Fuel bled from left tip to right main ???? How??

[Daverehm]

I filled up all four tanks on my Cherokee 235. I flew for around an hour. 30 min on right main, then 30 min on left main. When I got to my hanger my passenger noticed gas coming out the drain valve on my right main. I took the cap on my right main and it was completely full. I checked the rest of the tanks. Rt tip full, left main looked right(around 18 gallons left) but the left tip was only half full. Any idea how the left tip tank could bleed over to the right main?

Any ideas?

 

[vaflier]

 

[BGFYankee]

 

[Daverehm]

 

[vaflier]

 

[bill7]

 

[herkster]

 

[Daverehm]

 

[rrc1962]

 

[herkster]