Overflowing at the pump

[mac]

When I go to fill up the truck, I gotta stand right next to the filler so I can manually shut it off (we've got 2 feet of snow in less than 2 days and it ain't lettin up... I'd rather sit in the cab and wait). If I don't shut it off, it just keeps going and going and going and it overflows and pours out all over the ground.
It happens in both tanks.
Why would it be doing this?

 

[jperecko]

It is the pump, not your truck... the pump should shutoff automatically when it contacts fuel. I had this happen at a pump once and you could see all the stains on the ground where the same thing happened to everybody else. I wanted to ***** at the counter but was in a hurry.

 

[mac]

Hmm. So it has nothing to do with pressure in the tank or anything?
I don't like that pump anyway, it takes a good 10-15 min to fill up one tank (its real close though.
I'll try a different station next time I need to fill up and I'll let ya know what happens.

 

[02AutoWag]

Pump automatic shut-off explained:
http://www.straightdope.com/columns/read/230/how-does-a-gas-pump-know-to-shut-itself-off

 

[mac]

So how does it know when to slow down and let the fuel just trickle in?

 

[jperecko]

So how does it know when to slow down and let the fuel just trickle in?

I do not think any pumps I have ever used do that... it is either on or off. If you want to go slower than all the way you will have to hold the valve only part-way open and it will still shutoff if it contacts fuel/foam.

 

[LCAM-01XA]

They slow down when you're like $0.25 away from what you prepaid for. If you're running on credit card or told the attendant to juts keep her rollin the pump will just run full bore till tank is full (or, in our case, till diesel foam reaches the nozzle) then she'll simply shut off.