Re: Non-vented Fuel Cap Replacement

Mike Steinsland

Hey Mike,
You're probably right.These are my initial thoughts and being busy with the flight controls right now I haven't put a lot of thought into it.
Where did you run yours, on the belly?

On Tue, Mar 16, 2021 at 8:47 AM Mike Dwyer <q200pilot@...> wrote:
Hi Mike.
You'd likely have to stick the tube out at least 2" to get outside the boundary layer.  It would be ugly in my opinion.
Mike Dwyer

On Tue, Mar 16, 2021, 8:02 AM Mike Steinsland <MIKESKUSTOMS@...> wrote:
It doesn't help that I used the wrong terminology...and probably still am... I meant ram air,  not vent.
I was thinking of pressurizing the system through the cap with a tube faired inside a blade like tab facing forward .

On Mon, Mar 15, 2021, 10:43 PM Mike Dwyer, <q200pilot@...> wrote:
I re read your email.  I also have a vent tube like that in my tank filter.  The deal is that without it, and you've got the filter neck full of fuel.  The incoming fuel pressurizes the tank until it finally burps and sprays fuel all over you.  With the vent, the air comes out as the fuel goes in.  I needed it because I have a water filter in 
the tank filler tube and I can easily fill the neck. 

On Mon, Mar 15, 2021, 10:19 PM Mike Steinsland <MIKESKUSTOMS@...> wrote:
Here's the set up on mine. Using a modified plumbing cap. There is a rubber seal at the top of the thread
The inside of the filler neck has a vent tube in it that will go to the rest of the system, I haven't figured out what the original builder was intending but I think I might modify the cap by installing a vented tab into the slot.

On Mon, Mar 15, 2021 at 6:33 PM Corbin via <> wrote:
Agreed.  Honestly, I just want to get the conditional signed off before he has to leave town.  My understanding is the venting/cracking only affects the carb setups.  But I don't want first-hand knowledge of that being incorrect.  I suspect that I have been running with mine venting (cracked), without realizing it, for the last year.


On March 15, 2021 at 5:05 PM, Sam Hoskins <sam.hoskins@...> wrote:


The bottle cap is a shitty design. Besides the cap cracking, the threads can also crack. With a carbureted engine, when that happens it introduces low pressure into your header tank and winds up having an engine that doesn't want to run too well and it first starts acting up at about three or four hundred feet after takeoff. Then you have to Mayday and see if you can limp around the pattern. If you're lucky you will have a passenger along who will later praise your excellent skills and nerves of steel. 

I don't know what happens with a fuel injection engine but if it was me, I wouldn't want to investigate too far. There are a lot of different ways the guys have done fuel caps, not just the one that I use, but mine is pretty simple and you can get parts at any hardware store. There are more elegant methods out there, such as with the Vai-Ez guys may use.

Take care.


On Mon, Mar 15, 2021, 2:17 PM Corbin via <> wrote:
I haven't made Sam's modification using the PVC fitting yet so I am curious if anyone knows the source of this fuel cap that I have.  My A&P found a crack in it during my conditional this week (ready to fly now).





Mike Steinsland

Mike Steinsland

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