Xavier56

Hello All,

I think the Gas Tank Vent line is Plugged some how. During a Fill up it is very difficult to fill without pump clicking off.

It is not the Gas Station I have been to a few different ones and same issue, I have read some posts on this and cannot find a clear way to fix.

First - How can the Vent Line get plugged?? and with what?

Can this be caused with something to do with Evap Canister?

I have read to use Fish Tapes to clean out vent, use Air Pressure (which some do not recommend), Replace Gas fill line with New One.

I looked at the New Gas Fill line tube on line ( see picture)

I see three Tubes all different sizes - Large one is Gas fill - Then there is two smaller ones - One large ( figure that is Vent line) and one Smaller.

Does any one know what the smallest on does and where it goes ?

and the best way to test and fix this issue?. Thank you


.

Fit1too

I believe it goes to the 'fill check valve'.

salimshah

It is the Y very near the fill cap.

Salim

Fit1too

Using this pic and the diagram above, you can see that they both go over to the top of the fuel tank. Not sure which one goes to what. In comparing this picture to the diagram, it looks like the big line/pipe goes to the Fill Check Valve. Not sure what the other pipe is attached to, wish it was labeled. No matter, I wouldn't blow any air in the them.

Xavier56

What about trying to suck on them. Not sure you can even do that if you tried,

Then I cannot see how you could a get a fish tape down any of the smaller ones to clear out . They come in at 90 degrees.

And what could be plugging it??

Wish someone that had this same issue and fix it would chime in - Please

Thanks

salimshah

One can rig up a tubing to a vacuum (shop-vac) and try to snake the tubing into the vent hose.

I have come across about 10 or so complaints.

Not sure if it happens due to overfilling, but that has been extended as a reason.

It might be worth calling Lexus and taking to the service advisor to see if they can suggest a fix.

I have never dropped the fuel tank so it is fear of the unknown, but I would not recommend it if a person is working alone on the vehicle due to limited space/clearance in home garage and the bulk of the fuel tank [has to be empty too].

Salim

Fit1too

I agree with contacting Lexus (or Toyota) and getting some pointers as far as which way to proceed. Also, agree about dropping the fuel tank. I dropped one on a 94 Eldorado to change the pump. It was pretty straight forward, BUT I had a lift, a big floor jack to guide it down, lots of space, a friend on standby, etc.
I've researched high and low and have found limited information on this subject as far as EVAP codes like P0440, P0442 and P0446. I found zero info about dropping the tank on a RX300. There is information about the codes, but only so much i.e. change the cap, change the VSV, change vacuum hoses etc. Some have changed the canister, but it is pricey. Not going the throw parts at this. The OEM fuel cap was about as far as I'm willing to go (or throw as it were). Found info on using a smoke machine, but no answers for what to do about the stuff on top of the tank i.e. fuel filler check valve, pressure sensor, and/or cut off valves.
Reality is, I'm limited on knowledge in this (EVAP) area, have no work space, and no time. Will probably have my guys at Toyota look at it. I don't like having a check engine light on. In all 50 plus cars, this is a first for me. I see others having check engine lights and VSC/TRAC lights pop up, but I've been blessed in this area. The check engine light has come on ONE time in 12 plus years and 190K miles on my 98 RAV4. It was a VSV for the EGR- $20 bucks!
I'm going to put together a document on the research I've amassed on the EVAP system and related codes. Maybe the site will create a sticky.

BobQ

I had a similar problem with a Sonata where the evap canister allowed the carbon pellets to escape (common problem in Hyundai). The pellets got into the fill check valve causing it to lock in the "full" up position. Luckily I could disassemble the "fuel check valve" and clean it. Problem returns if the rest of the system is not cleaned and evap canister replaced. Since the problem is not common with the RX300 I'll assume something else is the problem. But still related to the "fuel check valve" which has a float in the tank that lifts and blocks air/vapor from escaping when the gas level is within a couple of inches from the top. that makes the fuel back up the filler tube and stop the pump handle. The fuel in the fill tube then flows back into the tank as there is a little room left for it. Also the escaping displaced air/vapor from the tank passes through the evap canister where the fuel vapor is absorbed by the activated charcoal pellets. Then as you drive outside air is sucked through the canister (cleaning the fuel from the charcoal) and into the engine where the fuel is burned and the evap canister is readied for the next fillup. All this is to say I'd take a look at the "fuel check valve." You might even go to a You-pull-it place and take apart a "fuel check valve" just to see how it is put together before looking at your own. Also get a handle on just how much trouble it is to disassemble. BTW in hind sight I should have cleaned the "fuel check valve" and then inserted a cheap clear plastic fuel filter. That would keep contaminates out of the fuel check valve and prevent future problems. The filter can be placed where it is easily accessible if the problem returns.
Please fill us in on what you learn.

Fit1too

Excellent synopsis of the fill check valve operation. I’ll write something up when I’ve achieved success. I have learned a lot about the EVAP operation, but wish I had the proper equipment to diagnose the system correctly. I have a basic scanner, but want one like the guys use on these Youtube videos that activate the VSVs and show the vacuum pressure etc.

Also, there are ‘early’ (non-intrusive) and ‘late’ (Intrusive) EVAP systems on 1996 model year and later OBDII equipped Toyota and Lexus vehicles. The 1999 is early and 2000 and beyond are late, but according to the info I have found on the charcoal canisters, there are 3 different versions depending on the build date.

And finally, to make it even more complicated, Toyota (and other car manufacturers) use a ‘Readiness Monitor” to monitor the performance of emission-related components. This is why many people “think” they have solved their issue only to have the check engine light pop back on a few days later. I’ve read soooo many posts where people say they took their car to so-and-so and had their ***______ changed and then 2 days later the check engine light was back on. They feel ripped off, cheated, lied to, etc. Reality is that since the various components need to be monitored separately during different driving conditions, the OBDII system is designed to run separate monitoring programs called Readiness Monitors. Example: for the EVAP system the following criteria must be met before the test will even run.

· Cold soak procedure performed: Start engine and allow coolant to reach 176 degrees or greater, and then let vehicle cold soak for 8 hours or until the difference between IAC and ECT is less than 13 degrees

· MIL light off

· Fuel level between ¼ and ¾

· Altitude 7800 feet or less

· ECT (coolant temp) between 40 and 95 degrees

· IAT (intake air) between 40 and 95 degrees

Then there is a drive pattern! I won’t go into that, but it is easy to see why proper equipment & know how is necessary. It’s also easy to see why it seems like a problem is fixed, when in reality it is hiding. Examples: if you live in North Dakota and an EVAP line busted or rusted through during the winter, you probably wouldn’t know it until Spring when it warms up enough for the system to monitor itself. If you constantly run low on fuel… If you live in Saudi Arabia during Summer…

Oh, and another thing, the issue must happen twice before the check engine light illuminates! That’s all my brain can handle tonight. Hopefully I have mine fixed, but I need drive it for a few days to meet the above-mentioned requirements and it’s supposed to get cold tomorrow night so……

Xavier56

Quick one - when I changed the Evap Can I can hear pellets moving inside it. So maybe some got out into tank hardware some how.

Will look into that too.

The weather here has turned for the worst here we had 15 F the other night when it should be 34 F at the lowest.

So was not ready for that with that cold outside stuff ( garden hoses, Fountain, Pool leaves) so been trying to get all done before can go back to the nightmare RX issues.

Thanks for everyone help.