Date:         Mon, 8 May 2000 08:52:13 -0700
Reply-To:     Steve Sullivan <Steve@NORTHWESTWATCH.ORG>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steve Sullivan <Steve@NORTHWESTWATCH.ORG>
Subject:      Fuel spillage
Content-Type: text/plain; charset="iso-8859-1"

My van has not shut off the auto fuel nozzle any time I've ever filled the
tank. Many people wrote that they've had this problem since their vans were
new and they are just extra careful when they fill.

Guess what I figured out: like most people, I fuel my tank by letting the
nozzle hang there while I stand impatiently. This puts the end of the nozzle
up at the top of the fuel filler, (I think) about or--just below--where the
gas level would be to start flowing out the hole and onto the ground. So
even if the back flow of gas reaches the nozzle before the outlet into the
world, it's still not enough to shut it off in time to prevent a spill.

My solution? Stand there with the nozzle elevated, so the end of the nozzle
points as low as possible. Wa-la! Nozzle shut off just fine: no fuel spill.

Maybe I'm full of #?@$%&, but it worked for me.

Steve


                I believe auto shutoff fuel nozzles work by a slight suction
created by a
                Venturi that the fuel jets through inside the valve
assembly. On the lower
                surface of the fuel nozzle near the tip there is a small
port connected to
                a tube that runs inside the nozzle up to the valve assembly.
Air is sucked
                in through that port to relieve the vacuum until fuel or
foam reaches it.
                Then the unrelieved vacuum moves a diaphragm inside the
nozzle and trips
                the fuel cutoff.

                It's a mystery to me why two different nozzles would fail to
cut off, but
                it may be because the nozzle was not inserted deeply enough
into the filler
                opening. It's unlikely but possible that both nozzles were
defective. I
                think you need a larger sample than two fill-ups to
determine if there is a
                real problem.

                Nick
                '82 Westy, '88 Jetta, VW camper owner since '67
                Mendocino CA


                At 02:58 PM 5/3/00 -0700, Stuart MacMillan wrote:
                >Fuel nozzles cleverly detect the sudden rush of air up the
filler pipe
                >that happens as gas gets up to the top of the tank and shut
themselves
                >off.  Really slow filling can fool this system, as can
having the nozzle
                >too far out of the filler neck, but I don't think an air
leak in the
                >tank would.  My '84 does not pressurize the tank, I don't
think any
                >Vanagon does.
                >
                >The only way to fix a leak would be to drop the tank and
check the hoses
                >and tank condition.