| Author |
Message |
'75 308 GT4 (Peter)
| | Posted on Monday, April 23, 2001 - 7:56 pm: | |
I'm surprised heat build-up is causing the pressure increase, that wrinkle coating is an insulator! After removing the gas tanks from my car, I brought them to work and had them steam cleaned to prevent any explosion while they were to sit in my garage. Our steamers produce about 200°F at the end of the hose. While steaming, I laid my bare hand on the side of the tank and it felt mildly warm. On a bare aluminum barb on the tank, I touched it and scalded my finger! So that insulation is there for a reason, it does get incredibly hot in that engine bay!
What could be the reason that heat is getting through, is that insulation doesn't stick to the tank for s---. It was flaking off in my hand. I used a polyurethane sealant to seal/glue it back and will be painting the tanks with a high-temp engine enamel.
You're right, gas tank vapours are vented through a carbon canister, but if I remember correctly from the P.C., the Euro car doesn't have one (maybe that version uses a vented cap instead).
If your car does have a vented cap, maybe its clogged/malfunctioning/stuck shut. |
Craig Dewey (Craigfl)
| | Posted on Monday, April 23, 2001 - 3:38 pm: | |
Usually, tanks are vented thru a carbon filter and with a valving system sucked back into the intake manifold. Since mine is a non-US version I wasn't sure if it would be the same. I just was concerned that the pressure that was there might cause leaking and/or other problems. Using a vented cap may cause another set of problems because of the fuel injection. |
Ben Lobenstein 90 TR (Benjet)
| | Posted on Monday, April 23, 2001 - 1:01 pm: | |
IIRC, they got rid of venting automotive gasoline due to some sort of emissions thing. I can recall a friend of mine with a vintage motorcycle having a VERY tough time finding a replacement vented gas cap. Different scenario, but same issue.
OK thinkinng back on that maybe it was just to keep the Harley guys from blowing themselves up (thinking they are lighting up a smoke after the ride)...oh well...
-Ben |
Michael A. Niles (Man90tr)
| | Posted on Monday, April 23, 2001 - 12:24 pm: | |
I get the same thing in my TR in the hot Maryland and Virginia summer time. It is not as dramtic as the pop off you cited but there is a lot of pressure release. After a drive in hot weather, I always open the cap and release the pressure that has built up. I assume this is normal because gas like any liquid that is heated up will produce a gas vapor and the gas will expand. And in this case the expansion limit is the tank walls and after that the pressure will build -- no where else to go.
I fly airplanes also and my six tanks there are equipped with venting valves for this specific purpose. The TR or other street Ferraris to my knowledge has no such vent so the pressure cannot escape. Does anyone know if these cars have fuel vents?
Regular cars are probably less prone to this problem because there is no high revving, engine right next to the tank heating up the fuel.
That's my take on this. I just live with it. Lucklily in the airplane the fix was designed in from the start. |
Craig Dewey (Craigfl)
| | Posted on Monday, April 23, 2001 - 6:43 am: | |
I went to add fuel yesterday and when I got to the last few threads on the cap it popped off in my hand because there was so much pressure in the tank. The tank was about 1/4 full, temp 85 degrees F, and I'd been driving for about a half hour. Is this normal? BTW, it's a Euro, if that makes any difference... |
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