phil, I had the same problem with my '05 Ranger. Ended up being large clumps of moldy charcoal in the canister. The canister is sonic welded but came apart easy. Dumped all the charcoal out, got rid of the moldy bits,
then put what was left back in. Sealed it up and was filling up the tank normal again.

 

I've noticed this too. but instead of shutting off the nozzle, i see a leak coming from underneath the truck. This has one happened once and when I looked under there I couldn't see where it was leaking from. I think its coming around the fill up line that goes into the tank, but couldn't see a leak. suggestions?

 

I had filled the tank two days ago and for the first gallon or so it seemed to take it OK but then I heard the dreaded sound of fuel bubbling up in the neck and it shut the gas flow off. I had to just barely squeeze the nozzle handle to keep gas going in slowly without triggering the shut off. It was a day later that I found the line from the tank was disconnected from the canister so it had not been connected when I was pumping the gas. It doesn't look look this line closes off when disconnected, so could it still be a problem in the canister if this line was open?

 

Don't know. Maybe the Anti-trickle fill valve? I was just looking over p. 194 in the rave (downloaded pdf version) describing the operation of the "system".