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Fuel filter replacement on 2010 Eos Komfort means car is now disabled?

514 Views 10 Replies 2 Participants Last post by  voxmagna
I changed the fuel filter on my 2010 Eos and now the car won't start. Pulled the plugs to confirm my suspicion and they are dry, there is no fuel getting to the engine. So then I read online about how the car, for some godforsaken reason, is unable to clear out the air in the line without a laptop and a VCDS procedure. Apparently the older VWs were capable of self priming with the ignition key (as are all other cars in the universe) but not my Eos's vintage.

Has anyone else experienced this? Pretty ridiculous for such a simple filter change to cause a total debilitation of the car.
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Has anyone else experienced this? Pretty ridiculous for such a simple filter change to cause a total debilitation of the car.
You disabled your car! Unfortunately you and many others don't read workshop procedures before carrying out workshop work. You fall into the trap as a DIYer of doing what you have always done on older cars and then get it wrong. V.W regard replacing parts like this as 'Workshop service operations' and they assume you have the same knowledge, experience, and tools to carry out the work:

Modern efficient EFI engines pass very small amounts of fuel through their fuel injectors. V.W High pressure fuel injection pumps are of two distinct types: Mechanical driven from the camshaft and electrical using the battery. When you replace a fuel filter even assuming you filled the filter can with fuel? There will be a lot of trapped air, particularly if fuel has run back from fuel lines. You can imagine getting that air through timed fuel injectors the size of pin holes using engine cranking is virtually impossible.

You need to know and follow the safe procedure used on your engine for bleeding the fuel system. It's not a common 'one fits all' procedure. I can use my own method without diagnostics which is not now regarded as safe workshop practice, but search Google. V.W will advise the safest method for their shops to use.

When an engine is fitted with an electric HP fuel pump, a diagnostics fuel system purge is an automatic procedure that opens all the fuel injectors and runs the fuel pump for about 30 seconds. Ultra safe with no high pressure fuel squirting about and starting fires! This is usually long enough for air to be forced out, but may need to be repeated if cranking doesn't start the car.
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Hmm... makes sense. That's good intel. Today being Monday I got in touch with the local VW mechanic (non-dealer, but trained by VW) who suggested he's never had a problem using the key to clear the lines, i.e. just running the starter several times. He said it sounded like maybe I don't have a fitting on all the way. I'm pretty sure all three of those fuel filter fittings clicked on nice and snug, but I will double check. The other thing is, the car actually RAN right after I replaced the filter... I forgot to mention that. I swapped the filter, turned the key, started instantly, and I verified no leaks at the filter fittings. It was the next time that I went to start it that I got nothing... I'm guessing the air finally reached the engine at that point, and the initial running of the engine was just using the last few drops in the fuel rail or something.

I'm also going to check the fuses related to fuel delivery.

I'll follow up with what I find out. Car has been sitting the driveway all weekend. If all this fails, probably loading it onto a tow truck and off to the shop.
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Search the internet for bleeding Efi engine fuel systems. There are other non-V.W approved ways which I wouldn't post here for beginners to start fires! Fittings would be more of a problem on the low pressure pump suction side. Further on you would see fuel spurting out! I run the TDi and air in fuel lines is something I'm always aware of. When you get trapped air under pressure with fuel either side it behaves like a spring under compression and no fuel will move through the pinhole injector opening for only a few milliseconds. That's what's good about the V.W diagnostics approach for HP electric fuel pumps.
This is so frustrating. There are numerous videos of ppl just quickly replacing the fuel filter on their 2.0 VW engine, with a 6.6 bar Mann filter, and no one mentions the line bleeding issue, either in the videos or the comments. Combine that with a VW mechanic telling me you should just be able to use the key to bleed it makes me think something else is messed up here. It certainly seems like everyone else on earth with a gasoline engine has had no issues whatsoever with an airlocked fuel system. Once in a great while, in some dark corners of VW forums, I can find a post of someone who appears to be in a similar situation, but there's no resolution about how the problem was fixed.

I checked the clips and the fuses, I reinstalled the old filter, reinstalled the new filter, everything looks fine, no leaks, etc. I checked voltage in the line going to the fuel pump.

I don't see any coherent method of manually bleeding the VW gasoline system on the internet, yet.

Looks like I am going to have to wait 1.5 wks for an appointment at the shop, I will post back with any solutions that came up from them, or if I happen to figure out anything in the meantime but I think I have just about given up. This all seems bizarre.
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Just for reference, here's a guy from 14 years ago in the same situation. No resolution posted.

And then here's a convo about jumping the fuel pump, but several people saying how the air should clear itself out.

Fuel Pump Jumper

I won't post the links to the many videos and whatnot of people saying, "I just did my fuel filter in 30 minutes, runs great". Lucky bastards.
Nothing you say or read mentions the V.W workshop method using diagnostics I told you about. They don't sound like V.W workshop technicians, more like old hands brought up on carb. and mechanical fuel pumps? Since your car ran o.k before you touched it, the only conclusion is the problem is something you brought on and nobody really knows everything you did? A post from 14 years ago isn't likely to refer to a modern Efi engine with an electric HP fuel pump. Be careful what you read and trust. You mention 'Jumpering a fuel pump'? Many V.W electromechanical devices are connected to transistor modules - Good luck trying that one if you take out a solid state switch device. HP fuel pumps and controllers are very expensive to replace.

When you think you can DIY service a modern engine, it's best to spend a few bucks on a workshop manual and read it first before you start. If you search the internet, posts don't necessarily refer to your specific engine, variant, or year.
Solved. I can understand why the person from 14 years ago didn't post a resolution as well.
Fuel and return line were switched. It was that simple. There is nothing tremendously complicated about fuel getting to the engine... there is a low pressure pump in the tank that sends fuel to the engine bay through a filter. There's a high pressure pump in the engine bay that then sends the fuel to the injectors.

Unfortunately, the send and return lines from the low pressure pump have exactly the same fittings. So it is possible to switch them accidentally. In which case no fuel will make it past the filter.

This means that, yes, in fact, as with the many many posts online, with a gasoline engine, the car is very much capable of clearing out any air in the lines. The low pressure fuel pump will fill a new (empty) fuel filter with just a few turns of the key.

This is a (normally) simple job. Three fuel lines on the filter, one screw on the filter bracket... that's it. No manual needed, no special priming procedure needed. Fortunately for me, no VW techs needed either.
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The car was fine until you did work on it, so there's always going to be uncertainty about what you did. Where more than one fuel line or hydraulic may need to be disconnected it's usual workshop practice to mark or label them before removing.
Bro... you are trolling. I've taken the time to put valuable information on here for other users, and you're just trolling with extraneous grief. I appreciate what input you have, but the delivery method is questionable.

I started this thread with full admission that I didn't know what had happened, then posted about the mistake I'd made, so that everyone can see and maybe it'll help someone.

If there are just two lines in front of you on one side of the filter, and you don't know which one is send and which one is return, and there's no indication of which one is send and return, nor of which port is send and return, and one is blue and one is black, the odds of anyone labelling them are ... well, you get my drift.
Some of us starting workshop level service work read the workshop manual first before doing anything and note diagrams, procedures and safety issues therein. Direction arrows are often marked on components showing flow direction and how fuel and hydraulic lines are connected. When V.W use colors, they are often referred to in the service procedure which you didn't read.

The valuable information for others is: 'Read the EOS workshop manual procedures first and you won't make the same mistake'. You explained your problem, but your approach will give similar problems unless you learn from V.W instructions and not what you think is best or others tell you on the internet. That's not 'Trolling' but helping others too understand how to do service work correctly and not work the same way.
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