The fuel injector is an electro-mechanical device which meters, atomizes and directs fuel into the intake manifold based on signals from the ECU driver circuit(s). All Toyota engines used in the U.S.A. position the injectors, one per cylinder, directly behind the intake valve. The injectors are installed with an insulator/seal on the manifold end to isolate the injector from heat and to prevent an atmospheric pressure leak into the manifold. The fuel delivery pipe serves to secure the injector in place. Fuel is sealed on the delivery pipe end by an O-ring and grommet.
To reduce the possibility of vapor lock, which tends to occur during high temperature operation, the 3S-GTE and 2TZ-FE engines use a side feed injector. This type of injector seals with an upper and lower O-ring. O-rings and insulators should always be replaced when injectors are removed; they should never be re-used.
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