I hope you're talking to one of the guys on this thread.

And I would never voluntarily give up the information that I ran a car out of gas...it's the cheapest thing you can put in your car and when you run out, it's quite embarassing.

 

I talked to the owner yesterday on the phone and told him my car has a 15.5 gallon tank. He "said" his pumps were just checked recently and they were fine. He offered to take a gallon gas can and fill it up to prove to me his pumps are correct.

I'm going to do some researching on this before I go any further. I'm going to assume GM has done tests on how much a fuel tank will hold, including the filler neck. I'm hoping I can use some of my racing contacts to get answer from someone in GM.

I'm a clutch specialist on a top fuel dragster and I'm off to Rockingham, NC tomorrow. I'll update you guys..and ladies on this situation when I get back.

Thanks for the comments.

Tony Smith
Zizzo Racing Top Fuel Dragster

 

I think you just messed up by talking to the station owner...you basically tipped him off that you're onto his scheme. He's now going to go reset the machine to accuracy to avoid being busted...You should have just shown up there with the agricultural commissioner and let him take care of it.

 

This is quite a debate for 3rd gen owners.

Supposedly the cars have 15.5 gallon tanks. Personally I've never put in more than 11 gallons. Even when I was jerking back and forth trying to make it to the station. 10-11 gallons max. Another guy with the same year, model, engine managed to put 16.1 gallons in his 15.5 gallon tank. Seems to me that some of the 3rd gens came with 12 gallon and some came with 15.5 gallon. Offically they're all 15.5 gallon except the 1LE cars which had larger tanks.

I hate small gas tanks. I can put more gas in my Sunbird (13.7 gallon tank) than I can my Trans Am.

 

I've had this happen to me at three other stations in the area, so I'm sure it will happen again.

 

One of the tricks theyl'l do to the pumps is set them so they are accurate at specific measurements. 1 gallon, 5 gallons, 10 gallons, 20 gallons. But they speed up between those marks and are least accurate right at the midpoint between the marks, assuming the store owner used those marks 15 gallons would be less accurate than 18 or 13 gallons and 12 or 18 gallons would be more accurate than 14 or 16 gallons. If the shop owner offered to do it right off the bat chances are thats what it is, bring 3 1 gallon cans and fill them all up at once (fill one then fill the next then the last without ending the transaction) and see how close.

 

yea, alllegedly the tank I bought for my car is a 14 gallon tank. that is the only one that advance called for, it is the exact same size as the one I had in the other car...

I only at most ever got 12 in it.. so I have no right idea how they come up with these numbers. and yes I did this in both the dead of winter and the heat of summer... and 12 is what I got... grant it I am sure the tank was not bone dry.. but I've cut it close more than once to the point the car was ready to die out *L*

how you have magically gotten more than what you were supposed to at all is beyond me.. must be the pump at the gas station.

 

That's what I've been thinking about and one of the reasons I didn't take him up one the 1 gallon test.

 

When I had a third gen, I NEVER got over 13 in it, and I once took it near to VERY empty as I could handle. Yet, everything I Read says it had a 15.5 gl tank... You'd never know though, with mine at least.

 

you do realize most tanks where this gas is being pumped from is below ground right? which means the temp of the actual gas in the tank might only vary about a couple tenths of a degree daily. that whole deal you should fill in the morning because the gas is cooler and more dense is absolutely bogus

 

a 70 degree morning versus a 100 degree late afternoon will have an effect. Like I wrote initially it is usualy very minor (1%) and the only time you would really notice it is on a really really hot day, but it is an estabilshed fact of basic chemistry.

 

Based on chemistry, all gasoline is not created equal. Meaning gas x has a different composition of chemicals in it than gas y, even though both of them may achieve the same octane rating, not to mention the impurities in pump gas. Also, there are other factors involved besides heat, one that would have a large effect would be the atmospheric pressure. Are you up in the mountains, or down below sea level in death valley? I would be surprised if you could measure a difference as large as 1% in the mole concentration between the same gas at two temperatures that vary only by 30 degrees, all other variables being held constant.

 

nice to hear good informed info

I was just not using 1% from a measurement of an experiment or anything like that but just saying that things like temperature (and other factors like you said) will have an effect, but small... But, like I said in the initial post, if it is a constant problem (lets say a few% off) at one gas station then something’s up with that gas station but if the problem is a minor effect (lets say 0.5% off) then it could be explained



BTW on the original poster if you have already called up the gas station and really want to find out if it was a real deal why not just let the situation sleep for a few weeks to let the guy forget about it... Then randomly show up and do the experiment, with say three one gallon tanks, on your own. Personally, I’d just take my business elsewhere and let bygones by bygones but that’s just my 0.2