since 1940

Cockpit fuel flow differential on Twin-Engine planes

1. Metered and unmetered fuel pressure out of adjustment (Continental).

2. Manifold gauge out of calibration.

3. Improper size of nozzles in one engine (Continental).

4. (Continental) Leak in mixture control valve which dumps fuel back to pump through mixture control valve. If unmetered fuel pressure (pump pressure) is normal but metered fuel pressure is low or cockpit fuel flow gauge is indicating lean then fuel is bypassing the fuel control unit. To correct, lap mixture control valve.

5. Turbocharger rate controller out of adjustment.

6. Plugged fuel injector nozzle.

7. Dirty fuel screen.

8. Lean or rich fuel injector.

9. Continental makes three different compression springs for their fuel injected engine distributor valves which distribute metered fuel to the individual fuel injectors. Continental flows the injection system at the factory and puts in the spring to supposedly  make each system flow the same.  On twin engine aircraft, the systems can get swapped over the years and the fuel flows show different on the fuel flow indicator between the two engines. A new seal diaphragm and a different spring can bring the two fuel flows together with trial and error. - thank you Dick for this submission!

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