Checking Fuel Delivery

CHECKING FUEL DELIVERY






POSSIBLE CAUSES
FUEL PUMP RELAY OUTPUT CIRCUIT OPEN
FUEL PUMP RELAY
FUEL PRESSURE OUT OF SPECIFICATION
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP

Diagnostic Test
1. FUEL PUMP OPERATION





WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE EVEN WITH THE ENGINE OFF. BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRESSURE MUST BE RELEASED.

Turn the ignition on.
With the DRB III, actuate the Fuel Pump Relay.
Listen for fuel pump operation. Stop All Actuations.
Does the Fuel Pump operate?
Yes>> Go To 2
No>> Go To 4

2. FUEL PRESSURE





WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE EVEN WITH THE ENGINE OFF. BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRESSURE MUST BE RELEASED.

Turn the ignition off.
Install a fuel pressure gauge at the engine.
Turn the ignition on.
With the DRB III, actuate the Fuel Pump Relay and observe the fuel pressure gauge.

Note: Fuel pressure specification is 3.7 to 4.2 bar (54 to 61 psi). Stop All Actuations.

Choose a conclusion that best matches your fuel pressure reading.
Below Specification Go To 3
Within Specification Test Complete.
Above Specification Replace the fuel filter/fuel pressure regulator.
Perform Powertrain Verification Test - Ver 3

3. CHECKING FUEL STRAINER

WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE EVEN WITH THE ENGINE OFF. BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRESSURE MUST BE RELEASED.

Turn the ignition off. Remove and inspect the Fuel Strainer.
Is the Fuel Strainer plugged?
Yes>> Replace the Fuel Strainer.
Perform Powertrain Verification Test - Ver 3
No>> Replace the Fuel Pump.
Perform Powertrain Verification Test - Ver 3

4. FUEL PUMP RELAY OUTPUT CIRCUIT OPEN





Turn the ignition off.
Disconnect the Fuel Pump harness connector.

Note: Check connectors-Clean/repair as necessary.

Turn the ignition on.
With the DRB III, actuate the Fuel Pump Relay.
Using a 12-volt test light connected to ground, probe the Fuel Pump Relay
Output circuit at the Fuel Pump harness connector.
Does the test light illuminate brightly?
Yes>> Go To .
No>> Check for an open Fuel Pump fuse in the Relay Control Module. Repair the Fuel Pump Relay Output circuit for an open.
Perform Powertrain Verification Test - Ver 3

5. FUEL PUMP





Note: Check connectors - It is critical that the connector is free from any signs of corrosion or deformities. Clean/repair as necessary.

With the ignition on.
Using a 12-volt test light connected across the Fuel Pump harness connector.
With the DRB III, actuate the Fuel Pump Relay.
Does the test light illuminate brightly?
Yes>> Replace the Fuel Pump.
Perform Powertrain Verification Test - Ver 3
No>> Repair the fuel pump ground circuit for an open.
Perform Powertrain Verification Test - Ver 3