Long cranks, shuts off at idle after a couple minutes usually

Hi,

The idea that you have to press the throttle indicates a flooding condition. By pressing the throttle to the floor turns off injection. I suspect there is either a problem with a leaking injector or injectors. That would justify the rich fuel mixture as well.

When you checked the fuel pressure, were you experiencing the problem? I'm asking simply because it seems sporadic.

Also, when you pulled the vacuum hose off the fuel pressure regulator, was there any evidence of fuel in the vacuum hose?

By the way, did you mean P0172 above or did you mean 1072. I find nothing under P1072.

Let me know.

Joe

You shouldn't see any fuel from the vacuum hose. That is an indicator that the diaphragm is bad in the regulator. That would result in fuel pressure that is all over the place. Chances are the fuel system is building high pressure, causing the rich fuel mixture, and the added raw fuel is being drawn into the intake via the vacuum hose.

I would recommend replacing the fuel pressure regulator. I feel this is the likely problem.

Here are the directions. The attached pics correlate with the directions.

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2000 GMC Truck C 1500 Truck 2WD V8-5.3L VIN T
Fuel Pressure Regulator Replacement
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pressure Regulator Service and Repair Procedures Fuel Pressure Regulator Replacement
FUEL PRESSURE REGULATOR REPLACEMENT
REMOVAL PROCEDURE

CAUTION: Refer to the Battery Disconnect Caution in Cautions and Notices.

Pic 1

1. Disconnect the negative battery cable.
2. Remove the engine sight shield.
3. Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure.

Pic 2

4. Disconnect the fuel pressure regulator vacuum line.
5. Clean any dirt from the fuel pressure regulator retainer and the surrounding area.
6. Remove the fuel pressure regulator retainer (8).
7. Remove the fuel pressure regulator (9) from the fuel pressure regulator housing.

INSTALLATION PROCEDURE

pic 3

1. Install the backup ring (10) on the fuel pressure regulator (9).
2. Install the new large O-ring (11) on the fuel pressure regulator.
3. Install the regulator filter (12) on the fuel pressure regulator.
4. Install the new small O-ring (13) on the fuel pressure regulator.
5. Lubricate the fuel pressure regulator large O-ring and the small O-ring with clean engine oil.
6. Push the fuel pressure regulator into the regulator housing on the fuel rail.
7. Install a new fuel pressure regulator retainer (8).
8. Connect the fuel pressure regulator vacuum line.

Pic 4

9. Connect the negative battery cable.
10. Tighten the fuel filler cap.
11. Inspect for leaks.
11.1. Turn ON the ignition for 2 seconds.
11.2. Turn OFF the ignition for 10 seconds.
11.3. Turn ON the ignition.
11.4. Inspect for fuel leaks.
12. Install the engine sight shield.

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Try this and let me know the results. Please feel free to ask questions if you have them.

Take care,
Joe

Hi,

Were the misfires on cylinders 2 and 4? It would have been a P0302, P0304, or a random, p0300.

If it was, we need to do a fuel injector balance test. It is possible to misfuel an entire bank of the engine, causing multiple cylinders on the same bank to misfire even though the root cause is a single fuel injector.

Next, is there any chance water from the AC evaporator dripping on the connector can be causing a problem. Check for that.

If you can, switch the o2 sensors between bank 1 and bank 2 to see if it changes the code to the opposite bank.

Also, if there is a restriction in the exhaust, it can cause this code to appear. However, in most cases, you will experience a power loss.

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Not being there makes it difficult. However, (and I can be wrong), I have a feeling it has to do with a faulty injector. Checking fuel injector balance does require a scan tool which can actuate different components. I don't know if you can get your hands on one.

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2000 GMC Truck C 1500 Truck 2WD V8-5.3L VIN T
Fuel Injector Balance Test With Tech 2
Vehicle Powertrain Management Computers and Control Systems Testing and Inspection Component Tests and General Diagnostics Fuel Injector Balance Test Fuel Injector Balance Test With Tech 2
FUEL INJECTOR BALANCE TEST WITH TECH 2
Diagnostic Chart (Part 1 Of 2)

pic 1

Diagnostic Chart (Part 2 Of 2)

pic 2

CIRCUIT DESCRIPTION
The scan tool first energizes the fuel pump and then the injectors for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

TEST DESCRIPTION

CAUTION: Refer to Shop Towel Fuel Leak Caution in Service Precautions.

4. The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
5. The fuel pressure should be within the specified range. If the fuel pressure is not within the specified range, refer to Fuel System Diagnosis. See: Computers and Control Systems > Component Tests and General Diagnostics
6. The fuel pressure should reach a steady value. If the fuel pressure does not reach a steady value, refer to Fuel System Diagnosis. See: Computers and Control Systems > Component Tests and General Diagnostics
7. If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading

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Let me know if this helps or if you have any questions.

Take care,
Joe