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I believe this picture is a good representation of how it works.

http://engine-codes.com/uploads/images/3059.gif

When fueling, the gasses go through the canister and out the open vent. As the gasses pass through, the charcoal absorbs some of the HCs. When the car is running, the engine pulls a vacuum, drawing outside air through the canister. The hydrocarbons are released and get burned in the engine. My guess is that charcoal particles make it into the valve, eventually clogging it. I had an old dodge pick up with a slant six where I had to occasionally take apart the 1 bbl carb and clean out the charcoal that got sucked in from the canister which was under the hood.

I see the valve mounted on the end of the canister. Can someone explain how I can release the clips to remove it without breaking them? Looks like that is an issue.
 

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The service manual emphasizes several times that it is very easy to break the vent solenoid.

That pic and description are overly simplified, the operation as described would be a running vacuum leak.

Now after looking I'm even getting confused, the ORVR diagrams I'm finding show the canister VENT solenoid as normally open and why do you need a solenoid if the thing stays open?? Easier to be an emission leak that way too. Also, the ORVR diagram shown in the '02 Focus wagon service manual clearly shows pieces of equipment in the ORVR system that my car does not have. It does not show the filler vent pipe either.

'...charcoal absorbs some of the HCs.'

It better be absorbing a lot more than just 'some'. They failed cars here for 20 PPM and so small an amount as to be zero.
 

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I believe this picture is a good representation of how it works.
http://engine-codes.com/uploads/images/3059.gif
That pic and description are overly simplified,...
Overly simplified, yes. Plus very misleading because it shows air-flow Arrows going in a direction that is impossible during refuel because the Purge valve is Closed during refuel.


When fueling, the gasses go through the canister and out the open vent.
Yes sir. I have found nothing to prove otherwise.

... the operation as described would be a running vacuum leak.
No it is not, but it will become a controlled & calculated vac leak when the PCM commands the purge valve to open.

Also, on a similar note, the PCM commands the Canister Vent Solenoid to close during; "seals the EVAP system for the Inspection and Maintenance (I/M 240) test and OBDII leak and pressure tests."

"OBDII leak and pressure tests" are the automatic tests being done by the PCM for Evap Monitor and ditto for PCM checking for evap gross leaks.

As previously stated/guessed, I believe my PZEV has additional controls that would prevent the canister from breathing-to-atmosphere when parked. Also, remember that there other control valves discussed little or not at all during this thread. Ref pic I posted on page-2. I might later go see if I can find a functional diagram and a How-Does-It-Work on the Focus PZEV system.


... the ORVR diagrams I'm finding show the canister VENT solenoid as normally open and why do you need a solenoid if the thing stays open??
It does not always stay Open. It is Closed by the PCM for two or more reasons. See comments above.
 

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What's the second reason?

'No it is not...'

My response there was in relation to the operation there too simply described as both ends open with no control there, THAT would be a vacuum leak.....

Crow eating time for me.

Ever since they have put electrical solenoid valves on the canister itself I have assumed they had to be closed and that is WRONG. I wondered if they were open then just WHY did they add the solenoid as it then does nothing??? That all was based on a further assumption (mistake) that the PCM evap system leak test was based on pressure and now I've found it is based on VACUUM which changes everything. The solenoid would then be normally open instead of closed. It only gets closed when PCM commands it for system leak testing, and open the rest of the time.

http://www.alldatadiy.com/alldatadiy/DIY~G~C41407~R0~OD~N/0/80851247/83204708/83204719/110671822/34853741/34857029/34858641/34850997/42095775/121016236

Look below the first pic to the 'evap canister purge valve no flow test' and the procedure there. That is a VACUUM test...........the PCM also does it on the fly.

My bad and I apologize to all, and thanks to Marde for pushing me far enough to dig further on the subject. My understanding expanded as well.

Still, I view most of the vapor at gas fillup as traveling up that vent pipe rather than going through the canister, the vent has less resistance than canister and much of the vapor is made while sluicing down the filler tube. As long as the bottom of tube door is emitting fuel into the tank it will be emitting vapors out as well, the pressure differential there. Like said before you can visibly see the vapor pouring out of the filler area and onto the ground, getting rid of the gas station vacuum requirement actually will be increasing HC emissions unless the newer systems actually becomes so good they can pass air through canister as fast as that vent pipe. They should be DROPPING the vent pipe on later models and making the filler tube fit the gas pump nozzle tighter, that will stop that and force ALL vapors to go to the canister. Sounds like they are going in that direction...........
 

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"Going in that direction" could show another reason for the capless fill system on the MkIII version, with tight fit to the nozzle. That one DOES have a vent to ground between the outside of the cap & the inner seal, proven when it drips with top up attempts. A way to prevent liquid fuel coming out the fill hole when that happens.
 

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What's the second reason?
...
The answer was in my last post. The reason for the quote-marks (below) is that I quoted another source. The words came from ALLDATAdiy.com.
...the PCM commands the Canister Vent Solenoid to close during; "seals the EVAP system for the Inspection and Maintenance (I/M 240) test and OBDII leak and pressure tests."

... the PCM evap system leak test was based on pressure and now I've found it is based on VACUUM which changes everything....
Not sure why that changes everything... pretty sure I read the system uses pressure and vacuum for the different types of on-board testing.

... Like said before you can visibly see the vapor pouring out of the filler area and onto the ground, getting rid of the gas station vacuum requirement actually will be increasing HC emissions unless the newer systems actually becomes so good they can pass air through canister as fast as that vent pipe. They should be DROPPING the vent pipe on later models and making the filler tube fit the gas pump nozzle tighter, that will stop that and force ALL vapors to go to the canister. Sounds like they are going in that direction...........
I can not remember seeing a significant amount of seeping vapors from the filler neck since... many many years ago. Not sure you can either; especially since you have the VRS filling stations in your area. You should go back and watch that video again, the link you posted. I watched it a second time (yesterday) and it covers and answers a lot of what we are re-hashing here. ORVR does exactly what you just said, they designed the system with the filler tube smaller than older non-ORVR cars had. Furthermore, the quote at post-17 from the EPA document loosely says ORVR does a great job and VRS is un-necessary and/or redundant and is even a "dis-benefit" is some cases. You said "Sounds like they are going in that direction" but we already have. Only thing remaining to do is; getting those people with clear memories of 1970 vapors hitting the ground during re-fuel to realize where we are at today; and to see what is really happening with ORVR equipped vehicles.

Seems like ORVR handles most/all refuel vapors very well and is only stressed or maxed out during diurnal (siiting) periods.
 

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Gonna check that pretty quick......................don't think it has been many years ago but I cannot say when other than that. When in doubt, test, and test again.............hitting 92 or 93 this w/e in temps.

The system does have to hold pressure but I assumed the test was for not for such since looking here lately I have found nothing that says a specific test for it. May have just not tripped over it though. What I have found validates the vacuum idea and I always as well wondered about the pressure test as in, if the PCM wants to do one, just how does it artificially raise the pressure in the tank? I always had an issue with that before, just didn't pursue it out. Stupid me never thought about how easy it is to raise vacuum, simply close off system and let the fuel pump do it.

On an aside, made a smoke machine for the inevitable day, worked fine but the oil worked its' way into the heating element to burn and short it out, mods for that coming up.
 

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I suddenly developed the gas fill prob with no check engine light. Crawled underneath and pulled the vent hose off the vent valve and was able to blow through it. Took the vent valve off and was able to blow through it. Then I tried to blow into the canister and couldn't. Disconnected the tank hose from the canister. Took the three nuts off(one of the bolts broke off) and pried the damn thing out. Following the path of a Ranger owner HERE, I took apart the bigger of the two cans and found the clumped up 'moldy' pellets. Now I have to seal it up and reinstall.
 

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I'm having problems putting gas in 03 focus. Doesn't seem to be any restrictions in vent line. Is there a screen in filler tube that may get clogged?
 

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No.

Try putting nozzle in in another orientation, like 90 degrees. I have one Focus that fills in any position, the other is picky about it, I turn the nozzle to 90 and it fills like lightning then.

Just the amount the nozzle puts out at 100% open can make it do it, some flow too much and if you hit the tube wall to stack it up then you WILL have issues. Play with how the gas flows out of the nozzle to hit the filler inside wall, often you can find a better aim that lets the fuel hug that wall better to not shut the pump off.
 

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Just fixed my slow fill on my 05 zx3. Dropped the rear axle assembly, dropped the fuel tank just low enough to remove the carbon filter assembly then jacked the tank back up and secured the tank. Marked the large carbon cannister then cut the top off with a box cutter at the recessed seam. Measured from top of the cannister to the top of the carbon pellets. Dumped the white encrusted pellets and cleaned all the filters. Filled the cannister with the pellet style activated charcoal from the local fish aquarium supply cost about 15.00. Glued the top back on with 2 part plastic epoxy and clamped until
the next day. Then cleaned the small cannister with water. Let dry overnight then reinstalled. Total cost about 25.00.
 

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The fuel tanks vent right at the filler neck, there is a separate tube running right next to the big one..........and yes I was rebuilding carbon canisters like that 30 years ago. You can actually reuse the charcoal that came out too by burning it then rinsing it off then heating to reactivate it.

That charcoal seems awful expensive, I was used to getting it for way less than that but it's been awhile.
 

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At the MG Experience website that I subscribe to John Twist has a video on rebuilding the carbon canisters and he shows heating the carbon but I am hesitant to because of heat with fuel. For around 15.00 it gives me a piece of mind.The cost of a carbon canister assembly is around 250.00 the DYI guys can save some money. I was surprised to see the white brick that came out of the can when I emptied it.
 

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Same as starting up a charcoal pile on a bar-b-que grill.......................you do it away from the house or other of course. Stop short of lighting the charcoal off, just burn the vapor off it. In fact, that charcoal will work too if busted up with a hammer and the dust strained off it.
 

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Just did this. What a pain. Must lift the body off the subframe, 6 bolts and the shock bolts as well, and take the tank down too (at least on my model, 2007 SES ZX3 MTX). Check the vent solenod. It should be open unless 12 volts applied to it. It should fully close, if it does not it can cause mixture issues in the intake, long crank times before start, occasional misses, and then it contributes to the horrible click-offs at the pump.

I removed the canister and, using a paint scraper and a hammer I popped the flat plate off the end flange, revealing a strange capsule end, like the shell end of a pressure vessel, held on by a metal clip that was clipped on a protruding center post. I removed the clip using a small strong screwdriver to bend the tangs on it. With the clip off, I could pull the shell and dump out the charcoal pellets. About the size of donut sprinkles, smaller than I thought, but about 1-1/2 liters by my guess. I found that there was about a cup or two that had bonded together and crusted together, degrading into white powder near one of the hose connections, so I tapped the housing until it all fell out, along with the filters.

I cleaned the filters and rinsed the new aquarium charcoal pellets (about 3x the size pellets) then slid the filters back down into the top of the case and refilled the case adding a few cups of the old pellets since they were in good shape. I put the end shell back on with the clip, I probably should have silicone sealed it but it sealed up well when I epoxied the end cover plate and weighted it with a brake rotor all day and that sealed it up just fine.

Before I cleared the clog it was barely able to pass any air when blowing through it. Maybe 10%. After the rebuild it blows easily.

So with the new vent solenoid and this new canister it starts easily and I gassed it today, it took 12 gallons without a click-off at full stream - perfect. Not bad for $50 in materials and the valve from RockAuto.com. However, if I had to do it all over again, I would take it to a good mechanic and pay the $300 my daughter paid to fix hers. I've done major work on cars more often than I care to, including a clutch in my 95 SHO, and the head rebuild on my 91XR2, and this was almost right up there in the misery factor. Messy, and just about everything that could go wrong did go wrong except the spilled gallon of gas on the floor ignighting.. Or i'd be writing this from the ICU.
 

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dreaded cant fill gas tank problem

I’m new here, so please forgive my ignorance.I’ve found that I can get a pretty good amount of gas in the tank of my 2005 Focus (270,000+ miles) by using a long nosed funnel and a 5 gallon plastic gas can — haven’t tried the funnel with a filling station hose, but will, very slowly.

My question: is this safe? Someone posted: “Apears [sic] the The Charcoal Canister/EVAP is the problem.”

I don’t have the faintest idea what the Charcoal Canister/EVAP does, but is it safe to bypass it with long-nose funnel or tubing?

Thanks

bartbrown
 

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I’m new here, so please forgive my ignorance.I’ve found that I can get a pretty good amount of gas in the tank of my 2005 Focus (270,000+ miles) by using a long nosed funnel and a 5 gallon plastic gas can — haven’t tried the funnel with a filling station hose, but will, very slowly.

My question: is this safe? Someone posted: “Apears [sic] the The Charcoal Canister/EVAP is the problem.”

I don’t have the faintest idea what the Charcoal Canister/EVAP does, but is it safe to bypass it with long-nose funnel or tubing?

Thanks

bartbrown
Bartbrown,
The EVAP (evaporative emissions) system controls fuel 'vapors' from the fuel tank and fuel system of the vehicle so that they are not released into the atmosphere. When you fill any vessel with liquid you must allow for a way for the air in the vessel to escape. The EVAP system controls the amount of air that is allowed in/out of the fuel tank and if it has failed that can cause the filling difficulties discussed here. Your vehicle's issue may/may not be EVAP related. Bypassing/disabling any mandated emissions system - like EVAP - is generally illegal.

Paul
 

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Is the purge solenoid supposed to be open when the vehicle is off? I have a new Ford solenoid in hand, and it's closed with no power applied.
 
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