Gas Tank "Short Fills"

When I fill the 14.5 gallon tank on my 2009 Nissan Sentra, the gas pump clicks off “I’m full dummy!” yet the needle gauge is at anly 3/4 full. It stays that way even after driving 10-15 minutes, long enough for a slow needle the eke its way up. I always end up pumping more in until the needle is at Full. There’s no gas overflow when I do this. What’s up with that??

Gas pump hoses have a pressure sensor on the filler neck (look for the small tube running from the tip of the filler back to the handle). When it senses a back-pressure, it shuts off the pump. Every car has a different shape pipe from the gas cap to the tank. Gas pump pressure switched are set to the lowest possible level to shut off and can not detect the difference between makes or models of cars.

Your fuel level sensor in your tank may be slow or starting to fail.

This can be caused by pulling the handle on the filler all the way closed and letting it be held by the last little metal ridge on the filler. Try holding the handle with your hand and pumping gas at less than the maximum rate.

While searching TSB’s for other issues I am amazed at how many TSB’s there are for tank filling issues,have you checked? let me take a look but with your car being a 2009 it may be to early.

EDIT: as expected no EBSCO TSB’s for the Sentra yet but for 2008 there is a TSB for “tank filler tube out of position” trouble is when I try to view the TSB I get a “file not found” message. This happens much too much with EBSCO.

EBSCO is the source I have available to me to view TSB’s. It is not the only source out there.

Thanks for some great info I didn’t have before!! How about this: my husband (who has been driving my car–long story) asked some auto mechanic somewhere and the guy said it’s because hubbie needs to TURN OFF THE ENGINE WHEN FILLING THE TANK!!! He did, and it worked, but now I get to hassle him about all the times I told to turn the engine OFF at the pump, but, duh . . .

EVERYONE should ALWAYS turn off the engine while filling. It’s a safety thing. Also, running the engine while filling will cause the dreaded check engine light to come on. It’s the same code as that for a loose gas cap. Something to do with evaporative emissions.

To the best of my knowledge, it is against the law to fill the tank with the engine running. After living across the street from a gas station for many years. I can tell you that filling the tank with the engine running is a very bad idea.

While I definitely agree with turning off the engine, I pumped gas for about 4 years as a teenager and commonly pumped gas into cars with the engines running.

Me too, plus I was smoking a Camel. :wink: