SOLVED! TB starts then dies like fuel pump goes off

[04trailblazer1991]

Hello im stuck. My 04 tb died on the hiway yesterday and will not start up. It starts but then dies as if the fuel pump goes back off. I have changed the crank sensor. Checked for fuel at regulator.. all the usual suspects even checked all the pins at the fuel pump relay .. the only thing im left wondering is if it can be the ignition switch? Thanks please

 

[04trailblazer1991]

Im stuck! I thought between fuel pump and or crank sensor id fix it today but it seems like fuel pump stops or wont run when car starts. Once it dies the fuel pump kicks on and reprimes...

 

[Mooseman]

Hi and welcome.

Check fuel pressure. It could be a dying fuel pump that intermittently stops. And to check if it is a fueling problem, when it does die and won't restart, try using starting fluid to see if it will start. This would confirm a fueling issue.

Treat this as a crank no start condition and read through this thread.
Cranks but won't start

 

[Mooseman]

And now that you have replaced the crank sensor, you may need a CASE relearn if it throws a code for it.

Are you getting any codes?

 

[04trailblazer1991]

And now that you have replaced the crank sensor, you may need a CASE relearn if it throws a code for it.

Are you getting any codes?

No codes. It always starts. But dies once starts up. As if the fuel pump turns off n when dies u hear pump kick on and prime again .... ill be testing fuel pressure when can get a guage. But does this sound like a bad ignition switch?

 

[mrrsm]

This Thread may hold the answer to this problem... possibly being caused by a Faulty or Loose Ground at G-107 on the Driver's Side Lower Engine Block.

The Left Turn Signal, The Left Headlight AND the Fuel Pump Relay ALL share the SAME Ground... and if not properly grounding.... will cause the Fuel Pump Relay to kick OFF and Stall the Motor:

Source: "The Roadie"

NEED HELP - Engine dies with DRL on

I have a 2006 trailblazer I have several problems but the main one is every time i start the truck it dies unless i turn the daytime running lights off. with the lights off it runs fine as soon as you turn them on it dies. 2nd problem is i noticed that when i turn the key forward my cel does not...

gmtnation.com

Engine quits when left turn signal is on!!!

My 02 Envoy has developoed a bizzare situation. When I turn the left turn signal on, the engine quits. I can't tell if I am losing the fuel pump or spark, the tach still registers as the engine is turning over. I turn the signal off and it will either resume running (at highway speed, it just...

gmtnation.com

Also... If the HDM Headlight Relay goes 'sideways', it is NOT like a Typical Relay since it uses PWM control (Pulse Width Modulation) from the PCM to regulate DRL (Daytime Running Lights) and IT can also cause the the Engine to Stall Out. Avoid substituting ANY After-Market Relays here and strictly use the $40.00 ACDelco Part# 15016745

 

[04trailblazer1991]

Thanks i will totaly check that...
Ive now replaced the ignition switch and its still doing the same thing. Starts then shuts off within 2 -3 seconds...
My fuel pressure gauge is reading nothing idk whats wrong but i do have pressure. I can release it from the scrader myself.... im really stuck

 

[Mooseman]

Which schrader valve are you using? On your 04, should be under the truck beside the fuel filter, which wouldn't be a bad idea to replace if it hasn't been done in forever. The schrader valve under the hood next to the PCM is for evap testing.

 

[04trailblazer1991]

Which schrader valve are you using? On your 04, should be under the truck beside the fuel filter, which wouldn't be a bad idea to replace if it hasn't been done in forever. The schrader valve under the hood next to the PCM is for evap testing.

Yes im testing from under at the fuel filter. Brand new fuel pressure gauge kit. Screw it on. Pisses bit of fuel but reads nothing even when crank... but its prime sounds so healthy. And when disconnect line from filter n crank she sprays good....
So your saying replace my scrader before assume guage isnt working correctly?
Thanks so much for help. Currenly stumped with only grounds to go over tomorrow as possible ideas.

 

[04trailblazer1991]

This Thread may hold the answer to this problem... possibly being caused by a Faulty or Loose Ground at G-107 on the Driver's Side Lower Engine Block.

The Left Turn Signal, The Left Headlight AND the Fuel Pump Relay ALL share the SAME Ground... and if not properly grounding.... will cause the Fuel Pump Relay to kick OFF and Stall the Motor:

Source: "The Roadie"

View attachment 102531

NEED HELP - Engine dies with DRL on

I have a 2006 trailblazer I have several problems but the main one is every time i start the truck it dies unless i turn the daytime running lights off. with the lights off it runs fine as soon as you turn them on it dies. 2nd problem is i noticed that when i turn the key forward my cel does not...

gmtnation.com

Engine quits when left turn signal is on!!!

My 02 Envoy has developoed a bizzare situation. When I turn the left turn signal on, the engine quits. I can't tell if I am losing the fuel pump or spark, the tach still registers as the engine is turning over. I turn the signal off and it will either resume running (at highway speed, it just...

gmtnation.com

Also... If the HDM Headlight Relay goes 'sideways', it is NOT like a Typical Relay since it uses PWM control (Pulse Width Modulation) from the PCM to regulate DRL (Daytime Running Lights) and IT can also cause the the Engine to Stall Out. Avoid substituting ANY After-Market Relays here and strictly use the $40.00 ACDelco Part# 15016745
View attachment 102533

So i did swap out few relays to check that.... oops. Do you know which number your speaking of so i can make sure it has the correct relay ? I was unaware of this .

 

[04trailblazer1991]

 

[mrrsm]

Sure...

 

[04trailblazer1991]

Sure...

View attachment 102536

Ok i have not touched this one at all. So your saying replace that one n GM ac delco only. Im pretty sure its the same exact as the others but i maybe wrong. Appriciate your time so much thanks

 

[mrrsm]

I'm NOT advising that you Replace THAT particular Special Relay out of hand... Just that you be aware that IT can cause the SUV Engine to Stall due to the DRL (and Bad Ground at G-107) Issues.

Try to investigate its behavior by removing it temporarily ...and see if it is indeed "The Culprit". IF it proves out to be the "Keyser Söze" in this case, just be certain to stick with replacing it with the $40.00 + GM OEM (ACDelco) Relay ...IF... replacement becomes necessary.

THIS suggestion is just One More Thing to Check Off your list of ALL the Diagnostic Possibilities...

Adding to that List...

The Third Sentence in your opening gambit was, "I have changed the Crankshaft Sensor..." But... You have not mentioned the Mileage of your GMT360. In some cases for High Mileage Motors, a very small deviation between what the PCM is reading to compare the A/C Signals from the (CKP) Crankshaft Sensor (Reading the Crank Reluctor Wheel Notches) versus the Hall Effect Signals coming from the (CPS) Camshaft Position Sensor (Reading the Absolute Position of the Exhaust Camshaft) located in the front upper area adjacent the Timing Chain Cover on the Passenger Side of the the Engine. These Two Signals can deviate enough to make it unable for the PCM to Time and Fire the EFIs... and Most Importantly... Correctly Time the Ignition Spark:

Chevy Trailblazer P0017: Crank/Cam Position Correlation – Bank 1 Sensor “B” | Drivetrain Resource

P0017 in the Chevy Trailblazer is predominantly caused by a few different things. It is typically thrown when the Crankshaft Position Sensor and the Camshaft Position Sensor are out of alignment by a certain number of degrees, or if there is an issue with the wiring, or one of the sensors...

www.700r4transmissionhq.com

Check Out Posts #21- #23 in THIS Thread where I explain the DIFFERENCES between a Known Good CKP-vs-CPS Wave Form Alignment... when compared against a BAD Wave Form Alignment between these two Sensors as Viewed on an Oscilloscope:

"Timing... IS Everything..."

How To Use PICO #2204A & HANTEK #1008C Oscilloscopes

You don't need a Huge Bag of Coins in order to obtain and use an Oscilloscope for performing In-Depth Wave Form Analysis in Automotive Applications on everything from Problematic Electronic Fuel Injection to obtaining accurate Compression Tests to Diagnose Internal Engine Conditions. HANTEK...

gmtnation.com

In some cases, the Timing can get so Out of Whack as to prevent the Engine from running. In some instances where a P0017 and/or a P1345 Codes are displayed... the Timing Accuracy necessary will have been ruined by combination of Excessive Timing Chain Wear; including the Chain Stretch, a Fully Extended, Un-Retracted Timing Chain Tensioner AND Badly Grooved and Worn In Timing Chain Guides.

 

[04trailblazer1991]

Tomorrow without any other advice i will be
1.going over grounds n redoing some key ones.
2. lookn at relay 46
3. Checking if my brake pedal and shifter click when key is on as the USED to and still should

Today once 1 seen how much fuel pumped from pump i really thought was going tobe ignition switch which i hadnt ordered so i got n installed to no avail....
and my fuel pressure gauge read zero. Itl pump 1 quart in under 10 secs easy when lines off fuel filter. So i expected more than ZERO psi... uggg i need my truck back. This is some random bozo issue. Trucks prestine n well updated in external parts already... i use for my business. Canceling jobs each day i cant fix...

fuel pump and cam sensor n ignition cylinder arrive thursday.

 

[mrrsm]

Check the present Static B+ Voltage of your SUV Battery...and if you have one available and no excessive Fuel Fumes present around the Vehicle... Put the battery on a Trickle Charge overnight.

Be advised that prior to Changing the Fuel Pump... it IS possible to passively diagnose whether or not there is a problem with it...using a Current Fuse Loop, a Low Amperage Current Clamp and an inexpensive Oscilloscope as covered in Post #2 below:

How To Use PICO #2204A & HANTEK #1008C Oscilloscopes

You don't need a Huge Bag of Coins in order to obtain and use an Oscilloscope for performing In-Depth Wave Form Analysis in Automotive Applications on everything from Problematic Electronic Fuel Injection to obtaining accurate Compression Tests to Diagnose Internal Engine Conditions. HANTEK...

gmtnation.com

 

[04trailblazer1991]

Check the present Static B+ Voltage of your SUV Battery...and if you have one available and no excessive Fuel Fumes present around the Vehicle... Put the battery on a Trickle Charge overnight.

Ok i will because its currently LOW. It still will start it n then die. But almost barely... i was wondering if batt toooo low... but soon as its spinning the alter should put 14 v so i didnt bother.... idk if have trickle. But i should prob hook up jumpers to bring back up the front n rear battery i have back up.... thanks

 

[Mooseman]

Stupid question but I have to ask. Do you have enough fuel in it? We have seen this before where it was the fuel gauge not working properly and it was out of gas.

Otherwise, if you hear the pump and there is no pressure, check for fuel flow out of the line at the fuel rail. Could be a faulty fuel pressure regulator that's bleeding all the pressure.

 

[mrrsm]

...and Double Check that the (CKP) Crankshaft Sensor Harness Connector... is properly seated in ...very well.

 

[04trailblazer1991]

Will do. And yes ive added 3 gal before started digging in...
Main cuprits are
fpr And Fuel pump. I cant think of anything else. Shel start every time today but dies right when does.
Im going to jump some more power to the battery tomorrow..
Ive checkd n no security and safety switchs click... so just grounds tomorrow n crank sensor connector check. Then pop fuel line off at Fpr guess

 

[04trailblazer1991]

Post video tomorrow if can. Please check in

 

[Mathoran]

Might be a dumb question, but you say you used a fuel pressure gauge or was it a fuel pressure test kit? Reason I ask is a gauge may not come with the piece that pushes in the schrader valve so you would have to remove the valve to get a reading.

 

[04trailblazer1991]

This is the kit. It seems like the scrader on the line is to deep compared to other examples.... you think if i just remove scrader it would work? Good idea i will try!

 

[Mooseman]

While doing your testing, you can jumper the fuel pump relay between the 12V and Fuel Pump pins to keep it working constantly.

If you're still not getting fuel pressure or flow, this thread has lots of info for you to diagnose with, however it's a newer one without the fuel pressure regulator.

No fuel Pressure

I'm working on my father's 07' Trailblazer. The other day he started that on his way home that his trailblazer started to spit and sputter. He pulled of to the side of the road and shut the vehicle off for a few seconds. Turned it back on and it seemed to be ok except now his speedometer started...

gmtnation.com

One quick thing you could do to eliminate the FPR is to gently pinch off the return line near the PCM and recheck your fuel pressure. If it does have pressure then, I would replace it. You should also pull the vacuum line on it and see if there's fuel leaking out if it. You could also try to start it but this could damage the fuel injectors with excessively high pressure from the pump.

I've never seen a FPR fail by bleeding off all pressure. Most of their failures are leaking from the vent/vacuum line. From your symptoms and current results, I'm leaning towards a faulty fuel pump.

If it is the pump, you should get an ACDelco or Bosch for complete reliability. Whatever you do, as per that other thread, don't buy a Delphi.

 

[NJTB]

I've seen fuel pumps fail in a few different ways. The fact you have good flow with the key on, not started, but no pressure at the schrader valve (assuming the FP guage is good) may indicate there's flow but little or no pressure.
Watch the guage while cranking, if the pressure falls off below about 60psi, it's the fuel pump.
Make sure you get the ring that holds it on the tank, it's probably rusted to hell.

 

[04trailblazer1991]

Thank you again!... so ive gone over about 5 key ground and few others. Few werent great but no change...

Yesterday i had jumped that in my testing to verify all pins... so i could jump it and then try to start it n see what happens is what you recommended?? Sounds like great idea i will check..
Along side that i will be removing the scrader valve from the line n retesting FP... i dont think my gauge is activating the scrader...

 

[04trailblazer1991]

So she runs and stays running if spraying start fluid. So weak pump im thinkn. It arrives thursday.

 

[04trailblazer1991]

6psi. That explains working n starting but stumbling under load
Runs fine if sprayed start fluid.. ill drop tank tomorrow

 

[mrrsm]

"... And may the FORCE be with You.." :>)

 

[04trailblazer1991]

Fuel pump n crank sensor later and alls good. No case relearn n 20 miles later still no CEL.
The old fuel pump was already swaped it was chinese knock off... prob only 50k on it. BUY AC DELCO