EVAP vent valve leaking fuel - Help!
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From: Lewisville TX
EVAP vent valve leaking fuel - Help!
Update! Cause found, see post #7
The EVAP vent valve, shown in the picture below, leaks fuel ONLY after a fill-up. I do not add fuel after first cut-off at pump. An additional symptom is that the the engine idle pulses up and down until I burn off a bit of gas. If I fill up and drive 10 miles or so, this doesn't happen.
Something somewhere has failed but I have not been able to determine what it is. I have spent several hours researcing this forum and the web in general.
Raw gas must be in the evap tank for fuel to get to this vent valve.
Oh, and there are no codes.
I'm stumped.....
Anyone have a clue what's causing this?
Any help would be appreciated.
The EVAP vent valve, shown in the picture below, leaks fuel ONLY after a fill-up. I do not add fuel after first cut-off at pump. An additional symptom is that the the engine idle pulses up and down until I burn off a bit of gas. If I fill up and drive 10 miles or so, this doesn't happen.
Something somewhere has failed but I have not been able to determine what it is. I have spent several hours researcing this forum and the web in general.
Raw gas must be in the evap tank for fuel to get to this vent valve.
Oh, and there are no codes.
I'm stumped.....
Anyone have a clue what's causing this?
Any help would be appreciated.
Last edited by TB04TJ; Mar 12, 2012 at 05:56 PM.
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From: Lewisville TX
Additional research points in this direction:
'The fill limiter vent valve (FLVV) (6)--this valve acts as a shut off valve. The FLVV is located on the top of the right fuel tank. This valve is not serviced separately.
The FLVV has the following functions:
Controls the fuel tank fill level by closing the primary vent from the fuel tank.
Prevents the fuel from exiting the fuel tank via the EVAP pipe to the canister.
Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from the fuel tank to the EVAP canister.
'
If the FLVV has failed fuel would enter the evap canister and therefore the vents and purge system causing fuel to leak from the vent and the idle problem if the purge valve was open.
Since the FLVV can't be serviced, sounds like a new fuel tank.
This must be a rare failure or I think I would have found a few post on this issue.
Of course, I'm not positive that this is the problem but after studying the C5 fuel system design for a few hours, this makes the most sense.
It would be great if there is an expert among you all to confirm my diagnosis.
'The fill limiter vent valve (FLVV) (6)--this valve acts as a shut off valve. The FLVV is located on the top of the right fuel tank. This valve is not serviced separately.
The FLVV has the following functions:
Controls the fuel tank fill level by closing the primary vent from the fuel tank.
Prevents the fuel from exiting the fuel tank via the EVAP pipe to the canister.
Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from the fuel tank to the EVAP canister.
'
If the FLVV has failed fuel would enter the evap canister and therefore the vents and purge system causing fuel to leak from the vent and the idle problem if the purge valve was open.
Since the FLVV can't be serviced, sounds like a new fuel tank.
This must be a rare failure or I think I would have found a few post on this issue.
Of course, I'm not positive that this is the problem but after studying the C5 fuel system design for a few hours, this makes the most sense.
It would be great if there is an expert among you all to confirm my diagnosis.
Last edited by TB04TJ; Feb 26, 2012 at 07:37 AM.
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From: Lewisville TX
The valve has been inspected and has no visible cracks.
The problem isn't so much that gas leaks out of it but more that liquid gasoline is getting to it at all. Everything from the FLVV downstream appears to be in place to work with gas vapors only, not liquid gasoline.
Since there has been only one reply, I'm guessing this must be a rare thing indeed.
I'll be replacing the right gas tank and I'll post the results in case someone else has this issue in the future.
Another Question:
Since I know that the evporator canister has been filled with liquid gasoline, it it now worthless? Just asking because the tank has to be removed to replace it.
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From: Capitol city CA
Have you replaced the tank yet? If so, did this solve your problem?
I just filled up my tank today and had gas leaking from this same area. I haven't confirmed exactly where it is leaking. I lost a fair amount at the gas station, but after driving home, not another drop has come out.
I had a CEL for the evap system a few days ago, reset it and it never came back, but then today I saw the leak.
Ben
I just filled up my tank today and had gas leaking from this same area. I haven't confirmed exactly where it is leaking. I lost a fair amount at the gas station, but after driving home, not another drop has come out.
I had a CEL for the evap system a few days ago, reset it and it never came back, but then today I saw the leak.
Ben
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From: Lewisville TX
Finally drained and removed the right fuel tank. I could hear something rolling around inside so I removed the level sensor and found this:
My guess is that this IS the FLVV. Looks like it unscrewed from the housing. If my hand was small enough I could probably put it back in place but there is no way my hand will fit through that opening.
My guess is that this IS the FLVV. Looks like it unscrewed from the housing. If my hand was small enough I could probably put it back in place but there is no way my hand will fit through that opening.
