Gas leaking from gas cap

[golden86]

For some reason I have gas leaking out of my vented gas cap.  I'm  not quite sure how its getting out but after a drive, there is gas allover the back of my car, and on my hot exhaust  .  Does anybody have any idea of whats going on?

Here is the filler neck I'm using, and the location its installed.  The fuel system is from a 94 if that helps any.

[kiwicanfly]

Possibly just sloshing around? Depends on the length and routing of the hose from cap to tank.

Simple fix would be to take a hose from the breather and then add a rollover valve, let's air in but not fuel out. Hose is to allow valve to sit vertical.

[einy]

Breather hose has to be able to exhaust air from the tank as it is being filled ... that is why it is there. Putting a check valve in that line to keep air from moving out of the tank would defeat the purpose of this hose.

Sounds to me like your Perko cap is messed up. It should seal everything in when the cap is fully tightened (i.e. - it allows air in to replace fuel as it is burned, but does not let fuel or vapors out). Unless you don't have the EPA version, which may not have this check valve function.

[golden86]

I fixed it.  I epoxied the vent on the cap it self, that is where it was leaking from.  There should be no problem with pressure build up since the factory tank has a relief valve on the top.  I did not touch the valve on the neck, since I need that to fill the tank properly.  I drove it around for a while and there is no sign of a leak anywhere.

[zeitgeist]

Apr 11, 2016 22:04:01 GMT golden86 said:

I fixed it.  I epoxied the vent on the cap it self, that is where it was leaking from.  There should be no problem with pressure build up since the factory tank has a relief valve on the top.  I did not touch the valve on the neck, since I need that to fill the tank properly.  I drove it around for a while and there is no sign of a leak anywhere.

Any chance that you have had the car at the track or autocross since epoxy on the fuel cap vent? I was just at a trackday with the same filler and had fuel spray coming out. I added and changed clamps and tightened everything but still had fuel getting to the rags I wrapped around it with duct tape. The O ring seemed like a poor fit.

[einy]

Do you guys have the EPA compliant version (which should be sealed to hold pressure / fuel in, yet still allow entry of air to replace the fuel being used), or the non-EPA version (which, I assume, is not sealed)?

[zeitgeist]

I believe mine says EPA compliant and it does have a valve in the cap portion but I don't find a hole for the valve to vent to anywhere on the cap.

[golden86]

Jun 8, 2016 0:48:22 GMT zeitgeist said:

Apr 11, 2016 22:04:01 GMT golden86 said:

I fixed it.  I epoxied the vent on the cap it self, that is where it was leaking from.  There should be no problem with pressure build up since the factory tank has a relief valve on the top.  I did not touch the valve on the neck, since I need that to fill the tank properly.  I drove it around for a while and there is no sign of a leak anywhere.

Any chance that you have had the car at the track or autocross since epoxy on the fuel cap vent? I was just at a trackday with the same filler and had fuel spray coming out. I added and changed clamps and tightened everything but still had fuel getting to the rags I wrapped around it with duct tape. The O ring seemed like a poor fit.

Yes, the O-ring is a horrible fit.  I replaced it with a much fatter O-ring and absolutely zero fuel leaking by.  The only down side is that the cap it pretty tight when trying to unscrew, but not impossible.

I bought this set from harbor freight for $8

[zeitgeist]

Great Thanks for the info.

[jmills]

I had fuel coming out of my vent line on hard rights at a track day on Monday, definitely need to add a check valve to the set up. Also had the same overflowing even when parked when I filled the tank all the way. Thus continues the care and feeding of an Exocet. I'll be keeping the tank to ~3/4 full max until I get the check valve put in. All that said, the car handles with scalpel precision and accelerates like a rabbit. Can't wait to get more track time.