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Ford 6.8L V10 Excessive Vapor Smell from Charcoal Canister

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.
-Replaced Fuel Cap (Genuine Ford)
-Visually inspected the Evap Lines - Look Good
-Visually inspected Fuel Line and Fuel Filter - Look Good
-Checked the Fuel System for Leaks - None
-Pressure Tested the Fuel System - No Leaks
-Ran Multiple Smoke Tests on Evap System - No Leaks
-Checked the Computer for Codes - No Codes
-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!

Was the carbon canister vent solenoid replaced with the canister? When you pull in with a low gas tank, immediately try daubing soapy water around all the evap tubes and connections you can see; you may get lucky.

Purge solenoid valve may be stuck open.

Thanks for the tip about the soapy water, insightful. I’ll give it a try. There’s no Canister Vent Solenoid with this model. It only came with California emissions. It’s just a simple cap… that costs $27.

Jesmed1, I was thinking about just going ahead and replacing the Purge Valve. My mechanic says that if it was busted there’d be a code, but I don’t think it would hurt to try.

Thanks for the feedback!

Since you live in California with emissions testing, you could have your mechanic take the emissions probe and sniff around the canister. The probe will sense the gas vapor as unburned hydrocarbon and should be able to pinpoint where the leak is.

Do you stop fueling when the gas nozzle shuts off at the pump? Most cases of raw gas in the charcoal canister comes from the owner overfilling the gas tank.

Hi Jesmed1, its not a CA truck and doesn’t have CA emissions. It did pass the emissions test here in AZ, though.

Hi Missileman, I make sure not to overfill the tank. 44 gallons is enough, and sometimes the pumps shut me off at $100.

Gasoline has vapor pressure…Some gasoline’s have more than others…The hotter it is, the higher the vapor pressure and the more likely the EVAP system will be overwhelmed. Next time your are at 1/2 tank or less, leave the gas-cap on intentionally loose and see what happens…Your CEL should come on and a EVAP code set…But maybe not…Worth a try…

@TheRedBeast01 … Yow! The last time I put 44 gallons in a vehicle it was in a large motorhome that I once owned with twin fuel tanks.

Caddyman, great suggestion! Here in AZ it’s about 105 degrees plus, so I will give that a shot.

And that’s right, missleman – 44 gallons. It takes a while to fill up.

I’ll assume your truck has a typical circulating fuel system where the fuel from the pressure regulator is returned to the tank. Look for places where the fuel supply or return line is near anything hot and insulate the line there. You cannot over-insulate these lines, especially in AZ. I’ve used Armaflex with good success:

Edit: Also use flat insulation on the fuel tank(s) if near an exhaust pipe. Permatex yellow weatherstrip adhesive works great for this.

Thanks insightful!

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.

Just curious, what is great mileage for what it is?

12 City and 15 Highway

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.

here is a picture.

Thanks knfenimore. 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!


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!

That is better mileage than my 72 Chevy Impala with a 350 got. It topped out at 12 highway- both before and after a tune up. My first, last and only Ghevy.