HefLozano88

I wish there was an inline filter. I could rule out things much easier and with much less money spent.

HefLozano88

UPDATE:

No closer to a fix at all. I ran 1 can of the BG fuel treatment through the system. I drove to wedding this weekend, approx 70 miles each way. Both on the way there and the way back I experienced much worse hesitation than I ever have. It was happening more frequently and more severe. We had to stop at home after the wedding then off to grandmas to take the kids, while it sat in the driveway it died twice, and it was slow like it was running out of gas. I bought the gauge to check fuel pressure. I have 50 PSI with key on engine off, and 60 PSI with engine running. It is not throwing any codes out yet. I figured maybe the fuel pressure regulator, but guess what? It is also apparently in the tank with the pump and filter. I have a returnless fuel system. There is only 1 fuel line that goes to the fuel rail. Running the motor with the gauge hooked up I cannot get it to hesitate. I will be driving it tomorrow for some distance to try and get it to do it again so I can see what the pressure is when it hesitating. I'm at a loss of wits now. I don't know what else to check. I don't want to just throw a new $350 fuel pump at it only to find out it still hesitates. Any new ideas would be greatly appreciated. Thanks

trainwreck91

With that kind of mileage it's likely the pump or the filter. Try rock auto.com and see if you can get the pump for a decent price. Don't know how handy you are but it might be something you can tackle yourself.

HefLozano88

Thanks I will check into it. I do all my own work, I used to wrench myself but now I'm an electrician. The way its acting now is like its missing on one or 2 cylinders. almost like the coils are going bad. It only does it after it warms up and has been running for a few miles. once its been doing it for a while it still has good fuel pressure and thats why I am leaning away from the pump. I can do the work no problem, its the spending $350 or more just to find out that its not the pump that I have issues with.

Joe In NY

Sorry havent read the whole thread yet but, our 2002 had bad hesitation, what fixed it was:

New Fuel filter (had the return style fuel system with inline filter)
New Air filter
New Spark Plugs
Throttle body clean
And A real injector clean, hooked the injector cleaning machine up to the feed and return line going to the motor and ran a powerful cleaner through the motor. Ran it at a constant ~2,000 rpm for 30 min till it started sputtering.

It ran FANTASTIC after all that. But about one year later it started to run really rough at idle. Turns out the intake gasket had broken and was leaking really bad. Would barely idle when cold...

HefLozano88

Thanks and I wish it was that easy. I have washed out my K&N air filter, changed the spark plugs, replaced the throttle body, cleaned the MAF sensor, replaced both knock sensors and the wire harness that goes to them, replaced the intake manifold gasket, replaced the valve cover gaskets, replaced all the injector seals, ran a few different fuel system cleaners through it, and also the coolant temp sensor.

The fuel system on the 2004 and newer (at least to 2006) they tried a new system. Returnless, there is only one fuel line that goes to the fuel rail. no return line. No inline fuel filter on the frame rail, instead its in the tank on the pump. No fuel pressure regulator on the fuel rail, instead it is in the tank on the pump. I have 50 PSI with key on engine off, and then have 60 PSI while the truck is running. Once warm and running down the road it starts to hesitate like 1 or more cylinders are not firing. I take the car back home and check the fuel pressure again and it still stays right at 60 PSI, the car with hesitate while sitting there and the pressure never drops. So I don't think it is the pump. It will not throw out any codes either. It hesitates on acceleration but only under a load. It will not do it while sitting in park or neutral, I can throttle the pedal up and down and no hesitation.

in2pro

Hummm only does it under load...
a communication issue with the transmission?
bogs down waiting to down shift or the down shift is delayed?
Throttle position sensor?
Bad info from the O2 system once it goes to closed loop?
clogged cat?

Just some ideas

in2pro

Some info from the manual that might be helpful...

Service Information
2004 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 839324
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Hesitation, Sag, Stumble
Inspection/Tests
Action

DEFINITION: Momentary lack of response as the accelerator is pushed down. Can occur at any vehicle speed. Usually more pronounced when first trying to make the vehicle move, as from a stop. May cause the engine to stall if severe enough.

Preliminary
• Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .

• Search for bulletins.

• Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

Sensor/System
Inspect the manifold absolute pressure (MAP) sensor operation.

Fuel System
• Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .

• Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 ignition coils and 4 fuel injectors not to operate. Inspect the ignition coil circuits and the fuel injector circuits for an intermittent short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Replace the fuse.

• Inspect for the following that may cause the engine to run rich:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

- Water intrusion in the heated oxygen sensor (HO2S) connector

- Engine oil contaminated by fuel

- An evaporative emission (EVAP) canister purge condition

- Incorrect fuel pressure--Refer to Fuel System Diagnosis .

- Leaking fuel injectors--Refer to Fuel System Diagnosis .

- An inaccurate mass air flow (MAF) sensor

- Blockage on the inlet screen of the MAF sensor--Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .

- Vacuum hoses that are split, kinked, or improperly connected

- An air intake duct that is collapsed or restricted--Refer to Air Cleaner Resonator Outlet Duct Replacement .

- An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .

• Inspect for the following conditions that may cause the engine to run lean:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

- Water intrusion in the HO2S connector

- An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage in Engine Exhaust.

- Vacuum leaks

- Incorrect fuel pressure--Refer to Fuel System Diagnosis .

- Restricted fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .

- An inaccurate MAF sensor

- Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

- Vacuum hoses that are split, kinked, or improperly connected

Ignition System
• Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.

• Test for proper ignition voltage output with the J 26792 Spark Tester . Refer to Electronic Ignition (EI) System Diagnosis for the procedure.

• Remove the spark plugs and check for the following:

- Correct heat range

- Wet plugs

- Cracks

- Wear

- Improper gap

- Burned electrodes

- Heavy deposits

Refer to Spark Plug Inspection .

• An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Spark Plug Replacement .

• Determine the cause of the fouling before replacing the spark plugs.

• Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .

• Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .

Engine Cooling System
Inspect the engine thermostat for proper operation and for proper heat range. Refer to Thermostat Diagnosis in Engine Cooling.

Engine Mechanical
Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions:

• A no start

• A start and stall

• Erratic performance

Additional Inspections
Inspect the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical for the procedure. Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.

73shark

Since it just does it under load, I suspect the problem is ignition related. That assumes that the injectors are clean and functioning properly.

rick1025

I have the same problem with an 05 with Stabilitrac. It does not do it when the traction control is disabled.I have learned to put up with it.I have learned to disable it upon starting the car.