NEED HELP 2006 Chevrolet Trailblazer EXT 5.3 Losing power and stop

Dipper

Original poster
Member
Jun 7, 2019
6
Texas
The other day my trailblazer was going along fine and all of a sudden it started losing power and stopped. I try to crank it, but it wouldn't turn over. After about 20 minutes of waiting, It started up and ran fine all the way home which was about 20 miles away.

The next day got up and drove 20 miles shut it off, went in for a doctor appointment. Came out I started my vehicle, it ran for about five minutes lost power and stop again.

I took it to a mechanic and they put the computer on it, it came back reading that it was a problem with the "Camshaft Sensor." Replaced it, drove it today's later and everything repeats itself. All the codes were cleared. Do not know what else it could be. Suggestions???
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
When it refuses to start, does it crank (starter engages) but just doesn't start?
 

Dipper

Original poster
Member
Jun 7, 2019
6
Texas
Yes the starter is engaging, but it won’t turn over. It Makes all the noise that is about to start but it doesn’t start. But after waiting for about 20 minutes or so, it starts up, and off we go.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
When it refuses to start, can you hear the fuel pump when you turn the key to RUN? It could be a dying fuel pump.
 

Dipper

Original poster
Member
Jun 7, 2019
6
Texas
No I didn’t know that you can hear it. I will check it tomorrow. So does it make a whining noise or something?
 

christo829

Member
Dec 7, 2011
497
Fairfax, Virginia
When you turn the key to RUN, you should hear a high pitched whine from the gas tank for a couple of seconds. That's the pump priming up. If it's particularly noisy where you are, you might need to have someone else listen for it or turn the key while you listen.

Good Luck!

Chris
 
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Dipper

Original poster
Member
Jun 7, 2019
6
Texas
OK, so I once heard someone talk about doing a fuel pressure test, I guess that test would indicate it’s at full pressure?
 

mrrsm

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Supporting Donor
Member
Oct 22, 2015
7,642
Tampa Bay Area
Okay… To sort of tell “The Story of a Failing Fuel Pump” as the possible cause of this Shut-Down-Starts-Back-Up-Later Syndrome” … I’ll use Minimal Dialogue (ordinarily ...very rare in most of my responses) and use ‘discreet imagery’ as a better way to explain all of the things required for Testing and Diagnosis of the GM Truck/SUV Fuel Pump as being the possible source of this problem:

Symptoms:

The GM Trucks and SUVs Start just fine and Run for around 5-10 Minutes ...before suddenly shutting down. After waiting brief periods ...the Vehicles WILL Re-Start and Run… and the sequence of events may return to having these Unnerving Shut-Downs happening :

Diagnosis:

First... For The Average Mechanic in possession of a GOOD Digital Multi-Meter that can read at or above 20 Amps… THIS is simple and expensive way to Diagnose a Failing Fuel Pump:


(1) Set your DMM to read 20 Amps.

(2) Insert your DMM Probes with Proper Polarity into the vacant PCM-B Fuse slot in the Power Distribution Center… Like this:

PCMB20APMFUSEANDFPRELAY1.jpeg

PCMB20APMFUSEANDFPRELAY.jpeg

PCMB20APMFUSEJUMPERWIRE4.jpeg

USINGDMMPROBESTOCONNECTHRU20AMPFUSE.jpeg

(3) Start the Vehicle and observe that the DMM will be acting like the 20 Amp Fuse to Keep the Engine Running as long as the Probe Points are connected to the PCM-B Fuse Insert slots like this:
DMMSETAT20AMPSTESTINGFUELPUMPAMPS.jpeg


(4) The Fuel pump for GM Vehicles should only be Drawing around 5 Amps if it is Properly Functioning. However… if the Amp reading is ABOVE 5 Amps… You should begin to suspect that the Fuel Pump ‘innards’ are drawing WAY Too Much Current for any number of reasons… and it GRADUALLY HEATS UP AND FAILS AS A RESULT. After brief periods when geing inoprative... The Fuel Pump Internals COOL DOWN and the Punp can begin to Work Again. Look at THIS High Amperage DMM Reading on a GM Tahoe with the Same 5.3L Engine as the OP’s and observe how much more Current is being Drawn by the Pump:

DMMSETAT20AMPSTESTING20AMPFUSE1.jpeg

(5) This Diagnosis Strongly Suggests that the Fuel Pump must be Replaced… HOWEVER… If you lalso ook at the Very Poor Condition of the OVERLY CLOGGED AIR FILTER that came out of this same Vehicle… Air Starvation and a Very Filthy MAF-IAT Sensor can ALSO cause Sketchy Problems in combination with a Failing Fuel Pump to make the Engine Misfire and Stall very quickly as soon as the Fuel Pump begins to Struggle:

AVERYCLOGGEDUPAIRFILTER.jpeg

(7) After Putting in a New Air Filter and Fuel Pump… Clear any remaining Trouble Codes and Fire Up the Motor to see if things run Nominally.


And here... For the Privileged Few In possession of either a Snap-On Vantage Scanner or similar High End Scanner… are Additional Instructions on How to Do the Following:

(1) Shut off the Vehicle, Raise the Hood and Uncover the Power Distribution Center.

(2) Locate the 20 Amp “PCM-B” Fuse right next to the Fuel Pump Relay as shown here:

PCMB20APMFUSEJUMPERWIRE4.jpeg

(3) Pull the PCM-B Fuse like this:

PCMB20APMFUSEANDFPRELAY1.jpeg

(4) Insert a Single Closed Wire Jumperin between the Two Fuse Terminal Connectors in the PCM-B Fuse Position... like this:

PCMB20APMFUSEJUMPERWIRE2.jpeg

(5) Set your Snap-On Vantage Amp Clamp Tool to the 20 Amps Setting ...like THIS:

VANTAGEAMPROBE1.jpeg

(6) After plugging in your Amp Clamp to the Vantage Scanner… Clamp it around the Single Closed Wire Substitute plugged into the PCM-B Fuse port ...like this:

VANTAGEAMPROBE2.jpeg

(7) Navigate to the Vantage Diagnostic Ssettings to read the Electrical Wave Graph Form and after Starting the Engine... COMPARE the Known Good Wave Form (Nice, Regular, Round ‘Humps” Hi-Lighted in RED) to the performance of the Fuel Pump Live Wave Form (Hi-Lighted in Yellow)… Like This.

gm53lfuelpumpwaveform1.jpeg

(8) If you notice that the Wave Form gradually fades flatter and flatter, it could mean that the Amp Clamp needs to be properly re-positioned around the Single Closed Loop Probe Wire… or that the Fuel Pump is FADING ...like this:

gm53lfuelpumpwaveform2.jpeggm53lfuelpumpwaveform3.jpeg

(9) If you observe a “Clipped”Wave Form on the Live Feed from the Fuel Pump on the Oscilloscope Graph Screen… this also indicates a Failing Fuel Pump… Like this:

CLIPPEDWAVEFORMOFUELPUMP1.jpeg

(10) The OBD2 Scanner showing P0300 Code indicates Random Misfires, possibly caused by a failing Fuel Pump that LEANS out the EFI Fuel Spray enough to cause the Engine to Stagger, Stumble and even experience Shutting Down of the Motor ...from FUEL STARVATION.

ELITEOBD2SCANNERDATA1.jpeg
ELITEOBD2SCANNERDATA3.jpeg
ELITEOBD2SCANNERDATA4.jpeg



Tussen Takke... (A Thousand Thanks to the VOP Below...)

Props to the VOP (Video Original Poster) for making this very enlightening and inspirational Video these Screen Shots came from:

 
Last edited:
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