Fuel Breather causing excessive fuel smell?

[Tofufi]

Hi all

Thought I had fixed the fuel smell problems on my bay. Anyway, my van still smells vaguely of fuel, especially on hot days. If I go for a drive, there is a definite smell of fuel when you walk past it. I've traced this to the fuel breather pipe which is venting into the fuel filler flap.

I've now removed the tank, and I can find no explanation for this at all.

Tank is fine, no leaks. No leaks on the flexible lines to it, either. The breather connections on the metal pipe in the picture are all OK, and do not appear to be perished at all.

Bit of rust, but nothing major.

The smell, when the breather is all connected up, is definitely coming from here...

but it is strong enough to make it possible to smell petrol as you walk past the van :?

The only thing I can think of is that there may be something here...

Where the pipes disappearing up behind the rear 1/4 panel. But I don't know what / where the pipes go?

Any suggestions? I'm doing my head in here, and it needs to be back on the road pretty soon

When I slosh the tank around (not in the van) the fuel breather hose does make a strong petrol smell, so I'm wondering if the breather just is not restrictive enough?

 

[Tofufi]

Well, in the absence of anything else to try, I found that the smell from the breather after sloshing the fuel tank around was significantly reduced when I reduced the size of the breather tube by inserting smaller diameter pipes sections into the line. Can anyone see a reason why I should definitely not do this?

I don't really see why my bay needs a large fuel breather line than my Beetle, let alone one with 5 times the area...

 

[froggy]

Have you tried changing the fuel cap?
When i had issues with fuel smells i changed all the rubber pipes and fitted a new filler cap, smell now dissapeared 8) , not sure what cured it but hey ho

 

[Bookwus]

Hiya Tofufi,

I was having a similar problem with my 70 Bus. As it sat in the garage after a run it smelled of raw gasoline. The area in the gas flap did smell like gas, but I expected it to smell just a bit anyway. There seems to be some transfer of hydrocarbons from the inside of the gas filler neck to the outside via the fibre seal on the gas cap. Yes, the cap is on tightly. I wasn't too upset about that.

However, I was also getting a distinctly gassy smell from the engine compartment vents just behind the rear side windows. Apparently the heat rising from the engine compartment was also carrying hydrocarbons out the vents. The strange thing (really strange I think) is that when I opened up the rear engine hatch the engine compartment gave no hint of a gassy smell. Where the Hell was that smell coming from?

Turns out that the base flange on my carburetor was slightly warped. It was allowing gasoline to make its way out between the base flange and the base flange gasket. No drips, just moist around the intake manifold flange. I sanded (used the pane of glass technique) the carb flange flat. Bolted it back up to the intake manifold and the smell is gone.

Apparently, the updraft of hot air in the engine compartment was strong enough to take those loose hydrocarbons straight up and out the vents.

 

[Tofufi]

Cheers guys

I've tried tightening up the locking fuel cap, so it clamps on better. I also restricted the fuel tank breathers, and my dad commented on it being the first time in a while that he hasn't smelt fuel as he has walked past it. Fingers crossed it is fixed