2002 z06 fuel pump issue
#1
03-22-2012, 08:20 PM
2002 z06 fuel pump issue
Hi guys, im new to the forum so first off hello! 
My name is Jake and I have a 2002 Z06 (my pride and joy, I no longer need a girlfriend) 
Its modified with AFR 205's, LG G5X3 cam, LG long tubes, and no cats. Today, a mind boggling issue came up... I took my car to visit a friend at work, I went to get some Taco Bell for lunch and about 200 feet down the road it felt like it was starving for fuel, shaking to and froe violently, almost like it had a cam 2x as big. It then threw the dreaded "reduced engine power" code on the DIC along with "Pull key, wait 10 seconds" and died. It would not re-fire... After finding out the fuel pump wasn't engaging I checked fuses and relays and determined it was a bad pump. We ordered a pump and hoisted it on the lift... I noticed that the passenger side o2 sensor was detached. (i must have ran something over and ripped it loose, it had been this way for a while as the wires were dirty from road debris and the red wire coating was MIA) we put a new pump into the car and tried starting, the fuel pump wasn't making any noise. The test light indicated that the pump was going hot for almost 2 milliseconds then stopping, fuel pressure reading 0psi during cranking. Anyone have any ideas what this could be?
My name is Jake and I have a 2002 Z06 (my pride and joy, I no longer need a girlfriend) Its modified with AFR 205's, LG G5X3 cam, LG long tubes, and no cats. Today, a mind boggling issue came up... I took my car to visit a friend at work, I went to get some Taco Bell for lunch and about 200 feet down the road it felt like it was starving for fuel, shaking to and froe violently, almost like it had a cam 2x as big. It then threw the dreaded "reduced engine power" code on the DIC along with "Pull key, wait 10 seconds" and died. It would not re-fire... After finding out the fuel pump wasn't engaging I checked fuses and relays and determined it was a bad pump. We ordered a pump and hoisted it on the lift... I noticed that the passenger side o2 sensor was detached. (i must have ran something over and ripped it loose, it had been this way for a while as the wires were dirty from road debris and the red wire coating was MIA) we put a new pump into the car and tried starting, the fuel pump wasn't making any noise. The test light indicated that the pump was going hot for almost 2 milliseconds then stopping, fuel pressure reading 0psi during cranking. Anyone have any ideas what this could be?
#2
03-26-2012, 10:34 PM
I believe this comes from the service manual, although I'm not sure which year it covers:
Fuel Pump Electrical Circuit Diagnosis
Circuit Description
When you turn ON the ignition, the powertrain control module (PCM) activates the in-tank fuel pump. The in-tank fuel pump remains ON as long as the following conditions are met:
The engine is cranking or running.
The PCM receives any reference pulses from the ignition system.
If there are not any reference pulses, the PCM turns the in-tank fuel pump OFF after about 2-3 seconds.
The electric fuel pump is attached to the fuel sender assembly inside the left fuel tank. The in-tank fuel pump supplies fuel through a pipe fuel filter, or through the fuel pressure regulator assembly, to the fuel rail. The fuel pump supplies fuel to the siphon jet pump of the right fuel tank. This allows the pump to transfer fuel from the right fuel tank to the left fuel tank. The fuel pump provides fuel at a pressure that is above the pressure needed by the fuel injectors. The fuel pressure regulator, part of the fuel filter, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel returns to the left fuel tank by a separate fuel return pipe.
Diagnostic Aids
Fuel Pump Relay Underhood Electrical Center Terminal Identification
Front of Vehicle
Left Side of Vehicle
Ground
Ignition
Right Side of Vehicle
Fuel Pump Supply
Control
The following conditions may have caused the fuel pump fuse to open:
The fuse was faulty.
There is an intermittent short in the power feed circuit of the fuel pump.
The fuel pump has an internal intermittent condition.
For an intermittent condition, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Command the ON and the OFF states. Repeat the commands as necessary.
This step determines if the condition is located on the coil side, or on the switch side of the circuit.
This step verifies that the powertrain control module is providing voltage to the fuel pump relay.
This step tests for an open in the ground circuit to the fuel pump relay.
This step determines if a voltage is constantly being applied to the fuel pump relay.
This step tests for a grounded supply circuit between the fuel pump relay and the harness connector of the fuel pump.
This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
This step determines if the fuel pump relay is causing the condition. Use the appropriate-size fused jumper wire.
This step tests for an open, or for excess resistance in the supply circuit between the relay and the harness connector of the fuel pump.
Inspect the fuel pump ground circuit thoroughly. Corrosion or a poor connection may cause the fuel pump stop operating.
This step inspects for a poor connection or for corrosion at the fuel pump harness connector which may cause the condition.
Step
Action
Yes
No
Schematic Reference: Fuel Pump and Fuel Tank Pressure Sensor
1
Did you perform the Diagnostic System Check-Engine Controls?
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the fuel pump relay ON and OFF.
Does the fuel pump turn ON and OFF?
Go to Diagnostic Aids
Go to Step 3
3
With a scan tool, command the fuel pump relay ON and OFF.
Do you hear a click if you command the fuel pump relay ON and OFF?
Go to Step 9
Go to Step 4
4
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Important
Refer to Diagnostic Aids for fuel pump relay terminal identification.
Probe the control circuit of the fuel pump relay with a test lamp connected to ground.
With a scan tool, command the fuel pump relay ON and OFF.
Does the test lamp turn ON and OFF?
Go to Step 5
Go to Step 6
5
Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
With a scan tool, command the fuel pump relay ON and OFF.
Does the test lamp turn ON and OFF?
Go to Step 19
Go to Step 22
6
Does the test lamp remain illuminated with each command?
Go to Step 7
Go to Step 8
7
Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 26
8
Test the control circuit of the fuel pump relay for a short to ground, or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 20
9
Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?
Go to Step 10
Go to Step 11
10
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?
Go to Step 21
Go to Step 25
11
Is the fuel pump fuse open?
Go to Step 12
Go to Step 14
12
Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Replace the fuel pump fuse if necessary.
Did you find and correct the condition?
Go to Step 27
Go to Step 13
13
Install all disconnected components.
Install a new fuel pump fuse.
With a scan tool, turn ON the fuel pump.
Is the fuel pump fuse open?
Go to Step 24
Go to Intermittent Conditions
14
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Probe the battery voltage circuit of the fuel pump relay switch with a test lamp connected to ground.
Does the test lamp illuminate?
Go to Step 15
Go to Step 23
15
Connect a 20-amp fused jumper wire between the battery voltage circuit of the relay switch and the supply voltage circuit of the fuel pump.
Does the fuel pump operate?
Go to Step 19
Go to Step 16
16
Test the supply voltage circuit of the fuel pump for an open, or for high resistance between the relay and the fuel pump harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 17
17
Important
Inspect the ground circuit for tightness, for corrosion on terminals, or for damage to the wiring harness.
Test the ground circuit of the fuel pump for an open, or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 18
18
Inspect for poor connections at the harness connector of the fuel pump. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 24
19
Inspect for poor connections at the fuel pump relay. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 25
20
Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 26
21
Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
22
Repair the open ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
23
Repair the battery voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
24
Important
Before replacing the fuel pump, inspect for bad connections at the fuel pump, and within the fuel tank.
Replace the fuel pump. Refer to Fuel Tank Pump Module Replacement .
Replace the fuel pump fuse if necessary.
Did you complete the replacement?
Go to Step 27
--
25
Replace the fuel pump relay.
Did you complete the replacement?
Go to Step 27
--
26
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
Go to Step 27
--
27
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2
Circuit Description
When you turn ON the ignition, the powertrain control module (PCM) activates the in-tank fuel pump. The in-tank fuel pump remains ON as long as the following conditions are met:
The engine is cranking or running.
The PCM receives any reference pulses from the ignition system.
If there are not any reference pulses, the PCM turns the in-tank fuel pump OFF after about 2-3 seconds.
The electric fuel pump is attached to the fuel sender assembly inside the left fuel tank. The in-tank fuel pump supplies fuel through a pipe fuel filter, or through the fuel pressure regulator assembly, to the fuel rail. The fuel pump supplies fuel to the siphon jet pump of the right fuel tank. This allows the pump to transfer fuel from the right fuel tank to the left fuel tank. The fuel pump provides fuel at a pressure that is above the pressure needed by the fuel injectors. The fuel pressure regulator, part of the fuel filter, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel returns to the left fuel tank by a separate fuel return pipe.
Diagnostic Aids
Fuel Pump Relay Underhood Electrical Center Terminal Identification
Front of Vehicle
Left Side of Vehicle
Ground
Ignition
Right Side of Vehicle
Fuel Pump Supply
Control
The following conditions may have caused the fuel pump fuse to open:
The fuse was faulty.
There is an intermittent short in the power feed circuit of the fuel pump.
The fuel pump has an internal intermittent condition.
For an intermittent condition, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Command the ON and the OFF states. Repeat the commands as necessary.
This step determines if the condition is located on the coil side, or on the switch side of the circuit.
This step verifies that the powertrain control module is providing voltage to the fuel pump relay.
This step tests for an open in the ground circuit to the fuel pump relay.
This step determines if a voltage is constantly being applied to the fuel pump relay.
This step tests for a grounded supply circuit between the fuel pump relay and the harness connector of the fuel pump.
This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.
This step determines if the fuel pump relay is causing the condition. Use the appropriate-size fused jumper wire.
This step tests for an open, or for excess resistance in the supply circuit between the relay and the harness connector of the fuel pump.
Inspect the fuel pump ground circuit thoroughly. Corrosion or a poor connection may cause the fuel pump stop operating.
This step inspects for a poor connection or for corrosion at the fuel pump harness connector which may cause the condition.
Step
Action
Yes
No
Schematic Reference: Fuel Pump and Fuel Tank Pressure Sensor
1
Did you perform the Diagnostic System Check-Engine Controls?
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the fuel pump relay ON and OFF.
Does the fuel pump turn ON and OFF?
Go to Diagnostic Aids
Go to Step 3
3
With a scan tool, command the fuel pump relay ON and OFF.
Do you hear a click if you command the fuel pump relay ON and OFF?
Go to Step 9
Go to Step 4
4
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Important
Refer to Diagnostic Aids for fuel pump relay terminal identification.
Probe the control circuit of the fuel pump relay with a test lamp connected to ground.
With a scan tool, command the fuel pump relay ON and OFF.
Does the test lamp turn ON and OFF?
Go to Step 5
Go to Step 6
5
Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
With a scan tool, command the fuel pump relay ON and OFF.
Does the test lamp turn ON and OFF?
Go to Step 19
Go to Step 22
6
Does the test lamp remain illuminated with each command?
Go to Step 7
Go to Step 8
7
Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 26
8
Test the control circuit of the fuel pump relay for a short to ground, or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 20
9
Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?
Go to Step 10
Go to Step 11
10
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Does the fuel pump operate continuously?
Go to Step 21
Go to Step 25
11
Is the fuel pump fuse open?
Go to Step 12
Go to Step 14
12
Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Replace the fuel pump fuse if necessary.
Did you find and correct the condition?
Go to Step 27
Go to Step 13
13
Install all disconnected components.
Install a new fuel pump fuse.
With a scan tool, turn ON the fuel pump.
Is the fuel pump fuse open?
Go to Step 24
Go to Intermittent Conditions
14
Turn OFF the ignition.
Disconnect the fuel pump relay.
Turn ON the ignition, with the engine OFF.
Probe the battery voltage circuit of the fuel pump relay switch with a test lamp connected to ground.
Does the test lamp illuminate?
Go to Step 15
Go to Step 23
15
Connect a 20-amp fused jumper wire between the battery voltage circuit of the relay switch and the supply voltage circuit of the fuel pump.
Does the fuel pump operate?
Go to Step 19
Go to Step 16
16
Test the supply voltage circuit of the fuel pump for an open, or for high resistance between the relay and the fuel pump harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 17
17
Important
Inspect the ground circuit for tightness, for corrosion on terminals, or for damage to the wiring harness.
Test the ground circuit of the fuel pump for an open, or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 18
18
Inspect for poor connections at the harness connector of the fuel pump. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 24
19
Inspect for poor connections at the fuel pump relay. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 25
20
Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 27
Go to Step 26
21
Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
22
Repair the open ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
23
Repair the battery voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 27
--
24
Important
Before replacing the fuel pump, inspect for bad connections at the fuel pump, and within the fuel tank.
Replace the fuel pump. Refer to Fuel Tank Pump Module Replacement .
Replace the fuel pump fuse if necessary.
Did you complete the replacement?
Go to Step 27
--
25
Replace the fuel pump relay.
Did you complete the replacement?
Go to Step 27
--
26
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
Go to Step 27
--
27
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2
#3
03-27-2012, 11:22 AM
Dave, that was an awesome write up. It turned out the old fuel pump is fine.. I got the car in the air so I could get a better look at it. I found out that one of the brackets holding the cra nk position sensor, and the o2 sensor wire harness broke and laid it down on my left header. So I broke out the tools, removed the header and the rest of the exhaust to give my self some room to work and cut out the melted wire mess out, soldered a new harness and ran some new loom. I hooked it up to my tech 2 cleared the engine codes and she is running like a dream now 
hooray
hooray
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