Small fuel tank?

[m1dn]

Got a new to me 2008 XL Denali.
The tank seems to be smaller than in tech papers and i cant fill it full, any ideas?

Emptied it down to 30miles remaining with light on.
Filled 20.5 gallons and it wouldn’t let me go further.
Gauge shows 3/4 and a half.

Last few fillings same, won’t let me go further.

I don’t have any records of fuel tank being replaced, but found online they’ve put both 26 and 31 gal tanks.

Anyone ran into similar issues by chance?

 

[gooffeyguy]

The 26 gallon tank is in the short wheelbase Yukons and Tahoes while the 31 gallon tank is in the long wheelbase XL and Suburban.

If you're have problems filling it fully then it might be a tank venting problem. Sometimes the EVAP system gets clogged and the lines need to be replaced or blown out.

 

[Geotrash]

Got a new to me 2008 XL Denali.
The tank seems to be smaller than in tech papers and i cant fill it full, any ideas?

Emptied it down to 30miles remaining with light on.
Filled 20.5 gallons and it wouldn’t let me go further.
Gauge shows 3/4 and a half.

Last few fillings same, won’t let me go further.

I don’t have any records of fuel tank being replaced, but found online they’ve put both 26 and 31 gal tanks.

Anyone ran into similar issues by chance?

Yup. I agree with @gooffeyguy that you have a fuel tank venting problem. The charcoal canister has a permeable media that contains charcoal pellets. Over time, that membrane breaks down and the pellets flow into and clog the vent lines to the tank, triggering the gas pump handle shutoff, and preventing you from being able to top it off. Lots of threads here on it and several helpful YouTube videos. I replaced the canister on my 2012 just a couple of weeks ago as a preventative measure. Easy job to replace the canister but cleaning out the lines can be a PITA if the pellets have been released.

 

[Fless]

Your fuel pump could be reporting the level improperly, setting the low fuel light early. You could carry a 5 gal gas can with you and run it empty, then fill and see what it takes (including the 5 gal).

 

[m1dn]

Thanks folks! Will try charcoal canister to begin with and see if the issue persists and what else.

Wonder if gauge is also borked then? Since i fill 20 gal and the gauge shows almost full, indicating maybe another gallon or two could fit at most

 

[Fless]

Do yourself a favor and don't keep filling after the pump clicks. Overfilling can ruin the charcoal canister.

 

[BlaineBug]

Do yourself a favor and don't keep filling after the pump clicks. Overfilling can ruin the charcoal canister.

That's what I'm concerned with. Earlier this year in March the local Meijer Gas Stations' E85 pump never shut off and I only realized it when fuel was pouring out of my 2019's filler neck.

I contacted Meijer customer service to document and they gave me a $25 gift card.

Now nearly 6 months later I haven't noticed any issues and I'm hoping I never will, but this was a concern of mine!

 

[OR VietVet]

Your fuel pump could be reporting the level improperly, setting the low fuel light early. You could carry a 5 gal gas can with you and run it empty, then fill and see what it takes (including the 5 gal).

I just replaced a fuel pump on a customer's 2003 Escape for the exact same problem. No problems putting fuel in but was getting incorrect info at the gauge. He just had a new fuel pump put in elsewhere for a no start no fuel problem. Then the gauge problem started. He had a cheap aftermarket pump in it and when I showed him the difference in the new Motorcraft pump and the one I took out, he was amazed. Really cheap resistance scale where the fingers on the float arm rubbed. He has had no problems now, going on about two weeks. Or, you have a vent problem like has also been suggested.