Fuel Pump Electrical Circuit Diagnosis. Chevrolet Lumina APV 1996

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1996 🢒 Lumina APV 🢒 Engine 🢒 Engine Controls - 3.4L (VIN E) 🢒 Fuel Pump Electrical Circuit Diagnosis

Refer to

Fuel Pump Control

Engine Controls Components
Sensors
Fuel Injector Control
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
.

When the ignition switch is first turned ON, the PCM energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain ON as long as the engine is running or cranking and the PCM is receiving reference pulses. If no reference pulses are present, the PCM de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON or the engine is stopped.

The fuel pump delivers fuel to the fuel rail and injectors, then to the fuel pressure regulator. The fuel pressure regulator, a vacuum sensitive device, controls fuel pressure by allowing excess fuel to be returned to the fuel tank. With the engine stopped, the fuel pump can be turned ON by using a fused jumper to apply B+ to the fuel pump test lead in the engine compartment.

Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following items:

•	Poor connection or damaged harness.

•	Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Test Description

Number(s) below refer to the Step number(s) on the Diagnostic Chart:

diagnosis.

Verifies that the fuel pump feed circuit is OK between the fuel pump relay and the fuel pump, and that the fuel pump can deliver adequate pressure to the fuel rail.

Ensures that the fuel pump relay driver circuit and the PCM are capable of controlling the fuel pump relay.

Checks the fuel pump driver circuit for a short to ground.

Checks the fuel pump driver circuit for an open.

Checks the fuel pump feed circuit between the fuel pump relay and the fuel pump. Also checks the fuel pump ground circuit.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

Fuel System Electrical Test

Step

Action

Value(s)

Yes

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn OFF the ignition switch.
Connect a fuel pressure gage to the fitting on the fuel rail.
Remove the fuel pump relay.
Connect a fused jumper between the B+ feed and the fuel pump feed in the fuel pump relay connector (Cavities 87 and 30).
Note the fuel pressure gage.

Is proper fuel pressure indicated?

284-325 kPa (41-47 psi)

Go to Step 3

Go to Step 9

Disconnect the fused jumper.
Leave the fuel pump relay disconnected.
Connect a J 35616-200 test light between cavities 85 and 86 in the fuel pump relay connector.
Observe the test light while turning ON the ignition.

Did the test light turn ON for approximately 2 seconds?

Go to Step 4

Go to Step 5

Check for poor terminal connections in the relay connector.
If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 23

Leave the relay disconnected.
Connect the test light between cavities 85 and 87 in the relay connector.

Is the test light ON?

Go to Step 6

Go to Step 20

Leave the relay disconnected.
Disconnect the PCM.
Connect the test light to B+.
Probe the fuel pump ignition feed circuit (from the PCM).

Is the test light ON?

Go to Step 19

Go to Step 7

Check for an open in the fuel pump ignition feed circuit (from the PCM).
If a problem is found, replace terminal as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 8

Check for poor terminal connections at the PCM.
If a problem is found, replace terminal(s) as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 25

Is the fuel pump fuse blown?

Go to Step 10

Go to Step 12

Leave the relay disconnected.
Remove the fuel pump fuse.
Probe cavity 87 with the test light connected to B+.

Is the test light ON?

Go to Step 21

Go to Step 11

Leave the relay disconnected.
Raise the vehicle.
Disconnect the modular fuel sender electrical connector at the fuel tank.
Lower the vehicle.
Probe cavity 30 in the relay connector with a test light to B+.

Is the test light ON?

Go to Step 22

Go to Step 24

•	Leave the relay disconnected.

Connect a fused jumper between B+ and the fuel pump feed circuit (cavity 30).

Is proper fuel pressure indicated?

284-325 kPa (41-47 psi)

Go to Step 18

Go to Step 13

•	Leave the relay disconnected.

•	Connect a fused jumper between B+ and cavity 30 in the relay connector.

•	Raise the vehicle.

•	Disconnect the fuel pump harness connector.

•	Connect the test light between fuel pump harness terminals A and C.

Is the test light ON?

Go to Step 14

Go to Step 15

•	Check for poor terminal connections in the fuel pump connector.

•	If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 24

Connect the test light between terminal C in the fuel pump harness connector and chassis ground.

Is the test light ON?

Go to Step 16

Go to Step 17

Locate and repair open in the fuel pump ground circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair open in the fuel pump feed circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair the following circuit condition(s):

•	Open in the B+ feed to the fuel pump relay

•	Poor terminal connection in the relay connector.

•	Poor terminal connection in the fuse block.

Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair the short to ground in the fuel pump relay PCM feed circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair open in the ground circuit to the fuel pump relay. Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair the short to ground in the B+ feed circuit to the relay. Refer to Repair Procedures in Electrical Diagnosis.
Replace the fuel pump fuse.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Locate and repair the short to ground in the fuel pump feed circuit (CKT 120). Refer to Repair Procedures in Electrical Diagnosis.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Replace the fuel pump relay.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Replace the fuel pump.

Is action complete?

Go to Powertrain On Board Diagnostic (OBD) System Check

Replace the PCM.