So, for some reason my mini 04 dies but can be re-started by simply taking off the gas cap for a second. But, my question is, at the top of the filler neck there is a hose. What is the purpose of that hose? I've seen diagrams where some cars seem to have several hoses coming off the neck near the tank. Cheers-RKL

 

It is a pressurized system with essentially two tanks ( saddle tank ) so theres a float in the tank on both pass and drivers side. I have seen where a faulty MINI fuel cap will actaully produce a code too.....Oddly enough, my John Deere Tractor acts up in same manner due to a small pin hole in the center of gas cap which can plug up with dirt....have had to clear it out a few times with piece of wire. Not sure about the hose, other than a drain for excess fuel spillage ?

 

Right--the mystery remains. It's so weird. My mechanic says there is an evap leak but it shouldn't cause the car to die while driving. The car literally starts right away when you unscrew the gas cap. So weird. I was really just trying to figure out what all the elements are to the whole system. Someone else said it could be the charcoal filter near the tank. Other's said PCV. Cheers, RKL

 

Maybe just replace the filler cap ? Or borrow one from an owner of an 1st gen.

 

Harleys with the old style double tanks had one vented and one non-vented gas cap to prevent air locks and equalize gasoline across the tanks.. Could be the same issue you're having.

 

Have you noticed any issues when filling the tank with gas? If it clicks off and is hard to fill the vent valve for the evap system (vents the canister vapor) had failed in the closed position and preventing the system from venting. Opening the gas cap releases the vacuum on the fuel system and allows the pump to draw fuel without restriction again. I've seen plastic fuel tanks collapse under vacuum when the evap vent valve has failed. Usually you qill see a CEL and code for this situation, though.

 

I saw this video a while ago and thought it may at least be food for thought. Really hopes it helps somehow or provides a cue;

 

Your Mini has a fuel tank vent on the passenger side of the engine. It's possible that it's clogged and could be your problem.

 

It still boggles my mind why they call this a vent valve when the rest of the automotive world considers it a purge valve. The purpose of the valve at the engine is to purge the fuel vapor that's built up in the charcoal canister into the intake manifold so those vapors get burned in combustion as opposed to vented to the atmosphere. This valve is normally closed and is only opened under a pulsed signal from the ECM when it determines the conditions are right. It would not cause this type of concern.

There is also a valve that vents the charcoal canister and the fuel tank that is located on the charcoal canister/leak detection pump assembly by the right rear wheel well. There is a hose that runs from this valve up behind the wheel well liner and allows the fuel tank to displace air when filling the tank, and to take air in while the tank gets pumped out to keep the tank from collapsing. That vent hose could be clogged, or the valve could have failed in the closed position. It is normally open, allowing the system to vent for events like fuel fill ups, and is only closed by the ECM under certain conditions. This would be the valve and failure that could lead to this type of concern. It would also lead to issues with filling the tank with fuel, causing the pump to click off often as the filler neck backs up and making it difficult to fill the tank.

 

Thing is though, and you could be correct, but when the vapor line is disconnected from this component, I had it throw a code on mine.....not sure but so far no mention of a code yet by Op.

Could always disconnect it and see if a code comes up.

Would think that if code comes up then its probably functioning properly ?