1996 z28 with 50K miles on it. car will take three attempts to start if I use 1 new battery and 1 long attempt if I use two new batteries in parrallel. Seems like cold weather starting is perfectly normal. So I am wondering if the engine temp sensor or other sensor devices are bad. I think the car has electronic ignition so we never changed out any rotors or distributor caps. other than the hard startup, the car runs fine. what are the most likely ...should I replace the engine temp, air inlet sensors? no check engine light . only light is the coolant level light. Thanks for any info. I have an ODBC analyzer and there are no codes. charge voltage is 14.5V. we use premium gas in the car.

 

Fuel pump is dying or the FPR is shot. Do a search around here for tips on how to test each. THere are at least 100 posts on each device.

Oh and welcome to the forums.

Massey

 

have you done a fuel pressure test?

 

I'll check the fuel pump since you folks are indicating it is the most likely.....thanks for the lead

I thought it would be more of an temp sensor thing since it cranks up fine in cold weather (block sensor, intake sensor, etc), so I'm glad I asked since I would have been chasing my tail.

 

OK, did a search on the forum, once I got past the dozen or so threads that said do a search on the forum, I found this fuel pressure related test proceedure. I'll try it to night.

Document ID# 724504
2002 Chevrolet Camaro
Fuel System Diagnosis

System Description

When you turn ON the ignition switch, the control module enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

The fuel tank stores the fuel supply. The electric fuel pump supplies fuel through an in-line fuel filter to the fuel injection system. The pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator maintains the correct fuel pressure to the fuel injection system. A separate pipe returns unused fuel to the fuel tank.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step verifies that the fuel pump is operating.

This step tests for an internal fuel leak. If the fuel pressure decreases during this test, an internal loss of pressure is indicated.

This step tests the fuel pressure regulator. The fuel pressure regulator is controlled by engine vacuum. With engine vacuum applied, the pressure should decrease by the specified value.

This step inspects the fuel pressure regulator for a fuel leak from the vacuum port. If fuel leaks from the vacuum port of the fuel pressure regulator while the fuel pump is commanded ON, replace the fuel pressure regulator.

This step tests for a loss of fuel pressure between the fuel pump and the shut-off adapter on the fuel feed pipe.

This step tests for a leaking fuel injector, or fuel pressure regulator. If the fuel pressure remains constant during this test, the fuel injectors are not leaking fuel.

This step tests for a restricted fuel return pipe. If the fuel pressure is within the specified values, a restriction in the fuel return pipe is indicated.

This step determines if the fuel pressure regulator, or the fuel pump, is the cause of the low fuel pressure. If the pressure rises above the specified value, the fuel pump is OK.

This step verifies that a circuit condition is not the cause of a fuel pressure concern. Inspect all fuel pump electrical circuits thoroughly.

Step

Action

Value

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2


Important

Inspect the fuel system for damage, or external leaks before proceeding with this diagnostic.

Turn ON the ignition, with the engine OFF.
Command the fuel pump ON with a scan tool.
Does the fuel pump operate?

--

Go to Step 3

Go to Fuel Pump Electrical Circuit Diagnosis

3


Important

Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic test.

Turn OFF the ignition.
Turn OFF all accessories.
Install the Fuel Pressure Gage. Refer to Fuel Pressure Gage Installation and Removal .
Turn ON the ignition, with the engine OFF.

Important

The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
DO NOT start the engine.
Command the fuel pump ON with a scan tool.
Observe the fuel pressure gage with the fuel pump commanded ON.
Is the fuel pressure within the specified value?

334-375 kPa (48-54 psi)

Go to Step 4

Go to Step 12

4


Important

The fuel pressure may vary slightly if the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

Monitor the fuel pressure gage for 1 minute.

Does the fuel pressure decrease by more than the specified value?

34 kPa (5 psi)

Go to Step 9

Go to Step 5

5

Relieve the fuel pressure to the first specified value.
Monitor the fuel pressure gage for 5 minutes.
Does the fuel pressure decrease by more than the second specified value?

69 kPa (10 psi)

14 kPa (2 psi)

Go to Step 24

Go to Step 6

6

Turn OFF the ignition for 15 seconds.
Turn ON the ignition, with the engine OFF.
Monitor the fuel pressure gage.
Start the engine.
Does the fuel pressure decrease by the specified value after the engine starts?

21-69 kPa (3-10 psi)

Go to Step 7

Go to Step 8

7

Operate the vehicle within the conditions of the customer's concern.
Monitor the fuel related parameters with a scan tool.
Do any of the scan tool parameters indicate a lean condition?

--

Go to Step 17

Go to Symptoms - Engine Controls

8

Disconnect the vacuum hose from the fuel pressure regulator.
Monitor the fuel pressure gage.
Idle the engine.
Apply 12-14 inches of vacuum to the fuel pressure regulator with a hand held vacuum pump.
Does the fuel pressure decrease by the specified value when the vacuum is applied?

21-69 kPa (3-10 psi)

Go to Step 21

Go to Step 23

9

Turn OFF the ignition.
Remove the vacuum hose from the fuel pressure regulator.
Turn ON the ignition, with the engine OFF.
Command the fuel pump ON with a scan tool.
Inspect for a fuel leak from the vacuum port of the fuel pressure regulator.
Is the fuel pressure regulator leaking fuel?

--

Go to Step 23

Go to Step 10

10

Turn OFF the ignition.
Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure .
Disconnect the fuel feed hose and the fuel return hose from the fuel rail pipes. Refer to Quick Connect Fitting(s) Service (Metal Collar) .
Install the J 37287 Fuel Pipe Shut-off Adapters between the fuel pipe between the fuel hoses and the fuel rail pipes.
Open the valves on the shut-off adapters on the fuel pipe.
Turn ON the ignition, with the engine OFF.
Command the fuel pump ON with a scan tool.
Bleed the air from the fuel pressure gage.
Command the fuel pump ON and then OFF with a scan tool.
Close the shut-off valve on the fuel feed pipe.
Monitor the fuel pressure gage for 1 minute.
Does the fuel pressure remain constant?

--

Go to Step 19

Go to Step 11

11

Turn OFF the ignition.
Open the shut-off valve on the fuel feed pipe.
Turn ON the ignition, with the engine.
Command the fuel pump ON and then OFF with a scan tool.
Close the shut-off valve on the fuel return pipe.
Monitor the fuel pressure gage for 1 minute.
Does the fuel pressure remain constant?

--

Go to Step 23

Go to Step 20

12

Is the fuel pressure more than the specified value?

375 kPa (54 psi)

Go to Step 14

Go to Step 13

13

Is the fuel pressure more than the specified value?

0 kPa (0 psi)

Go to Step 16

Go to Step 17

14

Turn OFF the ignition.
Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure .
Disconnect the fuel return hose from the fuel rail pipe. Refer to Quick Connect Fitting(s) Service (Metal Collar) .
Attach a length of a flexible fuel hose to the fuel rail outlet passage.
Place the open end of the flexible fuel hose into an approved gasoline container.
Turn ON the ignition, with the engine OFF.
Monitor the fuel pressure gage with the fuel pump operating.
Is the fuel pressure within the specified value?

334-375 kPa (48-54 psi)

Go to Step 22

Go to Step 15

15

Inspect the fuel rail return pipe and the fuel rail outlet passage for a restriction.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 23

16

Turn OFF the ignition OFF.
Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure .
Disconnect the fuel return hose from the fuel rail pipe. Refer to Quick Connect Fitting(s) Service (Metal Collar) .
Install the J 37287 between the fuel return pipe and the fuel rail.
Open the valve in the fuel pipe shut-off adapter.
Turn ON the ignition, with the engine OFF.
Bleed the air from the fuel system.
Monitor the fuel pressure gage.

Notice

DO NOT allow the fuel pressure to exceed 517 kPa (75 psi). Excessive pressure may damage the fuel system.

Slowly close the valve in the fuel return pipe shut-off adaptor.
Command the fuel pump ON with a scan tool.
Does the fuel pressure increase to more than the specified value?

375 kPa (54 psi)

Go to Step 23

Go to Step 17

17

Inspect the following components for a restriction:

The fuel filter
The fuel feed pipe
Did you find and correct the condition?

--

Go to Step 25

Go to Step 18

18

Inspect the harness connectors and the ground circuits of the fuel pump for poor connections. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

19

Remove the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
Inspect the following items:
The flexible hose of the fuel pump for damage
The harness connectors on the in-tank fuel pump for poor connections
The fuel strainer for a restriction
The fuel tank for contamination
Did you find and correct the condition?

--

Go to Step 25

Go to Step 24

20

Turn OFF the ignition.
Raise the fuel rail without removing the fuel lines. Refer to Fuel Rail Assembly Replacement .
Turn ON the ignition, with the engine OFF.
Command the fuel pump ON with a scan tool.
Locate and replace the leaking fuel injector. Refer to Fuel Injector Replacement .
Did you complete the replacement?

--

Go to Step 25

--

21

Repair the vacuum source to the fuel pressure regulator.

Did you complete the repair?

--

Go to Step 25

--

22

Locate and repair the restricted fuel return pipe.

Did you complete the repair?

--

Go to Step 25

--

23


Important

Before replacing the fuel pressure regulator, inspect for a missing or for a damaged O-ring seal.

Replace the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement .

Did you complete the replacement?

--

Go to Step 25

--

24

Replace the fuel pump. Refer to Fuel Sender Assembly Replacement .

Did you complete the replacement?

--

Go to Step 25

--

25

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3

Document ID# 724504
2002 Chevrolet Camaro
__________________

 

wow thats some serious info right there

 

Liberty, is that you?

 

did the fuel pressure check as per the detailed bulletin. got 51 PSI with engine off, 48 psi 1 minute after pump is off, and 46 PSI 5 minutes after pump is off. So, this would suggest that the pump and regulator are OK.

any other recommendations to check out?

reminder, the problem is the car has a very long key hold to get started, doesn't rip roar with key turn, instead it winds up and stays in windup mode for about 3 seconds, but does start at the end of a long key hold.

The starter related components are new, and so is the battery.

 

mine will start hard once in a while but i belive thats because its rich at first idle. if i touch the throttle a tad its starts right up. in effect giving it more air. has the thottle body ever been cleaned? and if you want to test your temp sensors heres the ohm to temp readings. number 11, shbox is good. 4th Gen LT1 F-Body Tech Aids

 

ok, thanks, will check into those items....