube as opposed to hundreds of € in parts plus $ in labor when either of these pumps, or their wiring, or their sensors, or their controllers fail?

I've seen overengineering on the Ph, but this takes the cake. 

Also, I agree with the feeling that the fuel filter *needs* to be changed, service manual notwithstanding. I was precisely thinking about that a few days ago. In particular, for decades fuel has been a lot cleaner in Europe than in the U.S. because of the distribution network, fuel tank standards, etc. Maybe in Deutschland they figure you can use the same filter for the "useful life of the vehicle" of 15 years, but this simply does not hold in the U.S.

I for one plan on requesting a fuel filter replacement on my next scheduled service in mid-year 2011. My car will have been in service 7 years and I'm betting the filter is already muddy. 




PanEuropean said:


>


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## PanEuropean (Nov 3, 2001)

Itzmann said:


> Fuel transfer pumps? Like on an airplane? On a fricking car? Was there absolutely no way to communicate the bottoms of the tanks via a $1 tube...


The problem with using a $1 tube on a car is the same as when a $1 tube is used on an aircraft - fuel will always move, by gravity, to the lowest tank.

This means that when the vehicle is parked, if it is not on a perfectly flat surface (consider that most roadways are crowned), fuel will migrate to the lower of the two tanks. Not good when the delivery outlet to the engine is in the 'other' tank.

Note that (like airplanes), the technology used to move the fuel from the left tank to the right tank is a jet pump (also known as a motive flow valve, or venturi). Such a pump has no moving parts, and uses excess output from the 'normal' fuel pump to transfer fuel. It is pretty simple and very well-proven technology.

Michael


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## Itzmann (Jan 16, 2006)

Amazing.

You know, at the Gläserne M, they showed us the station where they "put in the whole gas tank" in one step via the trunk. Big piece of plastic! My party was duly impressed.

We were bobos in paradise. I don't think we realized at the time that inside the plastic container there was a lot other than just gasoline...


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## PanEuropean (Nov 3, 2001)

Here's a better picture showing the fuel filter location:


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## Jxander (Aug 5, 2008)

> Here's a better picture showing the fuel filter location:


Wow - the Phaeton.. beautiful from any angle. 

I see now why the exhaust has to be dropped for numerous other repair jobs. It is tucked into the center tunnel with all the drivetrain stuff.

I've yet to climb under my Phaeton with 2.5 years of ownership. One of these days I will have to do it if only for the enjoyment of looking around. 

Jim X


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## Auzivision (Apr 19, 2007)

Wow, that is one amazing looking gas tank. I had no idea how complicated it was, just always wished it were bigger. Looks like they pretty much maximized the available space. 

If anyone changes their fuel filter, it would be nice if they dissect the old one a report back pictures. Looks like it wouldn’t be too difficult to change, but at the same time is it necessary or will it help. 

Fuel filters seem to be one of the items people gravitate toward changing, but I have yet to hear a story that it ever fixed a problem or improved anything. I’m beginning to think that changing fuel filters isn't as necessary as it used to be. With all the evaporative emission systems, dust and dirt has a tougher time entering the system.


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## PanEuropean (Nov 3, 2001)

Auzivision said:


> I’m beginning to think that changing fuel filters isn't as necessary as it used to be. With all the evaporative emission systems, dust and dirt has a tougher time entering the system.


I agree with you. VW is pretty conservative with their service schedules - if they did not put in a replacement interval for the fuel filter (and it appears that they did not), then I think they are pretty confident that it does not need to be replaced unless some exceptional circumstance (e.g. contamination of the fuel tank) arises.

Michael


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## chipmjohnson (Sep 11, 2007)

*filter location*

Thanks for the info and great pictures. I picked up a new filter and the replacement is on the schedule for this weekend. I hope it helps with the problem. Either way, its due for a dealer visit anyway, as my TPMS has developed a mind of its own since the summer.


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## PanEuropean (Nov 3, 2001)

Hi Chip:

I would be really grateful if you would write up a little "how-to" explaining what is involved in replacing the filter - as you know, the Repair Manual doesn't address this issue.

If you wish, you can send photos to me by email and I will then host the photos for you, allowing you to embed them in your post.

Regards,

Michael


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## Motorista (Oct 28, 2005)

PanEuropean said:


> Note that (like airplanes), the technology used to move the fuel from the left tank to the right tank is a jet pump (also known as a motive flow valve, or venturi). Such a pump has no moving parts, and uses excess output from the 'normal' fuel pump to transfer fuel. It is pretty simple and very well-proven technology.
> 
> Michael


And a fairly common one: Subaru, for example, has been using a similar saddle-shaped tank and fuel compensating technology in the Outback for 10-15 years, with excellent reliability. 
Regarding fuelf filter replacement the location seems fairly accessible but I wonder if there is a procedure for depressurizing the circuit before replacement: some cars have it, others do not. By the way, a fuel filter is not simply filtering dirt but also separating water (condensation, etc.) and preventing it from entering the intake. So I'd be leaning towards an eventual replacement.
Stefano


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## Cortexiphan (Mar 2, 2010)

I don't know if the fuel filter is anything like the one's on the .:R32's

But be very careful with the clips on the ends of the fuel filter.

I remember reading a story about a guy who broke the clip on the fuel filter, ended up costing him over $2000 for a shop to drop the tank and replace the line.

IIRC the clip looks like it pulls out, but actually pushes in.

Good Luck, hope it fixes your problem 

-Tim


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## PanEuropean (Nov 3, 2001)

Hi Tim:

Thanks very much for sharing your wisdom about the fuel filter clips, that is very thoughtful of you.

By the way - welcome to our forum!

Michael


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## Cortexiphan (Mar 2, 2010)

PanEuropean said:


> Hi Tim:
> 
> Thanks very much for sharing your wisdom about the fuel filter clips, that is very thoughtful of you.
> 
> ...


Thank you very much.

I remember someone asking about pictures of what a used fuel filter looks like.

When searching the MkIV forum for examples of the clip I was talking about I ran across these pictures: source






I know its not from a phaeton and I don't know how many miles were on the car. But its a good example.

-Tim


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## ReallyOldGuy (Jul 22, 2010)

After those photos my guess is VW is going to have a rush on Phaeton fuel filters.......yikes!


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## PanEuropean (Nov 3, 2001)

Er, I don't know about that - I kind of subscribe to the "If it's not broke, don't fix it" school of thought. In other words, unless you have a reason to suspect that the fuel filter has been contaminated, I would leave it alone. It is a pretty big object and can cope with a great deal of debris.

Michael


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## chipmjohnson (Sep 11, 2007)

*fuel filter replacement done*

Well I was able to get the fuel filter replaced yesterday. Like most things on the Phaeton, a few things to move out of the way first, but other than that it was a easy, straight forward job. Took me about 30 min start to finish. I'll try and post instructions and pictures later.

I did decide to cut open the filter after seeing the other picture. It looked very similar to that one but keep in mind that some of what you see are the metal shavings from the cutting of the case.

I dont think it solved my problem nor did I expect it to but one more thing I can cross off the list so when it makes it back to the dealer I save myself some time and money for them to "Try this first" answer.

Overall its designed to be a quick and easy replacement, so I would recomend chaning it about the 60k point. Not sure why its not on the schedule but if they didnt expect it to be replaced, they wouldn't have put quick push in connectors on both sides of the fuel line. 

Just my 2 cents worth.

Chip


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## Itzmann (Jan 16, 2006)

chipmjohnson said:


> I did decide to cut open the filter after seeing the other picture. It looked very similar to that one



This reaffirms my idea to have the filter replaced at the next maintenance.

Shavings or no shavings, the thing looks used up.


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## Cortexiphan (Mar 2, 2010)

I wasn't going to change mine until I ran across those pictures. My car only has 39,XXX miles on it. 

But when I hit 40,000 and I'll be servicing the AWD system and I might as well service everything.

I like preventative maintenance and decided a fuel filter is going on my list of things to replace.

Chip:

Have you tried replacing the coil-pack(s)? I know they are prone to die on other VW's not entirely sure if this is a common issue for the Phaeton but its worth a shot if you haven't ruled it out already.

-Tim


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## Auzivision (Apr 19, 2007)

These very compelling photos change my thinking about fuel filter not working that hard, but then again it's difficult saying what effects this much dirt/debris has on fuel pressure and flow. I guess so long as the pressure is correct and the pump isn’t overworking, leave well enough alone. Then again, if it’s not a difficult job, it might be worth doing. 

I’d be interested to hear how much work is really involved and what risks of complications may exist. The one and only time I changed a vehicles fuel filter I learned the hard way that you need to bleed down the pressure first… luckily nothing major happen, but the potential existed. After that is when I started hearing stories how changing fuel filters make people feel good, but don’t usually ever solve a problem.


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## Itzmann (Jan 16, 2006)

One thing to remember is that ethanol is hydrophilic, i.e., attracts and blends into water.

Since Phaeton was designed for good old petroleum, the stuff going into our tanks, filters and engines is very nasty compared to what the car was designed for (thank a corn-belt state lobbyist for this nonsense).

This sounds as good a rationale, to me, as any other as to why the manufacturer may have presumed the filter was good for the useful life of the vehicle, whereas in reality we may wish to be changing it every couple of years.


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## Jxander (Aug 5, 2008)

Itzmann said:


> .......This sounds as good a rationale, to me, as any other as to why the manufacturer may have presumed the filter was good for the useful life of the vehicle, whereas in reality we may wish to be changing it every couple of years.


Auto manufacturers compete with each other in many ways. One of the ways to compete is with lower maintenance expenses. So if a fuel filter "failure" is not common or generally would not occur until the car was beyond the manufacturer's moral responsibility(10 years or 100k ??) they're not likely to put it on the scheduled maintenance list. I do think manufacturers design their products to last well, but doubt they are very concerned about their vehicles and problems beyond about 10 years and 100k. However, it also seems to me that replacement would be cheap insurance, especially for those keeping their Phaetons for the long haul. If I knew I would only keep my Phaeton for less than 10 years and under 100k, I probably wouldn't consider changing mine either. However, a clear filter should minimally result in lower back pressure on that expensive fuel pump and I certainly don't want to get stranded because of "plugging" $20 part that is not too difficult to replace.

Jim X


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