Clogged fuel vent

[RideOrFly]

After the recent finding of quite a bit of water in my right fuel tank, I ordered the fancy blue fuel cap o-rings. Before installing, I wanted to confirm that the cap was in fact leaking. So I started with the vinyl tubing connected to the fuel vent and blew. I couldn't tell that any air was moving, which was unexpected considering that I think there's a fuel cap leaking. So I took the fuel cap off and tried again. Still no air moving. Like, none at all. I tried on the left side and the test works as intended, and the air moves with the cap off. I took one of the little twist ties that was holding the hose together and stuck it in each vent. It went all the way in (a few inches) on the right, but on the left only went in about as far as the vent sticks out of the wing. Interestingly, I flew yesterday and was on the right tank for about an hour with no problems at all. This was only in cruise and within glide range of at least one airport, otherwise I used the left. 

2 questions:

1.  Is it possible that the fuel cap is leaking enough to provide adequate ventilation for the tank? Something has to be or it wouldn't keep running, right?

2. Any recommendations for clearing this? I didn't have anything with me today that I could run in there to try and dislodge anything.  

I've read through some other threads on blocked fuel vents and I'm starting to think I might not have all 9 of my lives left. 

[Will.iam]

Not sure how you would clear the block but with my vents if i blow into them with the caps on it will blow back out the vent and i can smell fuel vapor. I keep the blue scott’s shop paper towels pushed into the vent hole with the rest hanging out so that it’s easy to see and remove at the same time i remove my pitot tube cover before flight so that dirt dabbers or other insects do not try to build a nest or cocoon in the vents when it sits in the hanger or out on a ramp when traveling. 

[Hector]

.040 safety wire


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[Pinecone]

To stop this from happening again, get some long piper cleaners (Amazon).  I got red ones.

Fold over the end and put it in the vent.  If you forget them, the vent still works.

[Fly Boomer]

12 hours ago, Will.iam said:

Not sure how you would clear the block but with my vents if i blow into them with the caps on it will blow back out the vent and i can smell fuel vapor. I keep the blue scott’s shop paper towels pushed into the vent hole with the rest hanging out so that it’s easy to see and remove at the same time i remove my pitot tube cover before flight so that dirt dabbers or other insects do not try to build a nest or cocoon in the vents when it sits in the hanger or out on a ramp when traveling. 

I got some of these, and added "remove before flight" flags.  Can't decide if I like them or not:

https://www.amazon.com/ORXPLUS-TOOLS-Caulk-Sealer-Saver/dp/B07MSGTY7B?th=1

[Will.iam]

Those would work, the beauty of the scott’s towel is i have a roll of them for cleaning the plane anyways. Super cheap at 3 cents per piece.  Don’t have to worry about someone stealing it and although i have never forgot one left in i would think on takeoff the drag of most of the towel hanging out would pull it out of the tube. I don’t have it crammed in the vent just loosely sitting in there as I’m just filling up the space not trying to seal it off. 

[Ragsf15e]

54 minutes ago, Will.iam said:

Those would work, the beauty of the scott’s towel is i have a roll of them for cleaning the plane anyways. Super cheap at 3 cents per piece.  Don’t have to worry about someone stealing it and although i have never forgot one left in i would think on takeoff the drag of most of the towel hanging out would pull it out of the tube. I don’t have it crammed in the vent just loosely sitting in there as I’m just filling up the space not trying to seal it off. 

A true Mooney owner, you know that Scotts towels are 3 cents per piece?! 

[N201MKTurbo]

I would use a drill bit to clean out the vents. It will pull the mud from the mud daubers down and out as you spin it. Just use your fingers to spin it. After you get a hole in the mud, use wet pipe cleaners to clean the last bit of dirt out of the vent. 

[ArtVandelay]

Or something like this would protect it:

[RideOrFly]

Thanks everyone.

[A64Pilot]

You can pull one heck of a vacuum with a fuel pump and the engine keep running, it was a turbine but I have seen a fuel tank collapsed from a clogged vent.

Good catch. Dirt dobbers are bad Ju Ju, they have caused fatal accidents.

‘Many people catch a clogged vent when they refuel, pop the cap and hear it suck in a bunch of air, you have a clogged vent.

[Pinecone]

FYI, a bit expensive for a Mooney CB at 7 cents per, but look nicer than a paper towel hanging below each wing.

Amazon.com: 100 Pieces Pipe Cleaners Chenille Stem, Solid Color Pipe Cleaners Set for Pipe Cleaners DIY Arts Crafts Decorations, Chenille Stems Pipe Cleaners (Red) : Arts, Crafts & Sewing

[LANCECASPER]

29 minutes ago, A64Pilot said:

You can pull one heck of a vacuum with a fuel pump and the engine keep running, it was a turbine but I have seen a fuel tank collapsed from a clogged vent.

Good catch. Dirt dobbers are bad Ju Ju, they have caused fatal accidents.

‘Many people catch a clogged vent when they refuel, pop the cap and hear it suck in a bunch of air, you have a clogged vent.

In 1989 I was flying a Grumman Tiger from Eastern to Western North Dakota and a minute or two after switching fuel tanks from R to L, I heard a strange noise to my left and saw that the wing skins looked like they were bowing in. I switched back to the R since I had plenty of fuel and continued. At my destination I found out that I had something building a nest in the left fuel vent. A small coffee stir straw from the FBO cleaned it out for the return flight.

I haven’t been very diligent in checking this on Mooneys over the years, since they have always been hangared, but I might have to spring for a couple of pipe cleaners.