XYZLexus1

Your problem is the roll over check valve on top of fuel tank. Part number 77390-30071 for valve and 77177-33010 for gasket. It is located on top of the gas tank and a real motherfuker to get to from underneath. You have to removed exhaust, heat shields, drive shaft, lower tank about 8 inches and fight like a biatch to get the connector off. It took me 4 hours with a full shop of tools and lift. the easier and better solution is to study gas tanks on eBay to identify where the valve is ( Passenger side just left of drive shaft hump towards the front of the tank) and then carefully cut a hole on the floor board after you the rear passenger seat. there is a video on you tube that a guy does this on an IS 300. Location appears to be the same but part numbers are different. Use what i wrote above. Mine would stink like fuel also and randomly throw a P0440 code. they crack on top, i couldn't see until i soaped (after removal) and blew in the little hose connection, the whole thing is cracked. Everybody is probably cracked. If emissions were so important they should make them life time warranty, then they would be designed not to fail!!!!

Mr Jokster

iTrader: (8)

Not necessarily. That code could be something as simple as a bad gas cap. There are 10 codes for the evap system and most of them can also be the purge valve.

READERS do a process of elimination before going through the trouble of this repair.

As for the swap, yes that may be the 'easier' way, but when I did mine, I didnt remove anything, just a lot of hand twisting and some curse words

XYZLexus1

I Agree P0440 can be gas cap, bad hose or roll-over valve described above. If you have the ability to replace the valve you would have done the other due diligence. It would be absolutely impossible to replace the roll over valve without dropping tank or cutting hole in floorboard, Its 2" in diameter and 4" long and on top of the gas tank. You must be referencing the VSV valve which is not a code p0440 but a P0442 or P0446. I could not see any cracks on mine when removed, thought maybe i missed the problem. I soaped the top and blew in it and the hole top has a hairline crack around the base. Getting the big hose connector off the top was a nightmare, ****ty design....

Gdwrench35

I can't stress this statement enough. Nothing like spending hours upon hours under your car performing a pain in the **** repair, finally get it done, and find out your issue still exists. POSITIVELY IDENTIFY THE PROBLEM before you replace anything.

Thank you Mr Jokster for pointing out what I've been trying to stress to everyone on this forum since I started here. Don't blindly throw parts at the car on a whim or someones advice on here. I can promise you that while I'm sure the intentions are good, its impossible for anyone to know that your roll-over valve is bad (not very likely) from a description of a gas smell and a code. I can think of half a dozen or better other issues that will cause the same symptoms and fail far more often than the roll over valve.

XYZLexus1

i did blindly throw a part after it after researching. I was right. The problem is it is a design defect. The is 300 and gs 300 will eventually all fail. I have a texas car, all hoses pliable and soft, all grommets easily unsnap yet they top of the roll over valve failed. I don't see how it is under any stress, in fact it is very protected once installed on top of the tank. My bet is if its isn't the gas tank cap, it this valve, the hose are all protected from UV rays under the car, operating temperature is ambient. After about the 4th post i read p0440 from hell this always turned out to be the culprit. The only way you will see the crack is to soap it and watch the bubbles blow. I cannot stress enough remove rear seat and cut an access panel carefully and this would be a 45 minute job. Again i guy on youtube did it for an is 300 but he calls the valve the wrong thing he calls it a vcv valve. Those are located on the charcoal canister behind the fuel tanks and under the hood.

Oh for grins I did replace the gas cap before i did this. My car is a 2001 lexus gs 300 with 124K miles on it.

One other thing is I WAS GETTING GASOLINE SMELL next to the passenger rear wheel and rear door!!! It was random but one day it stunk and at that point i had to investigate. If i would have not smelled the gas I probably would have just reset the code waited until all but the evap system was ready and got it inspected. in texas you can have one system not ready but you can't have one that has failed. i think the gs 300 has 6 systems. hate to play games like that but they should either design the components better or being able to self diagnose better..

Mr Jokster

iTrader: (8)

Ah yes, you're correct. I was thinking about the vsv

XYZLexus1

Attached is an image of the roll over valve. the part i cut away is what had the crack around it base. it appears the cars either pulls a vacuum or pressurizes the top piece to test. it is this that fatigued and failed the cheap plastic around the base.