All of the Toyota trucks covered by this information are equipped with Sequential Fuel Injection (SFI). Sequential Fuel Injection (SFI) is the activating of the fuel injectors according to the engine firing order and is an accurate method of regulating multi-port injection. In this system, the injectors are controlled individually. Each cylinder receives one charge of fuel, every two revolutions, just before the intake valve opens. Mixture adjustments can be made almost simultaneously between the firing of one injector and the next. A camshaft sensor signals the ECM when the No. 1 cylinder is on the compression stroke.
The following precautions should be followed when working on Toyota's SFI system.
Any Diagnostic Trouble Code retained by the ECM will be erased when the negative battery terminal is disconnected. Use a scan tool to scan for and retrieve trouble codes before disconnecting the negative battery cable.
Disconnect the negative battery cable before beginning work on the SFI system.
Do NOT smoke or allow open flame nearby when working on the fuel system.
Keep gasoline away from rubber parts.
After repair work, check that the ignition coil terminals and all other ignition system lines are reconnected securely.
On sequentially injected fuel injected engines, it is most important that the injector connectors be installed on the proper injector. Always identify and tag the injector connectors before removal. On any connector, release the lock and pull out the connector, not on the wires.
The entire system depends on the engine being air-tight. If the engine oil dipstick, oil filler cap, PCV valve hose or other component is loose, the engine may run poorly. Similarly, if the gasket between the throttle body and intake manifold is deteriorated or loose, the resulting vacuum leak will cause the engine to run poorly.
Before removing SFI system wiring connectors, terminals, etc., turn the ignition switch to the
position. It may also be necessary to disconnect the battery negative terminal.