Actron KAL2535 - Manual (Page 4)

FUEL INJECTION SYSTEMS - GENERAL INFORMATION
Automotive fuel systems and access points are so varied that it is not possible to list all of the test adapter applications.
Always consult a reliable shop manual, or consult the car manufacturer for the recommended test procedure and
connections.
There are two basic types of automotive fuel injection systems:
1. Port Fuel Injection (PFI) - Separate fuel injectors supply fuel to each cylinder.
2. Throttle Body Injection (TBI) – Fuel is injected from a point on the intake manifold above the throttle plate.
• Both systems have a supply side, which provides fuel for the injectors, and a return side, which sends excess fuel
back to the fuel tank.
There are three basic ways to check fuel system pressure:
1. Many domestic cars with PFI systems are equipped with a test port. Connect the proper test adapter to the Test
Gauge, couple the adapter to the test port, and perform the test.
2. On some systems an end-of-hose connection is necessary. Some PFI systems have a flexible hose connection. For
this type of system, connect a single barb fitting with a hose clamp to perform the test. Other systems have a fuel bolt
or banjo type fitting as an access point.
3. The third method of fuel pressure testing is in-line connecting. This method requires separating the fuel line and
installing the Test Gauge and adapters in series.
• Most manufacturers require that you relieve the fuel pressure before connecting to or disconnecting from the fuel
system. To relieve the fuel pressure, it may be necessary to disconnect or disable the fuel pump. Some models may
have two fuel pumps, and both must be disabled. After the fuel pump(s) are disabled, run the engine until it stalls,
then try to restart it for three to five seconds. When the fuel system has been drained of fuel it is ready for testing.
Connect the proper test adapters and the Test Gauge, reconnect the fuel pump and perform the tests. When the tests
are finished, repeat the procedure to relieve the fuel pressure before removing the Test Gauge.
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