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Was curious how much more fuel my 2007 Cayman S would take after a first click from the gas station fuel line. So, I continued filling until on the slowest setting. When it got past two extra gallons, I stopped, becoming worried just where is that much extra fuel is going. I pulled out the gas pump line, and out came a substantial splash of fuel, hitting me and my shoes, drenching the side of the car, flooding the gas filler neck area, and leaving a puddle on the ground more than two feet in diameter (and spreading). Needless to say, I don't top off the car any more. But, wonder where all the extra gas was going and why this happened. Never had a car react this way if topping off.

Phil
 

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I have also had fuel filler problems. See here: http://www.planet-9.com/987-cayman-boxster-problems-complaints/104620-fuel-filler-cutoff.html

These California pumps are a problem. They develop a lot of suction when the rubber filler ring makes good contact with the car's filler neck. As for where the extra gas is going, I think it gets sucked up into the filler hose vent. Then when the seal is broken, out it comes.

I have ordered the new collar from Suncoast, which lets some air in so the suction does not get too bad. Once it arrives I'll let you know how well it works.

Note that other posters have reported success by positioning the fill nozzle upside down or at an angle.
 

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Never top off. Gas pumps have a vapor capture system to catch excess fuel being pumped. You're just giving away free cash topping off.
 

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IIRC, overfilling can saturate the charcoal filter that prevents gasoline fumes from going from the tank into the atmosphere. Some of the excess gas that OP pushed into his tank likely when up into the filter canister. ALWAYS stop after the first trip of the cutoff (unless you are having problems with the pump - then you need to use judgement to prevent over-filling). But never try to squeeze extra fuel into the tank.
 
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