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Tue Dec 04, 2007 10:09 am

Since I've had my Vanagon (over a year now), it continues to "burp" gas back at me when I fill it up. No matter if I pump gas slow, or hold the lever down, I always get a swell of gas that drains down the body, below the gas nozzle fill hole.

Is this common? I always have to take a few paper towels and wet them, then wipe the side down. I find it impossible to calculate when it's almost full so I can trickle in the last gallon or so.

Any trick?

And no, none of my gas tank seals are leaking.

Tue Dec 04, 2007 10:11 am

Not sure. Mine has never done that.

Tue Dec 04, 2007 10:15 am

I get a bit of gas dripping down the side about 50% of the time I fill up. There are several gas stations where this doesn't happen (Costco is one that comes to mind) and I try to fill up at those. When the auto shut off clicks, I always wait about 5 seconds or so before removing the nozzle, sometimes that helps, other times not. I always try and keep the nozzle pointed up when removing it too. Here in CA, the vapor return portion of the nozzle (the black coiled shape thing on the nozzle) I think may capture some of the excess.

Tue Dec 04, 2007 10:21 am

It's not dribbling out when I remove the nozzle; but rather it "blows back" during refill. Gas pumps into the tank, but when the tank gets full, I get about a half cups worth that overflows from the filler neck. The pump handle is supposed to detect the fumes when the tank is full, but this does not seem to work. It has happened at 2 different gas stations.

The "unleaded only" flap is still there in the filler neck (about 2 inches from the opening).

Tue Dec 04, 2007 10:35 am

Mine does it too... it pisses me off. It seems to help some if I remember to drop the flow way down when I get up to 12 or 13 gallons, but I topped up last night and forgot to do that. I figured it's just the geometry with the filler so close to the height of the top of the tank but it sounds like some folks don't have the problem.

Tue Dec 04, 2007 11:01 am

I've discovered that lifting up on the filler hose usually prevents this from happening.

Tue Dec 04, 2007 11:09 am

Mine, too (and it's an '84 like yours Bucko, if I recall) and no amount of drizzling the last gas in seems to fix the problem. My hunch is that it's a design flaw where the bottom of the filler neck is so close to the top fuel level that it can't help but burp when the fuel level hits the top.

Unlike a lot of you, I've never taken a Vanagon fuel tank out so I do know if this theory is accurate, but that is what it feels like.

Tue Dec 04, 2007 11:17 am

All of my Vanagons have done that too except when I've refilled them at stations with gravity feed gasoline dispensers. I think that modern gasoline pumps deliver the gas at such a high volume that the aforementioned design of the filler/tank can't handle it.
Oh, and the last station I encountered with the old fashioned gravity feed was the Wildlands Grocery and Service Station. It's located just off the Matagamon Tote Road in northern Maine. Probably not where you would go for a fill up.

Tue Dec 04, 2007 11:19 am

http://auto.howstuffworks.com/question25.htm

Here's why lifting up on the filler hose works. The Vanagon filler tube must be at the wrong angle and the stop hole in the nozzle does not get covered with fuel until it is too late. Lifting the hose lowers the sensing hole so it is more likely to get covered in fuel.

Tue Dec 04, 2007 11:59 am

Bucko- that is so weird you mention that. I had an '84 that would do that too. I never understood why. My 87 has never done it.

Tue Dec 04, 2007 12:22 pm

Try putting the nozzle in upside down. Make sure its stable and wont fall out though. This did the trick most of the time when i worked at a gas station.

Tue Dec 04, 2007 12:38 pm

My '87 has always done this, so I don't think there's any difference from early to late models with the neck size change. Maybe this was the reason they upsized the late filler necks, but if it was it didn't do any good. It's damn aggravating. It's often windy around here, so you had better stand upwind when filling or the spitback gets blown onto your legs. Yellow Rabbit's explanation makes the best sense. I've been able to avoid the spew by riding herd on the nozzle when it nears full. If I can hear the gas coming up the filler neck, I can back off the nozzle trigger to a low flow and it reaches shutoff without spitting.

Tue Dec 04, 2007 12:59 pm

Mine also did this. But not any more! By tipping the nozzle (handle up / tip down) you get the gas to flow down the bottom of the filler tube which lets displaced air escape out over the flow. Since I started filling like this I no longer spill a drop.

My theory and what it is too.

Tue Dec 04, 2007 2:37 pm

Perales wrote: Mine also did this. But not any more! By tipping the nozzle (handle up / tip down) you get the gas to flow down the bottom of the filler tube which lets displaced air escape out over the flow. Since I started filling like this I no longer spill a drop.

I'll try this on the next fill up.

Thanks to all who responded. I figured I had a clogged vent seal or something, even though I never see any leaks, nor smell any fumes (other than those that are caused by the splash back during fill up).

Tue Dec 04, 2007 4:43 pm

I've been pausing before the auto-off and doing well, but, Winston, too, sins in this way sometimes. I'll try the inverted fill.

Best!

Tue Dec 04, 2007 6:22 pm

Fellow 1.9er here. I too suffer the embarrassment of fluid leakage.

Okay, let me calrify, my fuel tank suffers, not me personally. :lol:

I'll try the tilt and fill method.

Tue Dec 04, 2007 9:55 pm

My 84 does this too, but I've found that if I really pay attention I can hear a change in the noise that the gas going in to the tank makes just before this is going to happen, so sometimes I can avoid it.

It weird, I dont remember my 82 doing this, and I know that my syncro didnt, but that had a whole different problem...just getting gas in the tank.

-Glenn

Wed Dec 05, 2007 11:04 am

Well of course the syncro has an entirely different tank and filler, so there's no point in comparing that. What is strange is how some 2wd vans do it, and some don't, and it doesn't seem to respect which filler neck size you have.

I never bothered to look up how a gas filler nozzle shuts off, so that's new info to me. I knew it had to be something simple since these have been around since anyone can remember. There would be differences from one gas station to the next, as the calibration of the vacuum shutoff valve could vary from pump to pump, and the service each station does on its filter system varies as well. As the filters fill up, the rate of delivery goes down (ever wonder why some pumps just fill your tank so slowly? It just means the filter is backed up and needs servicing). The spitting obviously has to do with the rate of delivery as the tank reaches full. The fuel surges up the filler neck and is heavily entrained with air, so there isn't a definite blocking of the nozzle vacuum port before the surge blasts past the nozzle and out the neck onto my shoes. When I slow the delivery rate nearing full, both the air entrainment and rate of rise are much less, so liquid fuel rises to the nozzle tip and it shuts off.

I had had my two expansion tanks out this year because one had a small leak at one of the breather lines, and I noticed that the inlet ports on the very bottoms of the tanks are tiny pinholes. Believing that one of the reasons for the puking filler neck might be a buildup of air within the system as fuel is rapidly added I decide to try an experiment in freeing the breathing somewhat. I drilled the inlet ports out to 1/8" holes and reinstalled my tanks. This has seemed to help a bit, as the neck pukes a little less often if I forget to attend to the nozzle while I'm cleaning the windshield, but the problem is by no means solved.

Turning the nozzle sideways or tipping the tip downward seem like things that will help, so I'm going to alter my technique and see, but I would still like to be able to fill my tank unattended. I'm going to be thinking about this some more and maybe I can think up some mod that would make that possible. Then I can get some new shoes.

The obvious remedy would be to make the filler neck even bigger, as that would slow the surge rate of the fuel up the pipe. That's probably what VW was aiming at with the size change they did do, they just didn't go far enough.