This is a more common problem than you might imagine. Because air has to escape the fuel tank to allow the fuel in, you can sometimes achieve what is pretty much an air lock when the nozzle prevents the air getting out fast enough. Either that, or the fuel filler neck is shaped so that it splashes the fuel back against the pump nozzle, making the sensor in the nozzle think the tank is full.

Some cars will be fine on some pumps and not others, while some cars are just generally a pain to fill. Yet other cars will be fine on a flat surface, but won’t fill properly on any sort of an angle or slope.

The best trick to try is to insert the nozzle into the filler neck and then turn it 90 degrees. This has the effect of directing the fuel spray somewhere other than straight back up the nozzle’s spout and triggering the pump’s shut-off mechanism. The other thing to try is to pull the trigger on the nozzle, but not all the way. That can sometimes slow the flow enough to prevent the shut-off. If that doesn’t work, you’re stuck with trickling the fuel in very slowly to avoid the pump shutting off.