Oil & Fuel MF 6255

[mic mac dad]

I have a MF 6255 that has diesel fuel leaking down the back glass of the cab. It appears the fuel tank vent goes up through the cabs frame to the top? Fuel must be being forced up through the vent then dripping on back glass. Any ideas what could cause this?

 

[MIKE R]

Was there a rise in temperature recently? The vapors most likely have expanded in the heat. Take the fuel cap off slowly to let the vapors out. Welcome to the forum.

 

[mic mac dad]

Good thought but temperature doesn't seem to matter. It only occurs when you are running the tractor. The fuller the fuel tank the worse it is. Tank does seem to be under slight pressure when running so I wonder if vent is blocked but how would fuel pass through it and not air. My guess is it is vapors, but why?