I am working hard to get the plane in shape to attend the Open Hangar Day at Zenith on the 21st, but am having a problem venting the fuel tanks.  With the fuel caps provided by Zenith, the left tank flows much faster than the right.  At Zenith's suggestion, I drilled a hole in the filler neck on the right side, but nothing changed.

I then borrowed a cap from a friend's Vagabond and put it on the right tank.  I had some success, so I bought 2 caps from Wag Aero, that have a copper tube coming out of the top of the cap and pointing forward, roughly 90 degrees.  This mirrored the one from the Vagabond.  Unfortunately, I still have the same problem, the right won't flow as fast, to the tune of about a 3 gal. difference showing up pretty quickly?

Next, I put the Vagabond cap back on the right and kept the new vented one on the pilot side.  We can see fuel vapor coming from that cap on the pilot side, but the problem still exists?  Any ideas out there?

And, we did extensive fuel flow testing of all the hoses and had no issues.  We had good flow on both tanks.  The problem seems to be in the venting.

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I'm not sure if this is any help but I experience the same sort of unequal fuel flow issue with my CH-701; the left tank drains faster than the right tank.  I have found the imbalance occurs until about the halfway point in the tanks and then the level generally equalizes.  Additionally, I have ground verified that with one tank empty, the other tank continues to flow fuel normally.  Of course, since this is a Canadian plane I have 3/8" aluminum fuel lines and AN fittings throughout most of my fuel system so I may have a more stable fuel flow than the stock rubber lines.  The WAG fuel caps do look interesting though and I have been thinking of trying them.

Doug M

CH-701 from scratch

NW Ontario, Canada


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