----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Bill, Strange things are happening. The wing tanks are hooked together with a cross feed line ( no valves) so there should always be aprox equal amounts of fuel in the wing tanks. The header tank gravity feeds the Carb......and, as you pointed out, excess fuel flows back to the wing tanks. ( some versions to one tank, some versions to both tanks ( but they are hooked together, so no problem)). So why did your airplane use left wing tank fuel, and header tank fuel ????? and the right tank full ?? you ask, and rightly so. Several potential minor problems. Faulty. loose gaskets on the wing tank caps allow diferential pressure/vacuum on the tanks as air flows over the caps...; if the plane is not rigged properly ( ball in the center when straight and level), then air flow over the wings will be different, and does affect the pressure /vacuum on the caps/tanks; fuel pump only partially working ( right tank still full - header tank dropping) due to a bad fuel pump ---or most likely the fuel pump top cap was not properly re-tightened after the last annual.....and the pump is sucking some air as it tries to suck up fuel from the lower level tanks. Replace the wing tank gaskets, and adjust the tank cap clips so they are tight. Also check the caps for vent holes. Either both should have vent holes or neither should have holes..depending on s/n and if they have holes they must be pointed forward into the air stream. Some models do not have cap vents, utilizing the vent from the header tank to equalize the entire system. There is an AD 81-07-06, I think, requiring the checking of fuel pump sump for water and corrosion and replacement of the screen, gaskets on every annual. Often an owner or mechanic uses the old gaskets, and only gently tightens the small bolt holding the cap on the fuel pump......allowing air to be sucked in around the old gasket instead of sucking up gasoline. The air leak may be small and also may be affected by air temperature, so it may be intermittent...OR... the fuel pump is indeed failing, and needs to be replaced... Have your mechanic check the gasket and torque the bolt to the proper values....(given in the AD), then re- run the engine to assure the header tank stays filled at all times.( about 1 ' below the top of the tank). Then if the "Ball" is out of center, showing the airplane is flying along in a SKID, first check to make sure the nose wheel is properly aligned ( adjustable by the push rod). Pull the aitplane forward about ten feet in a straight line. Now check aeliron position. Do they flair with the trailing edge of the wings, and do the rudders flair with the vertical stabilizers ??? If both align properly, fine. If they dont align properly, then re-rig the airplane controls. Then re-center the aelirons, and have a look at the nose wheel. Off to one side ???? it acts like a rudder if not properly aligned.... adjust the length of the push rod to the nose wheel to make it centered. An off center nose wheel will cause the Coupe to skid and kills about 10 MPH airspeed, depending just how far off it is....... Have fun - Fly Safe Harry Francis Blacksburg, VA. N-93530 s/n 853 ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm
<<attachment: winmail.dat>>
