No Start Diagnosis

Injector System Diagnosis- No Start:

DFI Fuel Pump/Injector Circuit:

TEST DESCRIPTION
1. If this procedure is being followed for a "no-start" condition, crank the engine for S seconds to check the distributor reference signal. If a Code E12 does not set, turn the ignition off for 10 seconds and observe the injectors as the ignition is turned back on. If there is no spray, then they are not stuck open. Observe the injectors while cranking the engine.

2. To determine if the injector is being activated electrically, repeat the above procedure with the electrical connector removed. If the injector continues to spray, it is defective and must be replaced. If the injector no longer sprays, the drive circuit of the affected injector must either be shorted to ground or the Electronic Control Module (ECM) is grounding internally.

3. If both injectors spray or if neither injector sprays, it must be determined if the fuel system is operating properly. The fuel pressure gage J-25400-300 should be installed at the fuel line service fitting. Measure the fuel pressure while cranking the engine. If the fuel pressure is not between 9-12 PSI, refer to Fuel System Diagnosis.

4. If the fuel pressure is between 9-12 psi and there was no spray from either injector while cranking, the injector circuit must be checked for proper voltage. If there is voltage at the injector fuses, then the ECM must be faulty because it is failing to ground both injector circuits. If there is no voltage at the fuse, check for voltage at the 15 amp ECM fuse which feeds the injector fuses. If there is voltage here then an open must exist between the fuses on circuit 439. If there is no voltage at the ECM fuse then circuit 3 must be repaired for an open or short to ground.

5. If the fuel pressure is between 9-12 psi and there was fuel spray from both injectors while cranking, then check the injector system to determine if the injectors leak. To check for injector leakage, proceed as follows:

a. Start and run the engine for 10 seconds.
b. Turn the engine off for at least 10 seconds.
c. Turn the ignition on to pressurize the injectors.
d. Visually check for dripping fuel from the bottom of the injector.

If the fuel is dripping, check for damaged "0" rings and if OK, replace the injector. If the fuel does not drip, then the fuel system is OK.

6. If there is spray from only one injector, then there is a malfunction in the injector assembly or in the signal to the injector assembly. The malfunction can be isolated by switching the injector connectors. If the problem remains with the original injector after switching the connector, then the injector is defective. Replace the injector.