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Hierarchy of likely
fuel injection faults
Disconnect the ECU
Ground pin 20, then pin 21 of the ECU
 | Pump
doesn't run? Either or both relays is/are bad;
stop
and repair |
 | Pump
runs? Pump relay is OK; proceed |
Remove ground from pin 20; leave pin 21
grounded, then ground pin 18
 |
Fuel
injectors do not click? Fuel System relay is bad,
or corrosion in the large round connector;
stop
and repair. |
 | Fuel
injectors click? Proceed
 |
Check
for voltage on pin 5 of the air mass meter connector
 |
No
voltage? System relay is bad;
stop and repair. |
 |
Voltage
OK? System relay is OK:
proceed |
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Reconnect ECU. Connect meter (dc volts, 3
volt scale) across a fuel injector.
Crank engine. 0.3 to 1 volt
indicated, injectors are clicking, pump is running?
 | If
YES TO ALL, the fuel system is working well enough that the engine should at least
start (although
the Air Mass Meter could be bad).
 | If
no voltage, no injector clicks and pump does not run, then something is probably
wrong in the crank sensor circuit. |
 | If
only the pump runs or only the injectors show voltage and click, suspect the
ECU.
 | NOTE: ECU
failures are NOT common; the problem is almost always
something simpler, such as a relay, or corrosion. |
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AND A FINAL NOTE: I once read voltage over and over and
over again at the injectors - the voltage was there, but corrosion in the round
connector prevented any significant current from flowing. SO be sure that
you have current as well as voltage - make sure the injectors click. They
may be hard to distinguish when the engine is running or cranking, but you
should definitely hear them in the pin 18 test.

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