Tech Tips

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Fuel System

Fuel Injection Do's and Don'ts

• Do follow vehicle manufacturers' specific safety, trouble shooting and service recommendations.

• Do replace fuel filters and oxygen sensors (maintenance items) on a periodic basis as specified by the vehicle manufacturer.  If the vehicle is driven in adverse conditions (dirty roads/poor fuel quality) change more frequently.  Always observe that fuel flow follows directional arrow on the fuel filter.

• Do begin engine management system diagnosis by checking engine basics such as timing, dwell, charging voltage, compression, and ignition components before condemning fuel system components.

• Do check for loose or cracked vacuum hoses which can cause a lean mixture condition.  Re-use of old injector seals can also admit "false-air" to the engine; always replace injector seals during injector servicing.

• Do check/reset the fuel mixture setting after fuel system component replacement or servicing.

• Do clean fuel line connections before opening the system.  Always be aware of high system pressure/cover connections when opening the fuel system.  Remember that residual fuel may be discharged suddenly any time after connections are opened.

• Do use only the replacement parts intended for the specific vehicle application

• Don't disable any safety mechanism that may be designed into the engine management system.

• Don't re-use copper sealing rings or rubber seals (as used with port injectors and pressure regulators).  Re-use may result in dangerous fuel leaks or entry of unmeasured air into the engine.

• Don't spray injectors into open air when testing the vehicle-finely atomized fuel spray is extremely flammable and unhealthy to breathe.

• Don't apply battery voltage directly to electronic port injectors to test them.

• Don't disconnect or attach the wiring harness plug to the vehicle ECU with the ignition on.  Detach ECU plug before electric welding on vehicle.

• Don't interchange K/KE Jetronic fuel distributor control or pressure regulator plungers-they are matched to the fuel distributor body.  Never allow the control plunger to fall from the fuel distributor during service.

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