EVAP Valves and the dreaded P0455 error

After owning my 2001 360 F1 Spider for a year and half I think I have encountered all the common problems. Some I knew about at the time of purchase some I did not. Shortly after getting my car home I got a CEL which my OBD said was P0455 Major EVAP leak. A call to the dealer yielded "oh yeah that's common when the gas cap is loose just tighten it up". CEL continued but at varying times...I could go hours some days with no light, minutes other days. A smoke test revealed the driverside tank was leaking. Dealer wanted $2500 to replace all four valves....stating it was common for them to break and once you have the top off you might as well replace all of them. Seems crazy to me for plastic parts which contain gasoline next to a motor to "commonly break" but it does happen.

My first attempt to fix this was a bandaide using 3M 5200 and a popisicle stick. Through the fuel pump access cover, under the top, I was able to smear enough goo over the cracked EVAP valve to prolong the CEL but it still happened. With the holiday week I took the bull by the horns and just pulled the top off and replaced the EVAP valve. About 4 hours in total labor but while I was in there I off course did other things so this project spread out over two weekends.

I found Volume 2 Section N "Convertible Top" was very valuable help from the Workshop Manual. It went back together like a piece of cake and no CEL after 100 miles and fill up. I only replaced the one valve to the tune of $350. I have read stories that early valves were green and prone to problems, newer valves are yellow, and I noticed European valves appear to be white. I have wondered what the real story is in the color coding but never figured it out. At any rate should you get a P0455 a smoke test is the best thing you can do to uncover this common problem.
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hope that I NEVER see that code. great thread for reference!

 

How difficult is it to reach those valves on the coupe? I would imagine that the hardest part of the job is to get the whole convertible top mechanism off, so the coupe should be a much easier repair? How do the valves come out of the tank?

I also just realized that according to your photos, and Ricambi's drawings, it appears that the spider has 4 valves and the coupe has 2. That is a $700 savings right there! Not bad. I hope that it is an easy enough repair, that if mine ever fail, I would be able to do the repair my self.

 

Verry hard man! Specially the passenger side.

 

No, not on a coupe, once the two side panels are off, the top of both fuel tanks are exposed. I had all four hoses replaced a few years ago. Each hose cost $250 USD then, no after market hoses out there.

I know as I replaced the fuel level sensor earlier. Thanks to Ray Johns write up.