Pressure in tank, fumes, explosions etc.

I have the same problem right now on a 1982 308GTSI Euro Spec, I have made the cap vent temporarily until I can find the problem , I have read all the posts here and copied the diagrams so hopefully with everyone"s help here I can locate the problem quickly.

I have just purchased this car it is my first Ferrari, the car has had extensive work done to it before I bought it and so far this is all that is wrong.

 

Welcome!

 

FWIW, my '75 GT4 is equiped with only the charcoal canister and the three-way valve and I have no pressure/vacuum problems with the gas tanks and very little fumes left in the garage after a drive. Those fumes come from the fuel evaporating out of the float bowls (I'm sure that's why they developed that trap-door system in later carb cars).

I know (at least, the last time I checked which was a while ago) that the charcoal canister was still available, but the three-way valve was NLA... I noticed that that three-way valve was nearly identical (in appearance in a photo, but size in real life?) to the one used in a U.S.-spec Lancia Beta.

The three-way valve allows pressure in the gas tanks to vent into the charcoal canister, allows ambient air in (via holes in the mounting flange) if there's a vacuum in the tanks and if an excess amount of pressure builds in the tanks, it'll vent that to atmosphere (which is the engine bay by-the-way...), bypassing the charcoal canister.
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I seemed to have the gasoline smell after a drive so I decided to overhaul the system. The first thing I did was to rebuild the carbon canister, replacing the charcoal with some stuff I got from an aquarium supply. There is a thread covering the rebuild on this panel. Lots of guys made fun of me, but I tell you that carbon needs to be replaced every 10 years because it becomes saturated and inefficient. The system works great if the vapor separater and the charcoal canister are in working order.

 

Resurrecting an old thread.
Last week after a long time in hot stop and go traffic I got a huge rush of hot air (and fumes) when I opened the gas cap. Sounds like what's being discussed here.
Are there any new thoughts on the problem?

77 GT/4

 

Dave, yours is stock. So you shouldnt have back pressure. Is this the first time this has happened since you moved to the old age home?

I'm in the same boat with a few that have altered their system.

 

Hi.
I assume that its stock. I haven't been able to get under the car since the incident to check things out.
Yes it's the first time. The situation was extreme. Long time idling in the heat (stayed dead cool, thank you Dave F.) and the tank was more than half empty.

BTW I was on my way back from your retirement home, M.I.

 

The other thing too is, were your tanks almost empty? Could that have done that too? A professional can chime in on that. Hopefully it doesn't happen again.

I didn't get a chance to go down Marco this winter. I couldn't bring myself to leave all the snow and cold we had.

 

Define almost empty.
Gauge said empty but more like 1/4 tank left. But that's another issue.

Good thing you didn't come down. You'd have never left. And then where'd you be?


My sympathies on the brutal winter.

 

Hose 29 appears to be a vent near the filler.