Fuel Filter "Hum" Normal or No?

[Tusin]

I replaced my fuel filter about two weeks ago. Car seems to run fine.... But the other day I notice a very very low/queit hum while sitting at a light with my music off (very rare lol). Today I try to find the source, it is indeed coming from my fuel filter....

I am going to assume it is not normal, as it seems I would have noticed it with my original filter at some point in time. The ONLY thing I can think of, is it is not an OEM filter it is a Mann filter. I have used Mann filters (oil and such) in the past with no issues at all. So before I go to the stealer and drop $45 on a OEM filter, just want to make sure that this is not considered "normal".

[Dangler]

i changed my fuel filter the other day, but haven't noticed a hum....mine is also a Mann fuel filter. If anything changes, i'll be sure to let you know.

[00s4slvr]

usually when the fuel filter is humming it means it needs to be changed, however in this case i have no idea since you just changed it...

[Matt@EuropaParts]

Mann is an OE supplier to Audi, so it's weird that you're having that noise (you shouldn't). Is it installed correctly?

[Dangler]

also, for you guys that have changed your filter, did you have trouble getting the fittings off the old filter. I had the schwaben tool to remove the line, and I had an ordeal on one of the fittings, that i had to cut the nipple off the filter and then use pliers to pull the nipple out of the line. a change that should've taken minutes took 30 minutes fighting with a fuel line.

[Sal_B7]

^^wow really? I just used a flat head to pop off those lines. Not sure why they say you need a specific tool.

Tusin- did you make sure that the arrows were going the right way? Thats the only thing i can think of as far as installation goes. hmmm...

[Tusin]

I think it would be dang near impossible to install it incorrectly. Maybe I just got a bad filter. I think I may pick a new one up, and double check my install on the old one before putting a new one in.

I will take a video/audio recording and post it on youtube here in a minute.

[Sal_B7]

There you go. Yeah you are right. It is kinda hard to do it wrong. Just checking though.

Hook us up with a link when your done.

[Tusin]

Tried to take a video, but didn't work out to well. To much ambient noise right now.

[ECS Tuning-Audi]

You are certain it isn't your fuel pump, not your filter? As stated above - these Mann Filters (http://www.ecstuning.com/Audi-B7_A4-Quattro-2.0T/Search/Fuel_Filter/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply) shouldn't have any issues. Before you buy a replacement, remove - drain - reinstall your filter and see if you still have the humming. It may be a clip fitting isn't all the way pressed on so the pressure is causing that "humming." Certainly don't goto a dealer for a new filter - if you find fault with your present one we have Mann filters for 32.63 from that link.

[Tusin]

I guess it could be my LPFP.... Isn't there some log I can do with a Vag-Com to test the LPFP?

[dengi]

I have the same exact problem.
Had LOUD humming noise, went to a local euro shop and paid $95 for new filter + service. Humming went away for 2 days, and it just came back again, but it sounds a little bit different...still humming though...the sound is the most irritating sound I have ever heard...does anyone have a solution?

[gyroscope]

When my car was humming it was the rear fuel pump. Replaced under warranty, after it left me stranded.

[vannyhuj]

I replaced my filter with Mann about 1k miles ago, no issues. I assume the connections are good, otherwise you'd be streaming fuel. It probably is a pump, but it you have the old one I guess you could put it back on and see if there is any difference. I also did not have any special tools for this, definitely not required.

[Tusin]

Any other symptoms with the bad fuel pump (assuming LPFP)? Or just the noise?

I have no codes at all. I could have sworn I read that there is some log I could do with my vag-com to see if the LPFP is performing properly.

[illegitimus]

I replaced my fuel filter about 500 miles ago and no humming. I am inclined to think it might be your LPFP. on that note, did I hear it correctly that one needs to drop the fuel tank to do it or it can be replaced by pulling the rear seat bench?

[vannyhuj]

Any other symptoms with the bad fuel pump (assuming LPFP)? Or just the noise?

I have no codes at all. I could have sworn I read that there is some log I could do with my vag-com to see if the LPFP is performing properly.

Try this:
1. Connect the vag-com
2. Turn the key to the ON position (don't start the car)
3. Select "OBD II", then "Mode 1: Read Data"
4. Select module "35 - Fuel Rail Pressure"
5. It should be relatively steady at 600 kPa

If it is not, then then there is a good chance the LPFP is not working correctly.

[Tusin]

Awesome thanks vanny. I actually brought my vag-com kit to work with me so I will check it.

And dengi, can you describe your humming a bit more? Do you just hear it at idle? Does it change at all with speed? etc....

[vannyhuj]

No problem, I just checked mine and it stayed steady at 600 kpa, with a jump every once in a while to 610. Good luck!

[dengi]

Awesome thanks vanny. I actually brought my vag-com kit to work with me so I will check it.

And dengi, can you describe your humming a bit more? Do you just hear it at idle? Does it change at all with speed? etc....

it doesn't really change at all with speed, same sound at all speeds. sometimes it will go away while i'm driving, and start back up at idle. its more random after i replaced the fuel filter

[Tusin]

Hey vanny. Are you sure that is the correct "test"? I just did and mine is in the 4000's.

[vannyhuj]

Hey vanny. Are you sure that is the correct "test"? I just did and mine is in the 4000's.

Yeah, with just the key on (engine not running), it should only be at 600 kPa. Elsawin stated the same. This should show what only the low pressure pump is providing. At idle it should be up in the 4,000 range with the HPFP in the equation.

[Tusin]

Hmmm interesting. I would think if there was an issue with the LPFP the number would be lower than 600, not higher.

Hmmm maybe the car needs to be cold? When I did the test, I did just go for a drive, and the number was dropping (not super fast, but still dropping) from 4000 ish k.

[vannyhuj]

Hmmm interesting. I would think if there was an issue with the LPFP the number would be lower than 600, not higher.

Hmmm maybe the car needs to be cold? When I did the test, I did just go for a drive, and the number was dropping (not super fast, but still dropping) from 4000 ish k.

Confirm you do NOT have the engine running for this test? The only way to really test that pump is to keep the engine off.

[Tusin]

Yes the engine was off.

[vannyhuj]

Wow, not sure what to make of it then. I don't know how the LPFP could make higher pressure than advertised. I'm not sure what software version of vag-com I'm running, I wonder if we have different versions and the units are different. Can you confirm the units displayed are "kPa"? If not, then we would have to look at a conversion table with what Elsawin states. The only other thing I could think of is if there were a crimped line or something clogged somewhere, I think that could cause higher fuel pressure. That might explain the hum if the pump were having to work harder and possibly cavitating. You might want to take off the filter again and inspect all the lines.

[Tusin]

Hey vanny. Thanks again. Just got back from Vegas, so taking today off then I will inspect tomorrow.

[JmacZX7r]

On all the cars ive owned this means the LPFP is going out. Do you run your car down to empty a lot? The pump uses the gas to cool the motor and if you run it below 1/4 tanks the gas gets hot faster and doesnt cool the pump very well, especially in hot weather. Or if your filter was clogged it will have to work harder to get the pressure up, this causes wear in the internals. Now that it can flow freely the extra wear will make it hum. Ive gone through 3 LPFP on different cars and soon you will have starting problems and then its time to replace it. I never let my fuel go below 1/4 tank anymore and havn't had a problem since on any of my cars. My 0.02. These have all been on american cars so maybe german is different. No hum yet on my audi tho.

[VMRWheels]

Usually a hum in the fuel system is associated with the fuel pump.

[Tusin]

Hmmm. But wouldn't you think it is odd, if my LPFP was going out, why would it start making the noise after I changed the fuel filter?