Toyota Celica 1986-1993 Repair Guide

Safety Precautions


Safety is the most important factor to adhere to when performing maintenance on the EFI system. Failure to conduct fuel system maintenance and repairs in a safe manner may result in serious personal injury. Maintenance and testing of the vehicle's fuel system components can be accomplished safely and effectively by adhering to the following rules and guidelines.


To avoid the possibility of fire and personal injury, ALWAYS disconnect the negative battery cable unless the repair or test procedure specifically requires that battery voltage be applied.
ALWAYS relieve the fuel system pressure prior to disconnecting any fuel system component (injector, fuel rail, pressure regulator, etc...), fitting or fuel line connection. To relieve pressure wrap a shop rag around the fitting or connection being opened, a slowly open the system. Wait for pressure to relieve itself, then remove the rag and wipe up any spilled fuel. Exercise extreme caution whenever relieving fuel system pressure to avoid exposing skin, face and eyes to fuel spray. Be advised that fuel under pressure may penetrate the skin or any part of the body that it comes in contact with.
ALWAYS place a shop towel or cloth around the fitting or connection prior to loosening to absorb any excess fuel due to spillage. Ensure that all fuel spillage (should it occur) is quickly removed from engine surfaces. Ensure that all fuel soaked cloths or towels are deposited into a suitable waste container.
ALWAYS have a properly charged fire extinguisher in the vicinity of the work area and ALWAYS ensure work areas are adequately ventilated.
Do NOT allow fuel spray or fuel vapors to come in contact with spark or open flame. Remember that smoking and fuel maintenance do NOT mix!
ALWAYS use a backup wrench when loosening and tightening fuel line connection fittings. This will prevent unnecessary stress and torsion to fuel line piping. ALWAYS follow the proper torque specifications.
ALWAYS replace fuel fitting O-rings with new ones. Do NOT substitute fuel hose or equivalent where rigid fuel pipe is called for.


When connecting test equipment (tachometer, timing light, etc.) use the battery as the power source.
ALWAYS ensure that the battery and ignition coil terminals are properly and securely connected.
Handle the spark plug wires carefully. ALWAYS pull by the boots and NEVER on the wires.
During engine compartment cleaning, ALWAYS protect electrical system components from water.
Do NOT strike the oxygen sensor or place stress on the sensor wire. Do NOT allow the oxygen sensor to come in contact with water.
Improper installation of the engine oil dipstick, oil filler cap, pcv valve hoses, etc. may cause the engine to run lean and idle poorly.
Any loose, disconnected or cracked part of the air induction system between the throttle body and the air intake manifold may cause the engine to run lean and idle poorly.
Before disconnecting ECU connectors, terminals, etc., first disconnect the power by turning the ignition switch to the Off position or disconnecting the battery terminals.
When installing the battery, make sure that the proper polarity is observed when connecting the cables.
Handle the EFI system components carefully during removal and installation, especially the ECU. These components are very susceptible to damage if dropped or handled roughly.
Be careful When troubleshooting the EFI system. There are many transistor circuits involved and even the slightest contact between terminals can cause damage.
NEVER open the ECU cover.