Wired Rattle Noise from Fuel Tank Area

[Kocho]

Can you try this: park the car in a quiet place, then gently shake the rear side to side by pushing to top of the car to induce quick side to side wiggle (mainly due to the tires wiggling, no need for the suspension to move).

Do you hear what I hear? There is a noise coming from near the fuel tank area (I guess) under the car, probaby a bit more to the passenger side and a little forward of the rear axel. Sounds like a wheel bearing ball is rolling back and forth inside somewhere. If I shake the car even more, I begin to hear the sloshing of the gasoline in the tank too. But this rattle I describe comes with barely any shaking and when I can't yet hear any sloshing in the tank.

I don't think I've noticed that before...Any idea what it might be? Perhaps some baffle in the gas tank is moving with the fuel pushing aginst it?

I can't see anything lose and the noise does not seem to be due to suspension or wheels moving either. It only needs a very gentle shaking sideways to induce (can do it with one finger pushing to shake the rear of the car side to side on its tires)...

[Kocho]

Interesting... Just lifted the car to see if there is anything loose under there and I can't see anything... The plastic underbody panels that cover what I think is the gas tank (area directly infront of the rear axel) had lots of pebbles in them so at first I thought maybe a little rock got in there and would roll when I shake the car. But I shook the sand/small stones off and the noise is still there - coming from the area above these panels.

Unfortunately, when I lift the car I can't shake it (it is firmly supported) so I can't reproduce the noise. And when it is not lifted I can't get under it (too low) to precisely pinpoint where the noise is coming from. It is coming from the underbody somewhere (not from inside the car or the trunk) and sounds like there is something lose in there...

Will be going to the dealership I suppose, since this does not sound normal - the slightest shake of the car and I hear it rattle...

Just curious - can someone else shake their car and listen to see if they got this kind of noise? As I said, just park it in a quiet area then push the rear sideways to wiggle the rear end over the tires... Thanks!

[Kocho]

Definitely has something to do with fill-up at the gas station. Filled-up again yesterday and heard the noise. Once the level of gas in the tank goes down a bit (after sau 40 miles) the noise diminishes/disappears.

I'm not over-filling, only filling-up till the pump clicks and usually put less gas than I think the tank can hold max.

So, at your next fill-up, shake the rear of your car and see if yours makes the noise. Note again that this is not a sloshing noise that you might get with a big shaking motion of the car - it is more of a subdued rattle noise that is audible with even a very gentle side to side wiggle at the rear end.

[AClewell]

This is just a guess but it may be the fuel level float. The gas would make it move even if the gas was not sloshing. If it is only doing it when full the float may be topping out and striking something until the fuel level drops.

If it was my car I probably wouldn't worry too much but thats just me LOL

Good luck.
Alan

[Kocho]

Good thinking about the float. Might as well be that...

As long as it is not causing anything bad I would not worry either. I just don't like things rattling if they shouldn't

Since I'm not sure if it is like that with every car or not and is instead something lose in mine rattling in there creating debree, I am still a bit worried...

I'll see if it gets any different over time before I let anyone touch my car at the dealership and mess with the fuel tank

Thanks for the note and I'm still curious if Gen II owners can do the simple shake and listen on their next fill-up and share results here.

[Willie Williford]

Float level hitting the top of the gas tank when full.
Next fill up leave a little room in the tank (1 gal) and check again.
Thats where I would go.

Willie
Or overfill it a little and see if the noise goes away.

[Kocho]

Here is a little video so folks can hear the noise. Very little shaking of the rear of the car is needed to produce the noise. It is definitely coming from the fuel tank area and is not related to suspension noises. Everything external is tight.

2011 Honda Insight Gas Tank Rumbling Noise - YouTube

I'm still curious if others are experiencing this noise. Please shake your car next time you fill-up. As long as you are in a quiet area you should be able to hear it.

If you hear gasoline sloshing but do not hear the rumbling noise, then you are shaking more than strong enough and you simply don't have this issue. In my case I begin to hear the rumbling noise before any sloshing noises become audible and it continues once I stop shaking the car and subsides a second or two after the sloshing noise subsides. I only need to shake the car gently with two fingers or one hand at the rear to hear the rumbling and if I do not shake strong enough, I hear the rumbling but I hear no sloshing...