'01 Monte Carlo; vent valve location

Hi. I've got a 2001 Monte Carlo LS with the Check Engine lit, spitting out a code of P0440 (I've got my own OBDII scanner). It has been lit since I
bought the car and everytime I clear the code, it comes back at least two days later, or the first highway trip the car takes. Even when the code is erased, the emissions status on the scanner is still showing yellow, which is mid-range. I've determined that the purge solenoid and the fuel pressure sensor on the sending unit are not the cause of the code by switching them out with known working good parts. My next step is to check the vent valve and lines running to the canister and vent valve. Where exactly is the vent valve located on the fuel tank? Is it accessible by removing the access panel in the front part of the trunk (this lets you access the sending unit on top of the tank without lowering it). I dont't remember seeing anything similar to a valve when I replaced the pressure sensor. Or would I need to lower the fuel tank to get at it? I thought I read in an internet forum that access was gained by removing one of the rear wheel inner fenders, but I don't recall which side of the car. A clear answer to this would be very helpful, and possibly save me a lot of extra work.
Any help to locate this part would be greatly appreciated. Also, I'm looking for a part number for the vent valve, I'm having trouble finding one on any internet parts store.
Thanks, Sharky
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This may sound silly, but every vehicle I have scanned, that came up with that P0440 code, only needed a new gas cap. I would give it a try, it's only a few dollars and could solve your problem.
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Hi. Forgot to mention that I have already switched out the fuel cap and it made no difference. But thanks anyway,
Sharky
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I'll throw something else in too, not that it matters to your car's condition. You said that when you clear the codes, the OBDII scanner still shows yellow. That is normal. It shows yellow until the computer runs enough cycles to either register as green, or go back to red, and illuminate the Check Engine light, showing you the P0440 code. One last thing. Did you check the fuse box to make sure the fuse for the vent solenoid hasn't blown? From research, that is a common problem as well. If you are still having trouble, I would take the car to a shop and have a smoke test done. You likley have a leak somewhere, and replacing parts randomly isn't going to fix it. It could just be a small o-ring.
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No, I don't think I ever have checked any fuses for the solenoid. I didn't realize there was a fuse for it. Don't suppose you know which fuse panel it is on, right off hand? There's one on either end of the dash, and a distribution block under the hood. I'll have a look in the manual as well, should be listed in there. If it isn't the fuse, I'm still going to look for the vent valve and at least check it visually, and the lines going to it.
As far as the yellow light on the scanner, it always goes back to red once the CEL comes back. But the fact is, 3 of the tests never complete until the p0440 comes back, and then, of course, it obviously fails ands sets the CEL. When I switched out the pressure sensor, the fuel cap and the solenoid, all 3 times the tests never completed when I erased the old code, which told me there was still something wrong. BTW, my brother-in-law has a junked Lumina with the same engine that I am switching the parts from. The car runs and there is no CEL on in his car.
Thanks for the help thus far. Sharky

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Just checked the fuses and they are fine. There are two, one on the drivers side panel (ABS, PCM) and one on the lower engine fuse panel (Engine Devices). Just to make sure, I switched each one of them out with a spare and it didn't make any difference.
Oh well, looks like I'll be searching for the vent valve.
Sharky
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replying to Sharky, Rocky wrote: Located on the driver's side by the fuel fill kneck you can access it from underneath the car
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Rocky wrote:

Finally, 6 1/2 years later, Sharky gets an answer.
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