9.28.
Servicing Gasoline Fuel-injection Systems
When a car-engine, equipped with any type of gasoline fuel injection system, experiences a problem, first it is to be ascertained that the trouble is caused by the injection system and not
the engine itself. Normally not all installations of the same type of fuel-injection system are identical in operation or appearance. Therefore one should always refer to the manufacturer’s service manual while attending troubleshooting or servicing a fuel-injection system.
Before attempting to check out or service the system using recommended tools and instruments, it is necessary to make a complete and through visual inspection. The leads from the warm-up regulator and auxiliary-air devices are to be un-plugged first. This prevents the heating elements from overheating these parts.
Two major problems to be looked for when inspecting gasoline fuel-injection system are fuel leaks and air leaks. Either of these can cause driveability problems, and possibly engine damage and excessive emissions.
Diagnostic procedures are supplied in different forms by different manufacturers. Many late-model cars have built in or “on-board” electronic self-diagnostic systems. When a fault occurs, the system stores a number of codes for the fault in its memory. Either a check engine light comes on or the electronic system gives the driver verbal warning that something is wrong. Then, when the mechanic activates the diagnostic system, the number code for the fault appears on the instrument panel. Referring to the manufacturer’s service manual, the mechanic finds the code number which identifies the cause of the fault.
A trouble-diagnosis chart is available for the Bosch K-type continuous fuel-injection system. The chart lists the most frequent complaints and their possible causes and the checks or corrections to be made. Many of the corrections are self-explanatory and can be performed quickly and easily. However, others require use of testers. In this reagard manufacturer’s service manual for the car modal is to be referred.
A trouble diagnosis chart is also available for the Bosch L-type electronic fuel-injection system. The system can be checked with a voltmeter, ohmmeter, pressure gauge, and basic hand tools by following the step in the manufacturer’s service manual. As in the D-type system, the electrical measurements are made at the end of the wiring harness after it is removed from the ECU. However, some tests may be made at the terminals on the individual components. As with other electronic fuel-injection systems, most of the components cannot be repaired. Any component including ECU unit is found to be defective must be replaced.
