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6.8L V10 Excessive Vapor from Charcoal Canister Under Hood


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I’ve got an issue that both my mechanic and I can’t figure out. I have a 2001 Ford Excursion 6.8L V10. It runs like a champ, gets really good mileage for what it is, but there a strong fuel vapor smell coming from the charcoal vapor canister under the hood. You can smell it outside the truck and the smell gets pulled in through the vents - have to use Max AC recirc.


After checking and testing, I can confirm that the fuel vapor smell is coming from the charcoal canister and not anywhere else on the engine. The smell gets worse as the tank drains: Full Tank - Almost No Smell; Half Tank - Strong Smell; 1/4 Tank - Very Strong Smell.


Here is all that we have tried.

  1. Replaced Fuel Cap (Genuine Ford)
  2. Visually inspected the Evap Lines - Look Good
  3. Visually inspected Fuel Line and Fuel Filter - Look Good
  4. Checked the Fuel System for Leaks - None
  5. Pressure Tested the Fuel System - No Leaks
  6. Ran Multiple Smoke Tests on Evap System - No Leaks
  7. Checked the Computer for Codes - No Codes
  8. Replaced the Charcoal Vapor Canister (Genuine Ford)

We are totally stumped. I searched all the forums and can find issues with plugs, fuel injector o-rings, and leaks, but this has all be checked.


Any help would be appreciated!

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Sounds like the fuel tank is building pressure and the evap system cannot handle it. Even though there are no codes, the evap system is malfunctioning. First, is this a green state/California emission vehicle? I am assuming it isn't, but if it is, the diagnostics change. IS the canister vent valve (electrical valve between canister and engine) functioning normally, lines intact and not plugged there? Is the fuel tank venting system allowing it to vent?

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Thanks for the feedback YT90SC. This truck does not have CA emissions, so there is no Vapor Canister Vent Solenoid. I do think that the Canister Purge Valve may be the culprit and I have been tempted to swap it out, but my mechanic swears that it would throw a code. I don't think it would hurt to swap in a new one. It's easy enough to do.

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Being NON green state emissions and OVER 8500, it probably won't set a code for evap issues. Its too dumb a system. If I remember right, I dont think it has any real way to monitor true flow. IT does not have a Fuel Tank Pressure (FTP) sensor and I dont think they used a purge flow (PF) sensor either. So that is just left with the circuit monitor for the solenoid. Blocked, kinked or otherwise it can't tell if the flow is there when commanded. Without a code being set, I would imagine its ok electrically, just mechanically amiss. Be sure that the vac line is open as well, especially where it connects to engine vaccuum. They love to get mushy and suck shut when running, but look ok engine off.

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I swapped in a new Vapor Canister Purge Valve today. Only ran about 30 miles so far in mixed driving. The odor from the Vapor Canister has been greatly reduced, but is not all the way gone yet -- but better. I'll need to put some more miles on it to have all of the built up fumes cycle out.

Right now I'm at about 1/4 tank.

I will post updates.
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I think I may have found the problem. After driving about 100 miles yesterday with the new Vapor Canister Purge Valve, there was really no difference. I compared the old part to the new and noticed that the Input Port Vacuum (To Intake Manifold) on the old part was broken off completely.


The Input Port Vacuum on the Vapor Canister Purge Valve sticks out the bottom and is extremely small. I checked to see if I could find any loose and unused lines, but none.


Where does this line connect into the intake? Does anyone have a part number or size?


If I know where it goes, I can pick up a hose to install. I couldn't find any open ports in the back of the intake.

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Found it!

There was a handy dandy diagram on the hood of the truck over my head the whole time. It took a while to trace it, but I found a very small red vacuum line and it had the broken nipple from the old Purge Valve in it. I attached it to the new and will see how it goes!

I think this will do it!

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Found and fixed the problem! Thank you to everyone on the forum for the suggestions and help. Here is what it was:


The Vacuum Input Port on the old Vapor Canister Purge Valve somehow got sheared off. It was broken so clean you couldn't even tell that there was a nipple for the vacuum line on the old part. When I installed the new Vapor Canister Purge Valve I noticed the extra port, which was the Vacuum Input Port, but no hose to go with it.


I found a diagram on the hood of the truck that showed where the hose should have been. I dug and found it buried near the fuel rail. It still had the broken plastic from the old Purge Valve. It's a very small red vacuum line. I plugged it back in and ran the truck. The smell is gone! Vapor Canister is purging and all is well!

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