Fuel pump noise on 1.9tdi

[badade 1.8t]

Hi

not sure if I'm right but when I switch ignition I can hear noise for about 2-3s like you flushed your toilet is this something to do with air in fuel pump???

[gav_j_crompton]

I have a 2004 1.9 tdi and it does the same thing, I always thought it was just the fuel system priming itself (thought this is only a guess). Never really worried about it.

[PeteK]

Mine does the same noise for approx 1-2 secs, this is normal.

[bv123]

Yippee! someone else with exactly the same problem I have been searching the internet for weeks now about this and finally!

Yes, I get the same noise from the intank fuel pump. I describe it as a squishing noise or squirting noise... but after reading your desciption "I can hear noise for about 2-3s like you flushed your toilet " , yes that describes it pretty accurately!

Anyway, lots of people say its normal, but here's (the short version of) my story - my original fuel pump was not making this noise. It died due to wear and tear (humming noise got louder over 2 months - bearings on there way out?) but replacement pump now although working apparantly perfectly, makes this squish, squirt or *cough* toilet flushing noise.

Really feel it shouldn't be making any noise like the original pump. Hope its just excess fuel the pump is squirting back into the tank. So maybe newer fuel pumps are a modified design?

Found this quote from elsewhere on the internet -
"Normal, fuel pump priming. Mine only does it when the fuel gauge has dropped to just above 1/2 full. "

[Peter D]

The pump always primes at power on 3 seconds ish, but it should just hum. You could provide a 12 volt feed to the output side of the pump fuse F5 from memory and run the pump for longer to see if the pump quites down and post back but tell me what engine code and model of passat you have. Regards Peter

[passat 130 tdi]

my 2001 pd does it also - not worried

[bv123]

Hi Peter,

Sorry, I should have said - mines is a 2004 Golf Mk4 1.9 TDI. I replied to the orignal post after I found it doing a search so didn't realise it was in the Passat forum.

Not confident in trying the 12 volt feed to the output side of the pump fuse F5 (if its still the case for a Golf Mk4), but after the engine has started, the pump hums barely audibly, so I guess its running as it should.

Does the pump provide pressure all the time while the engine is running or just during startup?

R,
Bv

[venetian-red]

Guys, the cars fuel pump will always make this noise, it is normal and nothing to worry about.

[bv123]

Not worried (as car runs fine, gets me to work etc)....

....but I am concerned because of this awkward fact - old pump wasn't making this noise but new one is - being an engineer I need to understand

Anyway, I have filled up tank to 3/4 and hey presto - no more squish, squirt, flush noise!

Will see at what tank level pump needs to go to the loo again.

[Peter D]

I suspect that air is entering the system when left for a period of time and that is the cause of the noise. Air can enter in several places without showing a leak. There are also some connectors and seals associated to the pump inside the tank that may be letting air into the system. After 6 or 7 years the flexi fuel pipes, particularly under the bonnet as they get hot, perish and minute cracks appear on the inside of the pipes under the clamp, like those on the return pipe. Left overnight air enters the system, or the return valve and fuel drains back to the tank thus the air. Regards Peter