Hisssssssssssssssssssss

[Alexlind123]

My car has made a hissing noise from the fuel tank area for some time now, but i previously assumed it to be my leaky muffler. I have now discovered that the muffler was NOT the source of the noise.

The fuel tank does not throb, and the sound continues when the gas cap is removed, even when the metal gate is pushed aside.

Occasionally, i have noticed a faint gas smell around the filler area as might be caused by careless filling. However, i am meticulous about my fueling procedures, and the few times which i have dripped i have carefully cleaned up with the towels of sponges that service stations so often keep handy.

[tnt525i]

are you sure its not the fuel pump you're hearing?
switch off the car and check for the hiss

[wjbell]

It's probably the fuel pump. It's normal, mine does the same thing. Sounds like air leaking. I've always equated it with a luxury car, as I've only heard it on BMWs and Mercedes.

[SchnellE34]

Yeah, most definitely the fuel pump. I have had the hiss for about a year now. Its a very common thing for the e34. Turn your key to the 2nd position and listen for the noise. The fuel pump is on the passengar side of the tank. It may just be a dirty screen on the pump. I cleaned mine but no luck. Just plain needs to be replaced. I would recommend removing the fuel pump only when you have less than a quarter tank of gas, less messy that way.

bmwe34.net has more info on removing the pump.

[wjbell]

Yeah, most definitely the fuel pump. I have had the hiss for about a year now. Its a very common thing for the e34. Turn your key to the 2nd position and listen for the noise. The fuel pump is on the passengar side of the tank. It may just be a dirty screen on the pump. I cleaned mine but no luck. Just plain needs to be replaced. I would recommend removing the fuel pump only when you have less than a quarter tank of gas, less messy that way.

bmwe34.net has more info on removing the pump.

I don't think the hiss means it's going bad, it's just the normal operating sound.

Mine's been making that sound for almost two years and have had no fuel related problems.

[gmannino]

I get the hiss also.

[Mr Project]

The pumps are pretty noisy, though they get worse as they age and when they are near death. :) If it starts getting louder, I'd consider picking up a new one to have on hand for when it dies.

[Jon K]

Mine hisses and makes the 45 psi it should @ idle.

[colo525i]

My 525 has done this, same with my old benz 190E. Neither has ever had a fueling problem. Bosch fuel pumps just get noisy with age, they'll only die if you don't change the fuel filter.

[632 Regal]

am I the only one with a silent pump? cant hear a thing...ever

[angrypancake]

i hate the hiss. jeff since when did you become a moderator

[632 Regal]

why? you notice people disappearing?
jeff since when did you become a moderator

[wjbell]

My 525 has done this, same with my old benz 190E. Neither has ever had a fueling problem. Bosch fuel pumps just get noisy with age, they'll only die if you don't change the fuel filter.

Where is the fuel filter located? I'd like to change mine just in case..

Heh, I owned a 93 190e 2.6 and sold it to buy my 90 535i. It made the same sound too.

http://www.belletc.net/test/93-190-new-1.jpg

http://www.belletc.net/test/93-190-new-2.jpg

[632 Regal]

fulters behind the right rear tire up behind the wheel well. Prepare for a gas bath.

[Alexlind123]

Thanks alot for all the helpful advice! I have replaced my fuel filter and my prefilter is flawlessly clean.

When you replace your fuel filter, pull out the fuel pump fuse with the engine running to drain out the pressure in the lines.

[SchnellE34]

I just clamped the lines before and after the filter to reduce spilage. I don't think mine had ever been replaced. I have been getting one mile per gallon better ever since replacing the filter. Make sure you have new hose clamps.

[Thayne]

am I the only one with a silent pump? cant hear a thing...ever

Same here. My last E30 did this but the E34 doesn't.

[KenB]

Same here. My last E30 did this but the E34 doesn't.

My e34 is silent also, my e30 was noisy and my e28 and e21 weren't.

[skr]

am i the only one without a prefilter? is it a diesel thing? i searched and searched and there's nothing n the lines from tank to engine compartiment. but i got a big ass fuel filter just before the injection pump. probably can hold 1,5 liters of fuel :) Should i install a prefilter on the line somewhere?

[colo525i]

Every diesel my family has owned has only had filters up in the engine bay, right before the injection pump. Never seen a diesel with an electric pump right by the tank just like the gas cars have.