[alexwhittemore]

I've been having an increasingly bad problem lately where, when filling up at a gas station, the pump will shut off prematurely. I usually run the tank down to near-ish empty, so I usually have a good sense of how much to put in, and the pump will shut off at 8 or 10 gallons when I know it should take 12 or 14. Sure enough, I put the key in and it's under-full. I've taken to filling with the key in so I can spot the gauge.

But besides being annoying, it's actually pretty bad - if I just ignore the pump shutoff knowing I have more tank room, it'll actually overflow. Never, like, gas spilling everywhere on the ground, but if I'm too fast about it, it'll back up into the fill port a bit.

Lately, it's even worse. Previously, the tank had to be close to full and I'd miss the last little bit. Now, it'll start the shutoff BS around half full, and I have to sit there fill-wait-fill-wait-fill-wait for 15 minutes.

My searching has turned up things like "clogged breather tube" which seems to actually be the vapor return line to the manifold. Bentley on page 160-3 seems to call the tube that lets displaced air escape the "refueling ventilation line." I strongly suspect that the "refueling ventilation nipple" is clogged somehow.

Have you run into this problem or do you have tips for how to inspect/unclog the vent nipple? I'd love not to pay someone too much for diagnosis and fix.