Gas tank mod worked or the gas pumps are reading wrong.

[Turbo1dr]

Seems like I'm always traveling on the interstate with the Malibu. Recently, I've noticed I couldn't get the fuel tank as full as I once did. Today, I removed the tank and found that the vent wasn't allowing all the trapped air to escape very fast when filling up. So, I removed the vent (actually a roll-over valve) and drilled out the .060" orfice that the factory placed in the vent line. This allowed the trapped air in the tank (when filling up) to vent faster so you can get more fuel in the tank. (I have a factory GN fuel sending unit in my car so you guys have the exact same set-up.)

After pulling the tank and siphoned out 2.5 gallons of fuel until the tank was completely empty. I done this just so I could find out how much "reserve fuel" I have before actually needing to stop again to fuel up. It turns out my (digital) fuel gauge shows 3 to 5 percent fuel remaining with 2.5 gallons left in the tank (gauge may not be exactly correct).

Anyway, this is where it gets screwed up. After doing the orfice mod I put the 2.5 gallons of fuel back in the tank and then I went out to fill the tank up at a local gas station...which is about 1 mile away from the shop where I done the work. I put in 20.5 gallons of gas in it until I could see it in the filler tube! I can't believe the FACTORY TANK holds 23 gallons of gas! I think the gas station's tank is reading the amount of fuel WRONG.

How many gallons have you guys ever put in your tanks with just one fill up?

 

[Victory]

Just so I understand...

The gas station charged you for 20.5 gallons of gas but (based on your analysis of your tank) you actually received something less than 20.5 gallons of gas?

I hope the station isn't pulling a fast one on its consumers.

 

[Turbo1dr]

That's right. Based on what the factory tank holds it's kind of hard to believe it held 23 gallons of gas. If the modification I done allowed 6 gallons more to be added to the tank then I'm happy it does hold 23 gallons. To be damn sure it does hold 23 gallons, I could siphon out all the gas and be 100% sure I got what I paid for.


I also got an e-mail about a month ago that someone else in my area has also had this happen.

 

[BlackBandit]

If you suspect the station is not providing the correct amount of gas file a complaint with the weight and measures dept. in your state.