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Fuel Odor 91 Legacy/ Evaporative Canister
Posted 28 July 2003 - 02:46 PM
Per the service manual, I checked the evaporation line to the canister by unplugging it from the canister and verifying that it is unobstructed by blowing air through it. Also disconnected the purge hose and verified that the purge control solenoid valve will not pass air.
There is a third hose on the canister that is not shown in the service manual--it comes from the bottom of the canister and appears to be an overflow hose in case the canister becomes saturated. I'm pretty sure the fuel smell is originating from this hose.
Would replacing the canister help? Do they "wear out" over time? I'm assuming the purge control solenoid valve is Ok since it does not pass air and I'm getting no check engine light.
Thanks for any inputs,
Posted 28 July 2003 - 09:51 PM
One temporary help is to vent your gas tank (open the gas cap for just a couple of seconds).
Don't overfill the tank. Run about 3/4 full unless you're on a road trip.
Heck, one day when it was about 100F here, mine even was doing it with about half a tank! <img src=http://www.ezboard.com/intl/aenglish/images/emoticons/grin.gif ALT=" >D">
Posted 29 July 2003 - 12:29 AM
I think the only way to get rid of it is to replace ALL the hoses and the canister. The hoses age and start to develop tiny cracks that petrol molecules can pass through, and surely the carbon element in the canister has a limited life.
Worth the cost?? I don't think so. The human nose isn't all that insensitive and even tiny amounts of fuel in the air will register as smell.
However, I would not be happy with a fuel smell in the cabin. Perhaps you could get away with replacing the hoses in the engine compartment?
Oh, and heaven forbid: You MIGHT have a tiny hole in the fuel tank. Friend of mine has a Mercedes and we had to replace his fuel tank because of similar symptoms. The hole wasn't visible, but the leak left a dark patch on the outside of the tank and the cabin stank when on the move with the windows down!
But hey, Legacies have a protective plastic cover on the leading edge of the tank, so this is unlikely.
Posted 29 July 2003 - 06:48 PM
The purge valve is supposed to open when the engine is at operating temperature and running at faster than idle. The engine vacuum will draw the accumulated vapours out of the canister, to be burned by the engine. This assumes that the hose on the other side of the valve is properly connected to the intake manifold.
If the purge valve is stuck closed, the engine computer can't diagnose the problem. If it's stuck open, the engine won't idle properly.
Posted 29 July 2003 - 10:18 PM
Thanks very much for your inputs.
I will check the purge valve, Gerry, and post back with the results (and if defective, verify whether replacing the valve solves the odor problem).
Posted 01 August 2003 - 09:56 PM
Checked the purge solenoid valve by hooking a vacuum gage to the line when the engine was warm. It's drawing vacuum of about 4 in Hg at 4000 revs and I figured this was plenty to pull fresh air thru the canister.
Went ahead and replaced the canister today. Will post back after some hot days to note if this actually solved the problem. Stay tuned.
Posted 01 August 2003 - 10:15 PM
Posted 04 August 2003 - 08:46 AM
Think the activated carbon in the canister eventually becomes saturated. In other words, it stores the hydrocarbons and then releases them as fresh air is drawn across the carbon when the purge valve is open. But it likely always retains just a bit of hydrocarbon each time, and eventually becomes saturated.
Maybe I was lucky and didn't have the minute fuel leaks from old fuel hoses. I didn't go with the "loosen the fuel cap" approach because I was getting fuel odor in the cabin even when stopped at a stop light.
Thanks again for all the inputs.
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