engine primer. Then, it flows downstream to the fuel pumps.  Typically, one electric and one engine-driven fuel pump are  arranged in parallel. They draw the fuel from the tank(s)  and deliver it to the carburetor. The two pumps provide  redundancy. The engine-driven fuel pump acts as the primary  pump. The electric pump can supply fuel should the other fail.  The electric pump also supplies fuel pressure while starting  and is used to prevent vapor lock during flight at high altitude.  Some high-wing, high-performance, single-engine general  aviation aircraft are equipped with a fuel system that  features fuel injection rather than a carburetor. It combines  gravity flow with the use of a fuel pump(s). The Teledyne- Continental system is an example.  [Figure 14-14] NOTE: Fuel injection systems spray pressurized fuel into the  engine intake or directly into the cylinders. Fuel without any  air mixed in is required to provide a measured, continuous  spray and smooth engine operation.  Fuel pressurized by an engine-driven pump is metered as a  function of engine rpm on the Teledyne-Continental system.  It is first delivered from the fuel tanks by gravity to two  smaller accumulator or reservoir tanks. These tanks, one  for each wing tank, consolidate the liquid fuel and have a  relatively small airspace. They deliver fuel through a three-  An electric auxiliary fuel pump draws fuel through the  selector valve. It forces the fuel through the strainer, making it available for the primer pump and the engine-driven fuel  pump. This pump is typically used for starting and as a  backup should the engine-driven pump fail. It is controlled  by a switch in the cockpit and does not need to be operating  to allow the engine-driven fuel pump access to the fuel. way selector valve (LEFT, RIGHT, or OFF). The selector  valve also acts simultaneously as a diverter of air that has  been separated out of the fuel in the engine-driven fuel pump  and returned to the valve. It routes the air to the vent space  above the fuel in the selected reservoir tank.  14-11 Figure 14-14.  A Teledyne-Continental fuel system featuring fuel  injection used on high-wing, high-performance single-engine  aircraft. Figure 14-13.  A single reciprocating engine aircraft with fuel tanks  located in wings below the engine uses pumps to draw fuel from the  tanks and deliver it to the engine.  High-Wing Aircraft with Fuel Injection System Fuel supply Pump delivery Right tank  Left tank BOTH LEFT RIGHT OFF Primer Fuel selector valve Strainer Carburetor Electric pump plunger type Engine-driven pump diaphragm type Fuel reservoir  tank Right tank Aft Forward OFF Fuel reservoir  tank  Left tank Aft Forward Engine primer Selector valve Auxiliary fuel pump Engine-driven fuel pump Fuel flow indicator Fuel injection distributor manifold Fuel injection control unit Fuel strainer To intake manifold Vent check valve Vent check valve Vented filler caps