[Bitter]

most charcoal canisters are ruined by topping off the tank with gas, theres a level at which the vent in the tank becomes submerged. once its submerged then any pressure in the tank pushes liquid fuel into the canister which can cause some pretty nasty things if it gets really badly filled with liquid fuel.

cramming in an extra $1 of gas could cost you several hundred $1's later on.

[Anton]

This week I got some time to work on it. I took out the Cannister and replaced some of the hoses (most of the smaller ones.) Also I replaced the VSV on the cannister. I cleared the DTC's and they stayed clear for about a week, then returned. Actually, I haven't checked to see that they are the same codes.

I may have topped off a few times. Now I know better, and I make a point of telling any gas station attendant about this as well. Also, it is a used vehicle, so the damage could be more than just mine.

I have to go under again just to replace the bracket on the muffler. It was pretty rusted up. anyway, I don't know if going to a junkyard for a cannister would be useful, because they could be ruined from topping off. How could I tell if the cannister was messed up without installing it? I guess I could pull codes from cars at the junkyard, assuming they would still have the ignition, ecu, battery... :rolleyes:


Anton

This topic should probably be in 'corolla general', if the moderator could please move it there, thanks.

This post has been edited by Anton: 31 March 2006 - 05:53 PM

[fishexpo101]

Hard to tell from salvage yard pieces - check for physical damage first. Any cracks = dead vapor canister. Sometimes you'll be luck and find a canister filled with liquid gas (usually) = not salvageable. Other times the canister was saturated with gasoline, then had it evaporate later - still not salvageable, since the activated charcoal inside will be ruined once liquid gas gets in there.

Better off to get a brand new one - seen them a slow as $160 online for a brand new OEM part.

[Bikeman982]

What kind of a bad design is that - charcoal cannister gets ruined by topping of fuel?? I try to get as much fuel as I can into my tank at every fill-up. I drive 100 miles a day and it doesn't take long to need a re-fill. At least my cannister is under the hood and isn't affected by a full fuel tank.

[fishexpo101]

Actually - the design is pretty elegant for what it accomplishes . The canister is much smaller and flexible (computer control) than previous designs - but with a smaller canister, any "oops" will not be able to be absorbed by the system. They even tell you not to top of the tank in the included documentation - but its hard not to resist craming an extra gallon or so for that extra 30-40 miles or more range.

[Bikeman982]

fishexpo101, on Apr 1 2006, 12:28 AM, said:

Actually - the design is pretty elegant for what it accomplishes . The canister is much smaller and flexible (computer control) than previous designs - but with a smaller canister, any "oops" will not be able to be absorbed by the system. They even tell you not to top of the tank in the included documentation - but its hard not to resist craming an extra gallon or so for that extra 30-40 miles or more range.

How could they have designed it so that it would not be affected by a "Topped-off" tank?? Seems like that would have been better.

[fishexpo101]

Bikeman982, on Apr 1 2006, 01:00 AM, said:

How could they have designed it so that it would not be affected by a "Topped-off" tank?? Seems like that would have been better.

I'm sure they do have a better design (2003+ Corolla are not a susceptible = more expansion room and anti-siphon feature) - but bean counters will always have the final say. NOte this also affected many arly Prius models - but they also had a worse time, sometimes the gas gauge would be way off.

Doesn't matter how many warnings you stamp all over the car - people will do whatever is more convenient for their current needs. Things to keep in mind when "topping off" - doesn't just affect the vapor canister on the car:

- Could result in your paying for gasoline that is fed back into the station’s tanks because your gas tank is already full. Gas stations pumps are equipped with vapor recovery systems that feeds back gas vapors into the their tanks to prevent gas vapors pollutant from escaping into the air. When your tank is full (pump shuts off due to pressure differential - vapors and even liquid gasoline is redirected to the station’s storage tanks)

- You've just used up the expansion room (extra space needed for gasoline expansion). This will cause gasoline vapors and liquid gasoline to have nowhere else to go except into your vehicle’s vapor collection system (this is how the vapor canister gets filled with gas)

- Also causes the fouling of the station’s vapor recovery system (they have a bigger version of your charcoal canister). Potentially causing excess vapors to excape the system and possibly cause the gas pump to fail to work properly for the next person.

Just the prospect of giving away more money at the pump and knowing how much gasoline expands - caused me to never top off.

[Bikeman982]

I have the problem of trying to cram too much gas into my tank at the fill-ups. I tend to top it off to the point where it starts to come out the filler neck. It usually runs down the body to the ground and at todays prices, that's wasted money. Doesn't always happen, just when I try to round off the dollar amount and accidently go over and then try for the next even amount.

[Anton]

Update:
After the work, 50% success. CEL back on, this time only one DTC. P0441, incorrect purge flow. I guess the P0446 was fixed by the new VSV.

I'm happy enough with these results, and I don't think I will be chaging the canniser any time soon. :ph34r:

Anton