Fuel tank capacity and fill-up

[Mid Mod Guy]

I took my 63 Avanti to the gas station today. The fuel gauge showed one mark above empty. I put the gas nozzle all the way into the filler neck and filled it until it clicked off. I assumed it was full. But it only took 6.7 gallons. I was afraid to fill it more due to the risk of spilling fuel on the body.  Is it true that our cars have 21 gallon tanks? If so, do others find that gas pumps click off too early? Should I keep filing it further? Perhaps something about the design of the filler neck signals the pump to shut off too soon, or maybe my fuel gauge is inaccurate. I'm looking for experience here.

Note: I had a Triumph Spitfire that had the fuel tank filler just in front of the trunk lid, right behind the seats, in the center of the car. I once overfilled it and gas poured and sprayed everywhere, and with the top down, it was not pretty. So I'm hesitant to overfill.

 

[Gunslinger]

The gas tanks are rated at 21 gallons but many have reported they can't get that much into them.  It's best to not fill them all the way...especially in the heat.  The gasoline will expand and go right up and out onto the quarter panel quickly if the car is parked on any kind of slope.

To save the panel from damage from the pump handle you can cut a piece of thin rubber and mount it on the filler neck.  On the '70 I had I tried one cut for a '78 Corvette and it worked beautifully.  

[Mid Mod Guy]

Thanks @Gunslinger.  My car came to me with a slight discoloration from gas spilled below the filler, so I will definitely be cautious.

[Gunslinger]

Here's what I did for the '70 Avanti I recently sold...this is a pre-cut piece of rubber made for a '78 Corvette that Corvette specialty companies sell.  It works just fine and folds up neatly behind the gas cap door.

Edited August 5, 2019 by Gunslinger

[Avanti83]

2 hours ago, Gunslinger said:

Here's what I did for the '70 Avanti I recently sold...this is a pre-cut piece of rubber made for a '78 Corvette that Corvette specialty companies sell.  It works just fine and folds up neatly behind the gas cap door.

 

An excellent idea. My 83 came with a similar piece installed by the factory. This is a great solution for the earlier models. 

[Dan S]

I couldn't find one for the Corvette, but this one for a Porsche 911 that looks like it should work.  I ordered one and will post the results when it arrives.  https://www.aasesales.com/products/g4b-a82-b-102400?variant=7681388838940

 

[mfg]

As far as the nozzle 'clicking off' too early, I've experienced the same thing with all of the Avantis I've owned if I fill the tank too fast.........Slow down on the fill, and it will take the gas!

PS......Assuming your fuel gauge is accurate!

Edited March 23, 2020 by mfg

[MARK]

with my Avanti R2 and my 63 and 64 Hawks, I really watch mileage. I take a cell picture when I gas up and just watch the mileage. Sometimes a full tank is really full, othertimes, I think Im driving on fumes

Mark

[Stan Gundry]

I found the protector flap pictured above

by Gunslinger for sale on EcklersCorvette.com. It was hard to find, so here is the name and the part number: Gas Guard, 25-106419-1.

[Stan Gundry]

I am sorry everyone, I chose the wrong part number in my post a moment ago. Here is the correct part number for the one that gunslinger identified: 25-107849-1

[studequest]

NIFTY IDEA GUNSLINGER

Well.,  I put in a new sending unit and clearly it is not correct because it is not moving past 1/4 tank and as I ran out of gas today that is clearly not

Normal so my new empty will be at 1/4.. When I filled up I had 18.6 gallons and it was not all the way full so I believe it must be a 20 gallon tank

I plan to go off mileage at 12 ,pg so a total of about 210 miles between fill ups PLUS a 2 gallon gas can in the trunk!!!

Edited March 29, 2020 by studequest

[studequest]

Anyone else getting over 20 gallons

Anyone with fuel gauge reading issues