97 Tahoe LT 4X4 Gas smell On Full Tank.

[wirlybird]

Wasn't sure which area to post this!

On my 97 Tahoe 2door when I fill the tank I get a strong gas smell outside of the vehicle until some fuel is burned off.
Nothing on the ground so no leaks. I also do not overfill the tank.
It has been like this for a while now but didn't used to be this way.

Googling but so far no clear answer!
Guessing something is blocked or has come undone?

 

[someotherguy]

It may be leaking just enough for the top of the tank to get wet. Unfortunately you may not be able to tell without dropping the tank to inspect it.

The sending unit on your particular model is plastic, and held into the tank with a large snap ring. The plastic "hat" on top of the sender could be cracked. Sometimes, the thick o-ring where the sender mates with the tank can deteriorate.

There's also a tank pressure sensor that is usually part of the sending unit but may also be a separate item on top of the tank, I can't recall on your specific year. It pretty much looks just like a MAP sensor.

Your fuel supply and return lines are quick-connect style with stainless ends that clip onto plastic nipples on the sender, but the vent line just has a simple spring clamp. Here's an example pic of a typical sending unit like the one in your truck.. (this one is from a '98/'99 C3500)

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Could also simply be a bad hose or clamp issue at the filler neck hose or the vent hose for the filler neck.

Finally, the gas cap on a sealed system (for emissions reasons) isn't supposed to vent to atmosphere, but it's possible it has gone bad, or the o-ring on it has deteriorated.

Richard

 

[Keeper]

Mine does that if I go above 3/4 tank. The plastic protective liner around the tank will get debris between it and tank and over time it will rub a small hole in tank. It will leak slow enough to smell it, but not enough to overcome evaporation. Check bottom of tank liner to see if it's wettish.