RPMulli

My car makes a howling noise from the front end coming from the gas cap area. At first i thought it was the fuel pump, so i replaced it and the howling continues...

I noticed that the howling only occurs when i barely step on the gas pedal, then as soon as i left off it disappears. The noise also goes away after i step on the gas pedal beyond the "barely step-on" point.

Note: the A/C is never on when this occurs.

Is there some sort of pressurization system in the gas tank? what are all the components forward of the battery besides the fuel pump and radiators?

Thanks. Any diagrams of the fuel system or vent system would be great as well

RPMulli

I have a 2000 Carrera 2 by the way.

Tom M

Here's an old post (circa 2002) from RobynC at Babblers that, I think, covers what you are referring to.

As noted in the response, I ran into the same problem on my 2000 Boxster S. The best I could describe it was the "Coke bottle" sound. Was very sensitive to throttle position. It would happen for me when I was just lightly cruising along and any additional throttle would make it go away. The dealer changed the valve and the problem disappeared.

RPMulli

i think you hit it on the head, that is exactly what is sounds like... what valve was it? where is it located?

RPMulli

is this it?

http://www.pcars.com/porsche_parts/s.../p_146116.html

Tom M

I don't remember off the top of my head. I'd either have to pull out the old work order to see what was replaced or take a look at the PET diagram. I can do the former when I get home unless someone else comes up with the answer before then.

RPMulli

sounds good, i bet its just on top of the fuel tank where those lines are on the passenger side near the battery. id have to look after work.

fpb111

Is it only during the full moon or does it happen with the new moon also? If there are other 996 around do they start answering? Did you take your meds today?
+1 for the tank vent.
Had something similar on a 72 with 1/2 of the evap stuff removed. It was more of a high pitched whistle on that car.

RPMulli

i looked at the PET. im not sure how accessable this valve is, it looks like it is forward of the battery.

Shark Attack

My wife does this sometime late and night ane only if everything is working right... It means you are really hitting the right spot.

mavthenav

She needs a pillow....

Barn996

Nothing like a sreamer...

Pac996

Could be the way the gas noozle flap seals so good. I've tried pouring injector cleaner additive in and its a pain having to hold the flap open to get the stuff into the tank. What I'm thinking is with the gas being drawn out of the tank air has to enter and going past a good seal on that flap it might be acting like a reed in a horn section of a band. Maybe a slight roughing up of the flaps rim would solve it. I figure a red hot poker through it is out of the question

Tom M

On my 2000 Boxster S the p/n was 996-201-231-01. Based on the price that's a bad thing and I would learn to live with it

http://www.pcars.com/porsche_parts/s.../p_136152.html