Baby ///M3

Recently, I've heard some weird sound from the rear seat passenger area.

It seems as if the noise is coming directly from the gas tank but I could be wrong. I just know that it's coming from the rear and this noise is not very audible at all. For those of you who's owned a fish tank before, this noise is almost identical to the water flowing sound in the tank.

This only happens within 10-15 seconds right after I start up my car and it does NOT happen all the time. Only once in a while. And as soon as I let the car idle for a bit, the noise goes away.

Does anyone know where this noise comes from and what might have caused this?

My car's currently running in very good condition. I just had the timing belt/water pump/tranny mount replaced and it runs like a champ.

Thanks in advance.

Jon

mmarshall

Is your fuel pump inside or close to the gas tank like on some cars? If so, that could explain the noise on start-up...especially on a cold start when the engine is running full-rich for about the first minute or so. An old or weak fuel pump with worn bearings could make funny noises when it is working hardest.....on cold starts or during periods of high engine load when the demand for fuel is greatest. When you warm idle, the demand for fuel goes way down and the pump barely has to work at all....hence the lack of noise at that time.
Of course, there are other possibilities as well, but that sounds like the most likely one.

Baby ///M3

Thank you very much.

You're just as helpful here as you are in the car chat forum! I mean it in a good way too!

If I remember correctly, I was told a while ago that my fuel pump is somewhere in or near the gas tank. I hope it's not dying on me now. It would suck to be stranded in the middle of nowhere due to a faulty fuel pump.

As long as there's no risk of my gas tank blowing up on me, I am good to go.

Jon

setwire

Preventive Maintenance is the key to not being stranded,
I would remove the rear of the back seat, remove the access cover to the fuel pump and have a listen.
If it is a noisy fuel pump I would think about replacing it before you do get stranded in the middle of nowhere.
Takes about 10 minutes to remove back of rear seat and fuel pump access cover.

Rob

/Aerostar\

iTrader: (2)

Yea the fuel pump is directly behind the upper rear seat. Definitely look into replacing that. You could upgrade to Walbro, but apparently those are alot louder than stock

lexsc492

i've also been hearing these noises recently.
glad this thread came up

mrshabo

I'll sell you my pump for 20+ shipping and paypal. i have 85k on it. PM if interested.

salimshah

Another thing ot consider is how much gas is the tank. The accoustics, change with amount of air. Also if you are too low on gas you can be pumping bubbles ... like sucking up from a straw with only ice in the fountain-drink-cup.

Also the pumps are happy when they are submerged in gas (keeps them cool). One of the reasons to keep the tank 3/4+ full.

Like all things the pumps have limited life. I would be unhappy to replace the pump before 100k miles.

tip: Fuel pump electrical control has a safety mechanism built in, they sense if the engine is turning (running). In case of accidents, (when the engine is not turning over) the pump is shutout by the safety.

Salim

Nomis

I hear a "bubbling" sound from my tank on occasion - the weird thing is that I sometimes hear it when the ignition is off as well. It may be air in the fuel return line bubbling up? Does that make sense? I'm pretty sure there are quite a few other members that have the same symptom - without any adverse effects.

JLSC

Same gurgling noise from my gas tank area and it only lasts for about 20 seconds when the motor is warm. The noise never occurs on a cold start. I replaced the fuel pump but that didn't make any difference. The local Lexus dealership suggested that there is probably a fuel pressure problem and recommended replacing the gas gap, which I also did but there was no improvement. The motor runs fine so I've let it go for now.