Injector Flow Drop Check

Fuel System Diagnosis (Injector Flow Drop Check):

Fuel System Diagnosis (Injector Flow Drop Check) (continued):

Fuel System Diagnosis (Injector Flow Drop Check) (continued):

Engine Controls (Fuel Injectors):

The Injector Flow/Voltage Drop Check compares the fuel pressure drop when each injector is pulsed for a set amount of time. Since each injector is pulsed the same, the fuel pressure drop for each injector should be approximately the same. Suspect fuel injectors can be identified by either too high or too low fuel pressure drop. This check also determines if the voltage drop of the injector is within specification. Injector voltage drop out of specification can cause driveability conditions that are intermittent or that do not show up during an injector flow check. This chart requires J 34730-1A Fuel Pressure Gauge, J 39200 Voltmeter, J 39021 Fuel Injector Tester

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

3. Commanding the fuel pump on for 5 seconds will energize the fuel pump to build fuel pressure. Then selecting individual injectors will allow you to see the fuel pressure drop associated with each injector. If all eight injectors drop some pressure then the circuit is not open. Any injector that drops no pressure has an open in the circuit or a faulty injector.

5. Checking if a fuse was open causing either injectors 2, 3, 5, 8, or 1, 4, 6 and 7 not to operate.

6. Checking if CKT 739 or CKT 1239 is open from the fuse to C127.