Fuel Tank Equalization Vent

[Rage]

 I've started to notice a lot of pressure required to remove the fuel cap from the right wing tank of my '68 F.  Upon removal there is a huge delta in the pressures.  I’m guessing that the equalization vent is clogged, but I can only find the single tube sticking out from the bottom side of the wing just aft of the leading edge.   From what I can tell, this tube doesn't seem to have any effect on the pressure in the tank.  Does anyone know where the equalization vent is and does the Mooney have any sort of crossover tube between the right and left tanks?

[carusoam]

There is only the one vent under the wing.  There is no cross-over between tanks.  The vent can get clogged by small insects or anything else that can get up inside.  A small wire or nylon line should be able to be sent up into the vent to clear it out.

Since the cap is not vented, and the vent seems to be clogged, the affected tank is in danger of not being able to feed fuel properly.  The vacuum will actually try to collapse the wing skin.

It is good to see that your tank does not leak....

Best regards,

-a-

[Piloto]

Do not fly until you have this problem fix. There is a chance of tearing the fuel pump diaphram. Before flight and with the cap off blow air by mouth into tank vent. If the vent is clear air should flow easily. If not the vent is clogged. When doing fuel tank resealing there is the possibility of accidentaly sealing the vent tube inside the tank.

José

  

[Ron McBride]

With the fuel cap off, I put an air hose to it, must be very low pressure, I started the compressor and shut off after 30 seconds. You will feel the air escaping the fuel tank, if not it is plugged. My A&P had me use safety wire with a circle end as to not damage anything. If you look into the tank and forward of the filler, you should see the wire come up and hit the bottom of the wing, do not force it.

Ron with a 69F