Chasing the code, help please

[ghost111]

I'm still chasing PO446 on a 1999 Camry V6. VSVs test fine, can't find any bad vac hoses. However when I remove the gas cap [which is new] I do not hear the customary "woooosh" or burp. I am wondering if there is some connection there. Like a filler pipe vac leak or some sensor hidden on top of the fuel tank.
Your thoughts please.

[BamZipPow]

You might have a rusted filler pipe? Have you smelled any gas fumes?

[ghost111]

No rust. This is a Florda car so the underside is pretty clean.

[CamryConvert]

With the VSV in non powered state - you can blow thru it one way and not the other, with it powered - it goes the other way?

Perhaps the ON signal never gets to the VSV, broken wire, bad connector, etc. - Connect a test light to the wires near the switch and see that the light comes on before it sends the 446 code. Run the wires in the window, tape the light to the dash. (wouldn't it be nice to have the Toyota OBD tool that can command the Brain to send the ON signal to components?)

To check for leaks you can use the output of a shop vac to lightly pressurize the tank - and everything else. Use duct tape - but make the connection leaky so as to not blow things apart. A spray bottle filled with kids bubble soap can be used to find leaks in places you can see but not really get to. - poor man's smoke generator.

You can

[ghost111]

Can anyone tell me there is supposed to be a "woosh" sound when you remove the gas cap? I do not hear it and it seems there should be.

[BamZipPow]

Originally Posted by ghost111

Can anyone tell me there is supposed to be a "woosh" sound when you remove the gas cap? I do not hear it and it seems there should be.

I guess it all depends on certain conditions. Outside temp, fuel tank temp, how much driving before opening the gas cap.

This new gas cap...is it a Toyota one or some aftermarket one? Did you carefully check ALL the vacuum hoses from the tank to the evap canister?

[ghost111]

I have now purchased and replaced the VSV on the charcoal canister. And P0446 came back after a reset. How many VSVs are there? I know there is one under the hood near the airbox but Autozone and Advance Auto don't carry it. Is it dealer only? Also I have read there is some other sensor on top of the gas tank. How do you access that one? [from the rear seat maybe?]
I am not getting any other codes in conjunction with this one.
THX

[hzt30]

Originally Posted by ghost111

Can anyone tell me there is supposed to be a "woosh" sound when you remove the gas cap? I do not hear it and it seems there should be.

You should be able to hear a "woosh" when removing gas cap after car has built up enough pressure and you don't have a leak. I have a 1991 Camry and I definitely hear the "woosh" sound but this is OBD-1 and there is no check for this.

Did you check the vapor pressure sensor? It is located on the top of the cannister not far away from the VSV. The following procedure is out of the service manual:

INSPECT Power OUTPUT OF VAPOR PRESSURE
SENSOR
Turn the ignition switch ON.
Disconnect the vacuum hose from the vapor pressure
sensor.
Connect a voltmeter to terminals PTNK and E2 of the
ECM, and measure the output voltage under the following
conditions:
(1) Apply vacuum (2.0 kPa (15 mmHg, 0.59 in.Hg)) to
the vapor pressure sensor.
Voltage: 1.3 – 2.1 V
(2) Release the vacuum from the vapor pressure sensor.
Voltage: 3.0 – 3.6 V
(3) Apply pressure (1.5 kPa (15 gf/cm2, 0.22 psi)) to the
vapor pressure sensor.
Voltage: 4.2 – 4.8 V
Turn the ignition switch OFF.
Reconnect the vacuum hose to the vapor pressure sensor.