Gasoline vapors causing residue on paint?

[_BenzW124]

Greetings,

I’ve been seeing this occur when not washing my car for a while.

What do you think could be the culprit? Gas cap?!!! Although the gas cap was replaced couple years ago brand new from dealership.

 

[gsxr]

I've never seen anything like that. Are you certain the residue on the paint is definitely from gasoline vapor? If the cap is new, inspect the pipe neck closely to see if it is warped or otherwise damaged.

 

[sheward]

check that drain tube to see if it's not clogged and holding rainwater. It may then be sucked out from low pressure while driving.

 

[_BenzW124]

I've never seen anything like that. Are you certain the residue on the paint is definitely from gasoline vapor? If the cap is new, inspect the pipe neck closely to see if it is warped or otherwise damaged.

Yes this is likely from the gasoline since thats the only area on the paint getting it. The neck looks normal and is not warped or anything. How do i tell if that newish cap is gone bad?!

 

[_BenzW124]

check that drain tube to see if it's not clogged and holding rainwater. It may then be sucked out from low pressure while driving.

Drain tube is clog free and water runs down easily. This is the only area that gets this vaporish looking residue on my paint.

 

[gsxr]

Check the seal on the cap for cracking. As a short-term fix you can flip the seal over if it's cracked on one side more than the other. The caps rarely fail but the seals can wear out. However, the seals should last more like a couple of decades, not a couple of years.

Note that gas vapor would likely evaporate. I'm still not convinced the residue is from a gas/cap leak... could be, but seems unlikely?

 

[Bogeyman]

I always thought gas vapor was heavier than air, therefore would sink rather than rise.
Was the car washed after the last fill?

 

[_BenzW124]

I always thought gas vapor was heavier than air, therefore would sink rather than rise.
Was the car washed after the last fill?

No the car was not washed

 

[_BenzW124]

Check the seal on the cap for cracking. As a short-term fix you can flip the seal over if it's cracked on one side more than the other. The caps rarely fail but the seals can wear out. However, the seals should last more like a couple of decades, not a couple of years.

Note that gas vapor would likely evaporate. I'm still not convinced the residue is from a gas/cap leak... could be, but seems unlikely?

Will check the seal and see what shape it’s in.

 

[gerryvz]

That does not to me look like anything having to do with the gas cap/gasoline system. Also, if the car's fuel system were leaking vapor to that extent, you would smell it no question. Even a small fuel vapor leak is very easily detectable. There is no fuel vapor leakage problem here.

That is a dirt and spray stain. Gas vapors are just that -- gaseous vapors. They do not contain nor could carry the level of dirt that is on that gas cap. Not to mention could they escape and then be deposited in that type of pattern.

Your gas flap area behind the hinged flap is very, very dirty. There is a fairly decent possibility that it is dirt from behind the hinged gas flap area, perhaps if water got in there while you were driving. Have you not washed that area out when you wash your car?

I recommend that you wash off the dirt/spray from the outside of the car, and thoroughly clean the area inside the gas flap, and see if it returns. This should only take five minutes or so. Use some Simple Green or other mild cleaner and a brush to spray and soak the gas flap area in there, and then rinse it out the drain with water.

I think then you will see your problem alleviated. It's just dirt from in there -- nothing to do with any gas vapors.