Fuel Overfill Problems.

[lvlagnum]

A friend of mine who is a mechanic told me that overfilling the fuel tank on a vehicle past the point where the automatic shut-off turns off the pump at the gas station can risk saturating and clogging the charcoal canister and hoses and cause reduced mileage and other problems. Is this true and if so what other problems can this cause? I have a 2003 Chevy Silverado 5.3 Z-71 and have never had any problems like this and I have a 2009 GMC Sierra 5.3 Z-71 on the way. If this is true, what model years of GM trucks are more prone to this?

 

Cheers, lvlagnum.

[svensk]

I've heard it is bad also. I never do it. I figure if it's designed to shut off at a certain level why bother pushing it?

[jwdpveen]

This is true and if you live in an area where you have to pass emissions the charcoal canister needs to be replaced ($100 to $300) dependeing on model of vehicle. What happens is the vehicle runs rich and burns out your o2 and cat, even more $$.

I used all way top off my tank, but have been converted to stopping when the pump stops.

[Nick The Great]

I've always heard that's a bad idea, but because you get cheated $ if you try to top it off. Something about liquid changing to gas. Don't know if it makes much sense, but I never go past the autofill line. I pay with a credit/debit card. That extra 2oz of gas won't get me that much further.

 

I pulled up to a gas station a few weeks ago, and gas was just spewing out of this Corolla. Like Old Faithful. I quickly hopped out and shut if off, figuring the guy was inside. There were 3 women sitting inside. They looked at me, and gave me the WFT look as I shut off her pump. The lady got out of her car 5 minutes later, and said, "Is it just me, or is there gas on the ground?" She had put 24 gallons "in" her car.