2005 Trailblazer Starting Issues.

[Mothman]

This is my first post.

My brother has a 2005 Chevy Trailblazer LS with the 4.2 L6 engine. Over the past several months, he has told me of times when the car would not start. He said he would try every couple of minutes until it did start. It never took more than 3 or 4 tries. I cannot remember if the car would crank or not. I know at the time I was thinking it was the starter going bad. Just this past Thursday, 2/15/2024, I finally replaced the starter after he was stranded for nearly 30 minutes before the car would start.

The trailblazer started, allowing me to pull it into my garage. When I finished installing the new starter, the car would not start. I even put in the old starter to see if I had ordered a faulty starter, but all the car did was crank over. Occasionally, it would sound as if it was starting but putter out when I let go of the key. It seemed to me that it was not getting enough gas. However, I tried starter fluid a couple times to no avail. I know it's not the fuel pump relay because I swapped it with the horn relay which are identical. I tried jumping it but got nowhere with that. I even bought a new battery. This was all Thursday.

I left the battery completely disconnected overnight and, in the morning, I connected the battery and tried to start the trailblazer. It started up on the first, albeit it ran a little rough at first but settled out. I did not move it. I kept it in park. I let it run for a few minutes before shutting it off and trying to start it again. Nothing. It refused to start back up and would only crank. It sounded like it wanted to turn over but just would not. I tried starter fluid again but got nothing.

I left the battery disconnected again overnight and Saturday morning I tried starting it again and it started. The same thing happened where it ran a little rough but settled out. I let it go a couple minutes before shutting it off and trying to start it and it refused to turn over. I tried leaving the battery disconnected for a period of half an hour and then for an hour and it would only crank after each time period.

I bought a spark plug spark tester and a gauge to test the fuel pressure but just have not been able to test either yet. Any suggestions as to what it could be would be greatly appreciated.

 

[mrrsm]

Welcome to GMT Nation...

Given your solid approach and understanding of the Basic Principles of needing FAS (Fuel, Air (Compression) , Spark) without repeating an elaborate discussion of all of those steps... You might try Dialing In on things that are primarily Electrical from now on:

(1) Examine (R&R) ALL of your Driver's Side Lower Engine Block Ground Connections.
(2) Open the Fuse Box ***, Pull the Plastic Cover & TIGHTEN Down the 4 Galvanized Post Bolts.
(3) Use a Bright Flashlight & Examine the Under-Hood Harnesses for signs of Rodent Damage.
(4) Stress Test the Battery UNDER A LOAD (DC Load Tester) looking for a Bad Cell.
(5) The Ignition Switch can often emerge as the Prime Culprit. (Replace with ACDelco).
(6) Look for Signs of Green Corrosion on the Red and Black Battery Harnesses.
(7) Gently move Harnesses around once the Engine is RUNNING to see if the Motor DIES.
(8)...and So Forth as other ideas involving Electrical Cut- Off Sources occur to you...
(9) Be Fastidious, Be Suspicious... and Be Very Thorough as you perform Each Test.
(10) STOP long enough to Try and Start the Vehicle after each Test or Adjustment.

PS... If you have a Cracked Solid Copper Trace in the middle of the Fuse Box Sandwich... they can cause a temporary separation once heated up and then re-connect after the Engine and Bay locations Cool Down and (Wash, Rinse, Repeat) this Failure. There are specific, contemporary Threads covering THIS Topic here at GMTN, too.

***

 

[Mothman]

Update

Thank you for your response.

Last night, I tightened up the galvanized post bolts in the engine compartment fuse box. I did this before reconnecting the battery. It started up as it usually would after sitting disconnected for 8+ hours. However, it started up a few more times after the first start up where as before it refused to start up more than once. I left the battery connected overnight.

This morning, the car started. It had some moments of hesitation, but it started. The first start up sounded like it was being choked of something. It struggled to stay on until I pressed the gas pedal in. It settled out after that.

I connected my fuel pressure tester and I was getting 57 psi with key on, engine off. It never lost any pressure in this position or even when I removed the key. When the car was on, it was getting 60 psi and would stay there for the duration that it was running.

Each time it started, there was a second or two of hesitation before it settled out to normal. It seems to be consistently doing this now. I moved around the battery cables when it was running but nothing changed and it continued to run. I haven't checked anything else out yet that you suggested. I will have to look into the other threads about the solid copper traces inside the fuse box.

 

[mrrsm]

Very Encouraging News. The Starting - Rough Idle issues at or below 600-650 RPM is symptomatic of having a Dirty Throttle Body that deserves a "Bench-Top" Cleaning after following the "Throttle Body R&R" Youtube Videos" and the many available FAQ Threads to help deal with this issue.

Avoid using Brake-KLEEN and choose instead to employ stuff like Berryman B-12 Carburetor Spray to directly dissolve away all of the Dirt and Gas-Gum Build Up as a Solid Ridge that often catches the edges of the Butter-Fly Plate in front of and behind, just inside of the Air Inlet Venturi Chamber. "The Car Doctor" has an excellent Youtube Video on this issue.

Changing an often Tired and Neglected Air Filter and also using CRC MAF Spray to thoroughly spray out the MAF Internals is also worth doing. Again... avoid using any other Spray Solvents on the MAF's delicate internal Resistors for this purpose. The Engine will "Breathe and Behave" much better after performing these steps.

You don't mention the use of any Code Reader or inexpensive Blue Tooth to DLC Scan Tool to look for codes relating to issues either with the CPAS (Camshaft Position Actuator Solenoid) or with the CPS (Camshaft (Absolute) Position Sensor) ... but if such Codes emerge... there are Specific Threads dealing with "Poor Idle Issues" caused by either one or both of those items getting internally clogged and dirty or failing outright as well.

Our Resident SME (Subject Matter Expert) for all things OBD2 Scan Tool related is @TJBaker57 and his extensive Threads on this Topic and on the Torque App are always worth reading from start to finish and keeping up with his regular updates over time.

 

[Mothman]

I did have some codes that I forgot to mention in my earlier posts.

I removed the throttle body and cleaned it the best I could. Got most of the buildup removed using CRC throttle body cleaner and the butterfly plate didn't seem to be getting caught on anything. After some research, I discovered that my brother's trailblazer does not have a MAF. So I just put everything back together. It didn't seem to affect anything that much compared to before the cleaning.

Before the cleaning, I was only getting one engine code and that was/is P0526, Fan Speed Sensor Circuit. After the cleaning and after a few minutes of idling, where it dropped down to between 600-650 RPM, I got the code P0410, Secondary Air Injection System. Before I cleaned the throttle body, the idle was stay at or above 800 but now it stays in the 600-650 range.

There are no noticeable drivability issues.

 

[TJBaker57]

Before the cleaning, I was only getting one engine code and that was/is P0526, Fan Speed Sensor Circuit

This "could" mean there may be a problem with the wiring for the 5 volt reference circuit that supplies power to the cooling fan speed sensor.

That same 5 volt reference power supply goes to the accelerator pedal, the throttle body, and a handful of other sensors.

Since many sensors share the same power supply if any one of those circuits have a problem, then all of them may report a problem.

So you may get a throttle body sensor code when the actual trouble is the cooling fan sensor wiring or the accelerator pedal sensor wiring or the MAP sensor wiring. Or the reverse.

The P0526 only comes on when the trouble is seen in TWO CONSECUTIVE ignition cycles. This suggests you likely have a 5 volt reference power supply wiring issue somewhere.

It could be causing a host of symptoms.

 

[Mooseman]

The P0410 is caused either by a blocked passage, a defective valve or air pump (so pretty much anything and everything in that system). It can be eliminated by deleting this system.

Removing Secondary Air Injection System

My '06 needs a SAI pump, and while the cost of the pump isn't cheap, its also not too bad, looks like I can get one around $100. My bigger concern is these trucks tendency to devour SAI systems. I've had the valve replaced twice and now the pump is dead. Meanwhile, the SAI system isn't even...

gmtnation.com

The part may no longer be available from GM. You could get one from an 02-03 in a yard, fabricate one or slip a piece of sheet metal between the valve and the head.

For the P0526, if you decide to get the PCM reprogrammed for the SAIS delete, you can also delete the codes for the fan clutch and get a thermal one for an 08-09. Much more reliable and less costly.

 

[Realism]

The P0410 is caused either by a blocked passage, a defective valve or air pump (so pretty much anything and everything in that system). It can be eliminated by deleting this system.

Removing Secondary Air Injection System

My '06 needs a SAI pump, and while the cost of the pump isn't cheap, its also not too bad, looks like I can get one around $100. My bigger concern is these trucks tendency to devour SAI systems. I've had the valve replaced twice and now the pump is dead. Meanwhile, the SAI system isn't even...

gmtnation.com

The part may no longer be available from GM. You could get one from an 02-03 in a yard, fabricate one or slip a piece of sheet metal between the valve and the head.

For the P0526, if you decide to get the PCM reprogrammed for the SAIS delete, you can also delete the codes for the fan clutch and get a thermal one for an 08-09. Much more reliable and less costly.

I second this.
ALso you could try doing this. Disconnect your Fan clutch electrical connection. You will code for it being absent but the early years of the voy/tb used an Electroviscuous clutch and they suck, cause problems when they dying out, could help isolate as well. There was a guy somehwere on here or the old place, that would flash your ECM for you after you replaced a clutch for a thermal one. so YOu didnt get a code all day every day.

also it may be redundant, but can you probe your fuel pump? cuz my thought after reading a bit was you might have a pump that is on that cusp of going out. Can you hear it kick on when you move your key to the pre stage? every time?