Problem with Fuel flow!!!
I am refurbishing a Hawker Hunter for a friend and have solved most of the issues that were wrongly done by original builder. Fuel system comprises a BVM UAT, followed main tank then 2 saddle tanks in parallel coupled with 1 vent line exiting from bottom of fuselage.
Last Saturday, we encountered a new issue. while filling up the tanks, system seemed over pressured.
In addition when i tried to purge the fuel system to free the bubbles from filter, the pump worked erratically and could not cope....
to rule out a problem with the fuel pump, i fed the input directly from the Fuel jug, and all seemed ok as pump was running at various speeds without any hiccup
Furthermore, after emptying the saddle tanks the draw from main tank seemed fine.
Problem is that saddle tanks have been glued by initial builder and stoppers are not accessible. vent lines are T'ed with 4mm clear tube and there is only 1
4 mm line attached to a short 3 mm brass tube exiting bottom of fuse.
Would appreciate ideas on how to solve this problem trying to avoid any damage to the airframe.