GLENN STONEHAM Posted May 19, 2006 Share Posted May 19, 2006 I"ve had my supra for over 7 years now and whenever I fill up (usually towards empty) theres always a release of pressure when undoing the fuel cap. After all these years I"m wondering if thats normal. Glenn. Quote Link to comment Share on other sites More sharing options...
Bob Posted May 19, 2006 Share Posted May 19, 2006 yes Quote Link to comment Share on other sites More sharing options...
GLENN STONEHAM Posted May 19, 2006 Author Share Posted May 19, 2006 Thanks Bob Quote Link to comment Share on other sites More sharing options...
Bob Posted May 19, 2006 Share Posted May 19, 2006 no problemo, here to help Quote Link to comment Share on other sites More sharing options...
Kranz Posted May 19, 2006 Share Posted May 19, 2006 I"ve had my supra for over 7 years now and whenever I fill up (usually towards empty) theres always a release of pressure when undoing the fuel cap. After all these years I"m wondering if thats normal. Glenn. Glenn, its entirely normal. All cars with EVAP controls, that keep the petrol vapours inside the tank to stop them releasing into the atmosphere, do this. There's a system that takes the vapour & passes it through a charcoal cannister in the engine bay (black box with pipes on passenger side of engine bay I think, by the front suspension mount). These are fed, through a purge sysyem, into the engine to be burned. The system operates on a slight positive pressure to keep the flow of vapour into the engine. The lower the level of fuel in the tank, the more vapour & presure there is. As you take the cap off it blows out a little. A small whoosh is normal, spiting fuel out is not normal and means a line is blocked (so I'm told). Quote Link to comment Share on other sites More sharing options...
GLENN STONEHAM Posted May 19, 2006 Author Share Posted May 19, 2006 k14 sup; Thanks for informative response. Despite a fairly wide spectrum of experience with performance & other car mechanics there are some areas where I know nothing Thats where this forum/club is so rewarding for us all. Quote Link to comment Share on other sites More sharing options...
Jake Posted May 19, 2006 Share Posted May 19, 2006 Is it positive pressure? I had always thought it was a vacuum due to the volume of fuel that had been used. Live and learn. Quote Link to comment Share on other sites More sharing options...
LeeT Posted May 19, 2006 Share Posted May 19, 2006 Is it positive pressure? I had always thought it was a vacuum due to the volume of fuel that had been used. Live and learn. i had always thought it was a vaccuum as some members have said that they cant remove there filler caps due to it. the suction keeps it in place Quote Link to comment Share on other sites More sharing options...
green_dragon Posted May 19, 2006 Share Posted May 19, 2006 Is it positive pressure? I had always thought it was a vacuum due to the volume of fuel that had been used. Live and learn. That's what I thought too:rolleyes: Quote Link to comment Share on other sites More sharing options...
MKIVDreamer Posted May 19, 2006 Share Posted May 19, 2006 i had always thought it was a vaccuum as some members have said that they cant remove there filler caps due to it. the suction keeps it in place Intersting, in my experience its always been positive pressure. In fact I've had the filler cap almost blow out into my hand a couple of times... Quote Link to comment Share on other sites More sharing options...
Rob Posted May 19, 2006 Share Posted May 19, 2006 Excessive positive or negative pressure would manifest itself in the same way, the pressure would make it difficult to remove the cap. So it probably wasn't a vacuum, unless it sucked your tie into the filler neck as you bent over and undid it. Quote Link to comment Share on other sites More sharing options...
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