Stall after fill-up: required to replace charcoal can due to overfilling?

Hi all,

When I left the house for work this morning, I decided to fill up my 2004 Tacoma 2.7L double cab, ~130k miles. There's a filling station right next to my workplace.

Immediately after refilling, I had a problem starting: it stalled almost immediately upon start. I tried a few times and same thing. No CEL either.

Finally after waiting a few minutes, I pumped the accelerator a few times and it started but had a rough/low idle. I had to do something as I was blocking customers from getting into the filling station. I limped over to the employee parking area next door, keeping my foot on the gas to prevent it from dying again.

After about an hour, I took a break, went back to my car and tried to see if it would start again. It did. It was like there was never a problem 1 hour before...

As I researched the problem, I suspect the charcoal canister likely has been super-saturated with fuel. Because, for the past several months (since summer), I have been "topping up" with every fill. (Not sure why I did that, probably to try to squeeze out as much time between fill-ups. ) Now, I'm not 100% sure that is the cause/if the charcoal canister is the issue but I greatly suspect it is. No other problems with the truck.

I was thinking about replacing it but then I found out it's kind of a PITA as I am a DIY guy and don't have the $ to have the dealer do it. So I started wondering:

• Does the charcoal canister become ruined once it has been saturated with fuel? Can it not "dry out" (for lack of a better phrase)?
• If I decide not to replace it, will the truck fail to maintain idle upon post-fill startup, even without topping off ("I'll never top off again!"), going forward?
• Can the truck ever stall during driving with a bad charcoal canister?
• Will other damage occur to the car/engine if I don't replace it?
• If no CEL came on, does that mean maybe it's not the charcoal canister? (IOW, wouldn't a bad charcoal canister throw a code?)

I also thought I read that there was charcoal canister valve, too. Could this have been damaged, too?

Thanks,
Paul

 

I'm a habitual topper offer. Interested in seeing the answers to your questions.

Do 3rd gens have this Charcoal Canister also?

 

To be clear how much I was topping-off, I was (ignorantly) going past the typical "couple of clicks"...

 

If it started again and ran ok, it probably burned up most of what was in the can as there is a vacuum line that runs to the intake that is either activated by the VSV (ecu) or when you are on part throttle.
If it started again, which it did, then you are probably ok if you stop topping it off now and give the can a chance to recover from driving around.

What you don't want is the one time you do top it off, it fills the can, and enough raw gas gets sucked into the intake to hydrolock the engine which could bend/throw a rod when you go to crank it.
Not to mention everytime you do that and start the vehicle you wash down the cylinder walls with raw gas, which means no lubrication until the next cycle assuming it doesn't hydrolock.
Also, over time the gas will get into the oil, and that will reduce your lubrication. If you were to do an oil analysis since you started topping off, you would likely see not so good results.

And just because it starts sometimes without issue, doesn't mean that it isn't sucking in some fuel from the canister, you are just sucking in an amount of fuel to where the engine can still combust the rich mixture.
The fact that you couldn't get it to start, means alot of gas and no lubrication, then you floored it to move it forward = poor engine.

Really, topping off is about the worst idea ever unless you don't care about your engine.
Most of that extra gas goes right into the can and gets sucked through the engine on startup (if you are lucky).
So you really aren't getting much more miles out of the tank, and is more or less a waste of gas.

If you have a problem with range, get another tank installed or carrying canisters like everyone else would be much better.

And Longview, most toyota's have the charcoal canister since the 80's. Some are in the engine bay, and in the more recent models toyota started putting them next to/on top of the gas tanks instead or in various other places (fender etc..). I do not know where it is on a 2nd or 3rd gen, but you do have one, and it is usually at a height above the top of the gas tank (even if its in the engine bay etc..).

They are meant to catch the vapors so think of it as a vent coming off the top of your gas tank, so that means to get gas in it you literally filled the gas tank to the very top plus some. If the canister is full of fuel along with the gas tank, this also leaves no room in the gas tank for the gas to evaporate on a hot day (which it does alot, if you have ever had a classic car without a fuel canister that vents to the atmosphere you would be able to smell it on a hot day in the garage, which is why I don't let my '71 vette sit in direct sunlight in the garage), and can create a potentially dangerous situation because by topping off you have basically plugged the only vent.

To be extra clear, there are old cars with no canister and just a vent to the air (smelly and pollutes), and there are newer cars with a canister that vents to the canister and then to the engine (not smelly and less polution).
There are no cars that would have a gas tank without a vent for safety reasons, and there would be no scenario where it would be ok to not have some type of vent, or fill your only vent up full of gas.
I hope that makes sense and everyone stops topping off for safety reasons at the very least.

 

Here is a way to check, remove the thing, hold it upside down. If fuel pours out, replace it. If you live in an emissions test state, just replace it as it will fail the sniffer.

All vehicles built from about 07 but definitely from 10 on are CA emissions compliant.

a CEL light may not come on in the earlier years due to no sensor being used in the canister. These days they have a solenoid or sensor that trips the Emissions malfunction side of the ECU. Can be expensive. I have heard of people being able to dry it out and have it work...never seen it done or met anyone who has done it... since charcoal melts away in gasoline, I done believe it can work.

 

Thanks for the replies. More questions:

Damn. If engine started and ran, am I out of the woods here? Meaning, if I threw a rod, engine would stop, correct?

If lubrication was affected, is the engine a lost cause at this point? If I replace the can and change out the oil, it seems engine damage due to this will be minimized?

 

Thank you for that tip.

Makes sense. I will try to replace it in the next week or so. Hope I haven't done too much other damage. Do you think I would be inflicting more damage if I drive around for the next week until I get it replaced?

 

it may stall out from vapor lock as this is a recirculated type device, a small amount of fuel is ok, what this stupid thing does is pull vapor from the tank and then that is sucked out by the engine, since it runs directly to the intake manifold any extra liquid floods the cylinders. If memory serves, you can find the canister to engine line, pull it, cap the nipple and things will be good, unless you have an electronic plug in the canister, if so... then no, not good to drive like this.

 

Fazeka, it is hard to say if the canister will be doing its job 100% now, but I wouldn't be so quick to replace it cause it is a pain to do so and might be fine.
Most of the time the canister can survive quite a few accidental overfills, until it gets completely saturated and sits for a long time.
I would guess alot of the time you are getting most of it sucked out through the engine right after you put it in there, but some might stay in the canister.

If it was my car, I would drive it regularly and do a couple more fill ups without topping off, stop it at 3/4 way if you can.
This will stop it from filling up more, and give it a chance to clear out any remaining liquid gas that might be in the canister.

If you do that and everything is fine going forward, you probably don't have to replace the canister.
If in the future when filling gas, it stops filling like half way through, and you have to keep on starting it again and again, you might have ruined the canister.
If you get a check engine light related to the canister later, you may have also ruined the canister.

That being said, it is a canister designed to hold fuel vapors and some amount of liquid fuel will likely be present, so it takes a lot to ruin it.
As long as it is not plugged and you are not topping it off, it shouldn't be dangerous to run it like that and see if it clears up.

As for the engine, you wouldn't have done any extensive damage in that period of time, but it all adds up over time.
I wouldn't worry about it if you stop now, but do realize that over time you will wipe out various bearings alot quicker which could eventually lead to needing a rebuild.

All I would do now in your case is change the oil when you get a chance, stop topping it off, and for a few fills go to just 3/4 to let the can recover if it still can.

And also, don't listen to Gixxers advice above, if you cap the line from the canister to the engine, you are essentially blocking off the only vent the canister has and thus the only vent the gas tank has which = bad.
The canister has a built in saftey valve in the case of being overpressurized it will vent straight to air in an emergency, and if you plug the line to the intake at various times when the pressure builds up enough it will trip the saftey valve and you will smell it outside the car or if your a/c is on fresh air, and this is not good because it means the pressure in your gas tank got to an unsafe level, and will do that over and over again when the vents are plugged = really bad.

 

I imagine they do since it's a key component of modern day emissions equipment. I used to top off habitually as well but stopped abruptly when I learned about the damage it can cause, that repair isn't exactly cheap (not crazy either). Probably depends on the vehicle and if you do it yourself or not.

I was filling up the other day and I swear in the entire time it took me to fill my tank, the lady next to me was topping hers off...probably for a solid 3 or 4 minutes straight. I wanted to say something but figured she'd probably think I was crazy or trying to mess with her.

Honestly I didn't have anything negative happen to my last car that I did it with, but I also only had it a few years.

 

If you remove the line from the engine the canister still vents to atmosphere. You miss read or mis interpreted.

my advise is sound AND part of diagnostic routine on pre electronic gizmo everything cars. The canister does not need engine vac to vent, which is why vapor lock can occur with a filled canister.

 

I see what you are saying now but you wrote cap the nipple, there is one on the intake and one on the canister. capping the one on the canister is very bad.
capping the one on the intake and leaving the one on the canister open is not a great idea when you have a canister potentially filled with gas.
At the very least, you would want a new line on the canister nipple running to the ground, in case of fuel vapors spraying or actual liquid fuel.
Also, I usually stick a clear fuel filter in that line just to keep an eye on it, but that is usually a work around for turbocharged vehicles or heavily modified vehicles.
That isn't for regular cars and it will not help get gas remnants out of the canister for the OP, without it being connected to the intake. It really doesn't test much either since the engine is running right now.
If the engine wasn't running I would disconnect it temporarily as you mentioned, being fully aware that the canister might push out fuel during operation (important and why you would want a line on it going to the ground).

 

disconnecting from the engine allows for vapors to naturally vent, which enables the engine to run as it should. In testing you can see changes in running if the canister has fuel in it, the rpm and fuel trims change. If you’re not a rush type TECH and a mechanic who looks for any way to get the most out of what is given ( or an ass for a customer)

then leaks or funky vapors are an enemy.

the vehicle does not need this crap to run and actually runs better without it.

it is a 100% California emissions part which is unfortunately forced on everyone now.

 

Not sure if it's been mentioned, but I've been told that if the charcoal pellets get soaked with gas, they are ruined and won't work properly after.

 

First, stop topping up. second, RELAX your cannister or engine are not doomed and you will not be flooding cylinders with raw gas. You may get a CEL as you do have a EVAP purge selnoid which will throw P0441 or P0446 if the cannister flow gets hinkey for over 2 drive cycles. The purge selnoid is a $80 Toyota part easily accesible under hood driver side top of wheel well. If you loose sleep over this just change your oil.

 

that is true if they are soaked. FERD had an issue in the late 90’s with carbon pellets coming apart in to a particulate dust that clogged up the system, result was a very expensive replacement of the entire evap system. It was a common issue that happened with or without fuel in the canister, fuel in the canister caused a rapid decay.

KIA had a similar issue on the optima where the canister got filled and the car would only allow a real slow fill and never to a full tank.
The canister was/is about 800 bills. There was a huge testing procedure first, solenoid, smoke test, disconnect and disable, attempt a fill up, if the car would still refuse to properly fill then the fuel tank had to come out and the check valve examined and 9 out of ten times, new fuel tank as the valve was a “non serviceable” item.

do not top off is the fix. I wait for the pump to click off, count to ten and pull the trigger again, that’s it. 10 seconds gives the fuel enough time to stop sloshing around so much and allows for about .1-.25 of a gallon to be safely added.

Then again WTF do I know.

 

I think we are talking about the same stuff more or less so no worries but I wouldn't recommend anyone who doesn't know the evap system well to mess with it at all.
I think we can all agree at least OP needs to stop topping off and drive the car normally and see how it reacts from there. And optionally change the oil soon if it smells gassy (check the dip stick).

If it acts up more after a few fills then look into replacement.

 

Thanks again guys. Plan of attack: Drain/replace oil ASAP (necessary to change oil filter? I change every 6 months, just did 3 months ago). Not top off on gas anymore. Observe. On next fill, will be curious on start up after fill up. Will continue to observe on for next couple of tankfuls.

Anyway to monitor oil to determine if it's getting diluted with gas? When I checked the dipstick today, I couldn't see anything in the oil that indicated it was different than normal. Also didn't smell any gas.

 

Usually manufacturers incorporate a way to clear a flooded engine. This is accomplished by doing the following. With the key off, push and hold the accelerator pedal to the floor and crank it over. If yours is equipped, this shuts off the grounding signal to the fuel injectors. Be prepared... if this isn't incorporated, back off the full throttle immediately, duh...

 

Fazeka from what you are saying you should be fine for the most part. You can smell the gas on the dipstick if its bad, I know its odd most people don't usually smell their dipstick but when you have old classic cars it's something you do from time to time. If it doesn't smell a little like gas you are probably ok. some people wave a lighter underneath the end of the dipstick and look for little spark ups. You should be ok though it sounds like if you can't smell it just run it till the next oil change and do the oil and filter.