REFLECTOR: Unbalanced fuel flow in flight

[Jerry Brainard]

As I recall, the most likely cause is the fuel cap on the left side is not
sealing well enough.  When this condition exists, the low pressure over the
strake lowers the pressure in the tank and fuel does not flow until you have
the fuel levels different enough to overcome the pressure difference.  The
usual solution is to inspect the receiver and if nothing is contaminating
the surface, adjust the cap to clamp more firmly and add a little fuel lube
to the O-ring.

Jerry Brainard
N202VB - XLRG in process

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Richard J. Gentil
Sent: Sunday, March 13, 2011 8:27 AM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Unbalanced fuel flow in flight

Friday I completed my second test flight.  I found that all the fuel drained
from the right side and none from the left while on the one hour flight. (I
actually cut the flight short due to this.)

When I landed I verified with my fuel stick that all the fuel did co e from
the right tank. 

For troubleshooting: 

1) I removed the line from the left tank to the sump tank and verified that
fuel did flow freely from the left tank. 

2) Removed the vent line from the left tank and tested the line in the
direction of the left tank and in the direction to the vent/overflow block
at the top of my firewall using compressed air. 

3) I checked the check valve for the air for correct operation in both
directions and verified it was installed in the correct direction for air to
enter and that fuel would not vent into the cabin. 

4) Verified the overflow line was clear by using compressed air. 

I know the picture is hard to follow but this is the fuel system: