jvettman

The patient is a 2001, many mods including an H-pipe with cats deleted. I purchased the car only a few months ago and believe it or not, only filled it to full this last Saturday, previously I would only put like 10 gallons in it and move on. I noticed a heavy fuel smell when I got it home but nothing was dripping and nothing looked weird...just a bad smell which was not uncommon on this cammed cat deleted vette. Sunday I got up and my whole house smelled like gas so I knew I needed to do something. I hit the forums, read everything I could find on gas leaks, saw lots of leaking filters and thought I would start with that. I put the vett on jack stands and ramps, crawled underneath and didn't really see anything, touched things and nothing was wet, went back to the forums...and football.

Tonight I decided I needed to dig in because the car was still filling my house with fumes. I grabbed a filter on the way home just in case (why is this filter over $200 from GM?). I have some pics of what I found while poking around, I pulled both rear tires and both inner fenders. The strangest thing I saw was this:

Right exhaust just before the axle, that is the right tank strap just behind it.
What is that and why does it look like a weld?? It does not really matter, I am just curious...back to the fuel leak...

I got out an inspection camera and discovered the right tank was covered with wet fuel, even the strap/plate had leak indications all over it as illustrated by this pic:

Right tank strap bolts
I have no idea how I missed this on Sunday, but I was focusing on the drivers side because that seemed to be the highest smell concentration. I pulled the evap canister access panel and could see the top of the right tank and it was sprayed, there was wet fuel everywhere. I cant really tell where its coming from yet, the tanks were full of fuel and I needed to drain them down before I could pull the right tank. Here is what it looked like:

Upper right tank through evap canister access

I did read one forum post from 2011 in which someone had identified something with the evap canister lines that was leaking...the thread was not resolved so I don't know what that outcome was.
https://www.corvetteforum.com/forums...k-removal.html
I also found this post that talks about the evap valve built into the top of the tank that prevents leaking, shuts off the fuel when filling, and stops the tank from leaking in a rollover...its not a serviceable part
https://www.corvetteforum.com/forums...fuel-help.html

I believe that blue thing thats all wet in the last picture is the evap vent valve, I believe its broken and I am going to need a new tank, I also believe I don't do this for a living and would like some other opinions...what say you?

Thanks,
Jeff

Gunnmetalblue

Just got my evap vent valve replaced. Same symptoms as yours. Had a local shop do it for under $400.

jvettman

So...your saying it IS a replaceable part and I may not have to replace my tank?

Darkit

Wait...the evap vent solenoid that is under your hood?

jvettman

I believe the purge solenoid is, but there is another vent solenoid at the canister in front of the right rear wheel and there is another physical valve on the top of the right fuel tank. I believe my problem is with the vent valve on the tank. That valve has a float that closes the vent when the tank is full which results in the gas pump triping off because air pushes fuel back, it also closes in case the car inverts preventing leakage. I have read about the float valve breaking off which allows the tank to overfill and leak...which I believe it happening to me. I am open to being corrected on any of these beliefs, but as of right now I am planning to change the entire tank with a verified functional tank...its already on order from VetteVillains.

C5 Diag

Pictured is the PURGE VALVE/SOLENOID...where the blue connector is...vent valve is located R/H rear wheel well.

zachaeous

Here is a picture of a 2000-early 2003 passenger side fuel tank. I have the same issue with my 2001. I am going to have to remove the tank and see what is going on. Like the above post mine only shows signs of a leak when car is filled up and let sit in the garage.

Gunnmetalblue

Yes, it is a replaceable part. My mechanic ran a evap service test, showing less than .010 leakage (smoke test of the fuel tanks and crossover tube). He found the evap vent valve sealed properly but did not release. So he replaced it. This is what was causing the car to throw the P0172 and P0175 right and left bank rich codes and causing the strong fuel smell after filling up. He did not need to drop the tanks completely. Here is the part:
https://www.autopartswarehouse.com/sku/Chevrolet/Corvette/Standard/Vapor_Canister_Vent_Solenoid/2001/SICVS92.html?apwcid=bngpla&msclkid=61f11 602ba781dfbc5094da84e03fa50&utm_source=b ing&utm_medium=cpc&utm_campaign=APW-BNGPLA-Margin%2020%20to%2029%20percent&utm_term =1100010367661&utm_content=APW-BNGPLA-Margin%2020%20to%2029%20percent-Slow%20Mover%20Adgroup&gclid=CIGm_YfV190 CFW6HxQId3IcA1g&gclsrc=ds

jvettman

Good to know! Its not clear to me why this valve would cause fuel to come out of the top of my tank...but its really easy to change. I actually already took a picture of it by accident!

Crossover tube and vent solenoid

I think I will replace it for good measure.

jvettman

Got my new fuel tank in today, have not had time to swap it out yet, but here is a picture of the float valve inside the tank that prevents liquid fuel from entering the evap system:


Its hard to see in the pics, but its held in place with a small turn clamp:


The float is inside:



So, if this valve fails (people have found the floats rolling around inside the tank) the tank will be overfilled on a full fillup because the station pump is not shut off in time. Once its overfilled, the liquid fuel goes into the evap canister until its so full that it runs out the vent control valve. It also leaks out the top of the tank where the valve is located until the fuel is brought down to a level below the valve.

I have seen a number of posts that state there is fuel coming out of the vent valve...if you have liquid fuel at your vent valve, you have a problem with this float, not the vent valve.

Jeff