First of all the 1500 Burbans (GMT800 platform) were all new in 2000, so you have the 5.3 liter engine. I hesitate stating that the pressure regulator is for sure your problem, but it is the most probable place to start. Have you done any pressure checks? If there is doubt in regards to my "qualifications" - well, I am technical. I graduated from Southern Illinois Universtity with an Auto Tech degree, wrenched at a dealer prior to hiring on with GM, so yes I know a "little bit" about GM products.
As I mentioned before it is hard to diagnose a car over the internet, phone, etc. Please see what I posted below, if you can get a gage on the fuel system it will help save you some $$$.
When you turn ON the ignition switch, the powertrain control module (PCM) turns ON the in-tank fuel pump. The in-tank fuel pump remains ON as long as the engine is cranking or running and the PCM receives reference pulses. If there are no reference pulses, the PCM turns the in-tank fuel pump OFF 2 seconds after the ignition switch is turned ON or 2 seconds after the engine stops running.
The electric fuel pump attaches to the fuel sender assembly inside the fuel tank . The in-tank fuel pump supplies fuel through an in-pipe fuel filter to the fuel rail assembly. The fuel pump provides fuel at a pressure above the pressure needed by the fuel injectors. A fuel pressure regulator, attached to the fuel rail, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel returns to the fuel tank by a separate fuel return pipe.
When the ignition switch is ON and the fuel pump is running, the fuel pressure indicated by the fuel pressure gauge should read 379-427 kPa (55-62 psi). The spring pressure inside the fuel pressure regulator controls the fuel pressure.
A fuel system that drops more than 34 kPa (5 psi) in 10 minutes has a leak in one or more of the following areas:
- The fuel pump check valve
- The fuel pump flex pipe
- The valve or valve seat within the fuel pressure regulator
- The fuel injectors
A fuel system that drops more than 14 kPa (2 psi) in 10 minutes after being relieved to 69 kPa (10 psi) indicates a leaking fuel pump check valve.
Fuel pressure that drops-off during acceleration, cruise, or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensorss will stop toggling. The heated oxygen sensor output voltages will drop below 300 mV. The fuel injector pulse width will increase.
Hope this helps!
Thanks - MIMC