Nancy Gil

I have a 2002 I-35 and when I parked it and turned it off I heard a humming noise coming from the Gas tank area.Never heard that sound b4.. I popped open the tank and felt the fumes come out noise stopped after. Is it possible the pump is staying on??

mayur914

iTrader: (7)

The fuel pump is on only when the key is in the "on" position from what I know. Not on when the key is out of the ignition.

DennisMik

iTrader: (2)

I think what you are hearing is the gas tank's filler cap. When the car is running, engine vacuum is used to suck the fumes out of the tank. When you turn the car off, the gas cap slowly lets air into the tank, so when you opened the gas cap and let air in quickly, the sound stops. This is normal.

Nancy Gil

Thanks guys! I work the auto part industry and one of those girls who likes working under the hood, But this noise was new to me it still is doing it and its not very quiet that humming sound (more like a super quiet alternator. My friend said its possible that the FP has a short also the o2 sensors (all4) are out is can this be a contributing factor?

DennisMik

iTrader: (2)

O2 sensors would not play any part in this. Besides, if the O2 sensors were out, your check engine light would be on with a code for each sensor.

If you want to prove or disprove the fuel pump running, pull the fuse out for the fuel pump. It is F29, the bottom row, 3rd one from the right, 15 amp.

But I'm pretty sure this will not stop the noise for several reasons: the power to the fuel pump is cut off by the ignition switch when in the off position. The ECU would have to keep the fuel pump relay energized. This means you have to have a bad ignition switch and a bad ECU. Lastly, and most conclusively, the noise stops when you open the gas cap.

Maybe if you try a different gas cap, the noise may go away, but it did not stop my car from making noise.

And lastly, the fuel pump cannot be doing it. With the power shut off, the motor would have to be running on perpetual motion, something the laws of physics don't allow.

And whoever said that the fuel pump could have a short.. well, they have the electrical knowledge of a rock, if that much. If something shorts out, it will draw many times the amount of electricity that it is supposed to. The result of this is blown fuses, burned wires and fires. An example of this would be to take a piece of wire and touch the ends to the terminals of a battery. Smoke and fire will result. By the way, DO NOT hold the wire with your hands when you do this. /rant

ABIGBRAIN

iTrader: (1)

Radio antenna going down? From the drivers' seat, the antenna motor in the rear quarter panel, is nearly in line along the same angle.

Nancy Gil

@dennis, thanks u have been very helpful! Saved me $$ lol@ knowledge of a rock.. Hahaha... I will replace the gas cap since the noise does cease when i open the cap.. It is now a pain to put back on for some reason the compression makes it hard. Do u have a i35 i would love to have a manual for my car.
And yes the check engine light is on. Sensors bank 1&2..among other codes..

1992maximase30

It's something to do with the evap canister. The 3rd gen maxima commonly did this. I had this same noise there's even a thread on this.