[sw904]

Replace the clutch fan. With only gm parts. Recently just changed mine and had same issue would just stall at red light and low idle sometimes and while making a slower turn. Only code was p0440. Would die no other codes ever

Diagnose first. One of the ways you can show it's probably not the fan clutch is by unplugging it BEFORE spending $$$.

 

[ak342058]

I’ve had my 2003 4.2 L6. Since 2006. I’m very positive with diagnosis. And only part I just replaced 2 days ago drove many miles since and hasn’t had any problems since. I’m sure this problem has plagued many people with out ever finding it.

 

[Ravalli Surfer]

I know it doesn’t make sense but the vvt. Variable valve exhaust circuit runs on same circuit. Some nazi posters here still don’t know and can’t seem to help or want millions of details

I understand that the right rear backup light can cause this problem too.

Where do you get off misdirecting the OP?

You're 4 posts IN and you're saying that others here are stupid? Isn't that a little lot presumptive and drawing to a wrong conclusion?

Just sit still and watch the show for a while and you will get more respect when/if you finally have something intelligent to say.

 

[chem_man]

@ak342058 -

I know it doesn’t make sense but the vvt. Variable valve exhaust circuit runs on same circuit. Some nazi posters here still don’t know and can’t seem to help or want millions of details

Exactly what in the "...Variable valve exhaust circuit..." is on the "...same circuit." - the VVT solenoid, the camshaft position sensor, the camshaft actuator?

Additionally, exactly what circuit are you referring to?

If you know something that we do not know, then in the spirit of sharing and educating those of use who use the forum, please share it with us.

 

[merlinof2]

Ummmm, trying to stay on topic here.
Just had a possibly similar problem. 2006 Envoy Denali XL 5.3L, would run fine until it got hot. Then just die suddenly, once while driving, twice after stopping. Trying to restart would only have the engine turn over fine, but never "fire".
Turned out to be the connector wire on the bottom of the fuse box from the Fuel Pump Relay to power?. Pic attached, see blue circle. that little bend "breaks" and separates when hot, effectively taking out the fuel pump relay...

 

[sw904]

Ummmm, trying to stay on topic here.
Just had a possibly similar problem. 2006 Envoy Denali XL 5.3L, would run fine until it got hot. Then just die suddenly, once while driving, twice after stopping. Trying to restart would only have the engine turn over fine, but never "fire".
Turned out to be the connector wire on the bottom of the fuse box from the Fuel Pump Relay to power?. Pic attached, see blue circle. that little bend "breaks" and separates when hot, effectively taking out the fuel pump relay...

Thanks for chiming in.
The 'simple' can be the hardest to diagnose, and after firing the parts cannon, still requires to be fixed.

 

[merlinof2]

Thanks for chiming in.
The 'simple' can be the hardest to diagnose, and after firing the parts cannon, still requires to be fixed.

Welcome. It was a discussion board similar to this that pointed me in that direction. The break was almost microscopic and really only tangible when I pulled the wire out. Purchased a fuse box for a 4.2L 6cyl as the fuse boxes for the 5.3 were non existent. Same Fuel Relay wire, so just inserted that and "poof", all was well, for a week when I had the other issue I detailed in another post.

 

[Ravalli Surfer]

I used some German Hard Solder (Sil-Fos) on that same problem -- solved it and it never came back.

Those wire "joints" are susceptible to vibrations that can kill them --- there isn't so much "pulling" or "tugging" on them which would be much more understandable.

In the past --- and I guess much into the future --- I have re-flowed solder joints on a lot of different boards and joints and even German Soldered a lot more --- the solder joints are iffy --- but they usually work for a lifetime more.

 

[ijackson26]

My trailblazer shuts off while driving down the street and I done fixed a oil thing but something else is wrong with it now and I don't know what it is

 

[Ravalli Surfer]

My trailblazer shuts off while driving down the street and I done fixed a oil thing but something else is wrong with it now and I don't know what it is

We won't have any idea either unless you create your own post with your statement in the form of a question.

 

[merlinof2]

OK, because I had the exact same issue on my 06 Envoy Denali XL with 5.3L engine, 2WD. I've got 220K on the truck and I love it... suddenly started, after driving for a while (got hot), engine would die. All electrics are still functional, radio, windows, etc. You could attempt to restart the truck, but it would only turn over, and never fire up.
Bottom of Engine Compartment Fuse Box has fine copper wires from fuses to connector. The one for the Fuel Pump Relay breaks with age, and when hot, separates, thus depriving engine of fuel. Let vehicle sit for a while and cool off, it restarts. Until it gets hot again and the saga runs again. Here is a link to a youtube fix for the wire, and a pic showing where mine broke, (the most common portion). This is apparently a common problem and I'm hoping this info helps:

How to diagnose and fix fuse box fuel pump relay issue

 

[tinmanwpk]

OK, because I had the exact same issue on my 06 Envoy Denali XL with 5.3L engine, 2WD. I've got 220K on the truck and I love it... suddenly started, after driving for a while (got hot), engine would die. All electrics are still functional, radio, windows, etc. You could attempt to restart the truck, but it would only turn over, and never fire up.
Bottom of Engine Compartment Fuse Box has fine copper wires from fuses to connector. The one for the Fuel Pump Relay breaks with age, and when hot, separates, thus depriving engine of fuel. Let vehicle sit for a while and cool off, it restarts. Until it gets hot again and the saga runs again. Here is a link to a youtube fix for the wire, and a pic showing where mine broke, (the most common portion). This is apparently a common problem and I'm hoping this info helps:

How to diagnose and fix fuse box fuel pump relay issue View attachment 62723

Did you read post #30?

 

[merlinof2]

Did you read post #30?

It wasn't a question and I wasn't looking for help. I was posting information I found and discovered in fixing my issue where it may be of help to someone else.

Did you read Post #25 ??

 

[tinmanwpk]

It wasn't a question and I wasn't looking for help. I was posting information I found and discovered in fixing my issue where it may be of help to someone else.

Did you read Post #25 ??

Thank you for pointing this out to me. My apologies to you as I made a mistake as to whom I should have addressed. Obviously it wasn't you, it should have been ijackson26.

 

[merlinof2]

Thank you for pointing this out to me. My apologies to you as I made a mistake as to whom I should have addressed. Obviously it wasn't you, it should have been ijackson26.

No Problem...

 

[Bwhite04]

I would like to hear more details about this right here. Like is there a commonality to when it happens.

Highway speeds or slow city traffic or both?

Always while moving or when you come to a stop?

What does the instrument cluster do right when it dies? Do some gauges still work while you are coasting to a stop if not already stopped? What warning lights come on?

When it dies does it sputter a little like it is trying to keep going or does it stop dead like the key was turned off?

How long does it need to "rest a little" before it will start again?

When it does restart will it startup like nothing happened or does it take some cranking and starts rough?

My 04 trailblazer is doing the same thing as Hers. my truck will crank fine but anytime I give it any kind of significant throttle it’ll die, by this I mean at 35 miles an hour at 20 mph it doesn’t matter the speed. If I baby it I can get a little faster after it dies I can wait like 20 seconds and it’ll crank right back up, no problems and it’ll run for hours while idling. I can give it throttle and redline it while it’s in park but I put it in gear and start driving and give us some throttle it’ll die and it’ll choke out it’ll stutter and then try to crank it up it’ll wait again

 

[metalmike187]

My 04 trailblazer is doing the same thing as Hers. my truck will crank fine but anytime I give it any kind of significant throttle it’ll die, by this I mean at 35 miles an hour at 20 mph it doesn’t matter the speed. If I baby it I can get a little faster after it dies I can wait like 20 seconds and it’ll crank right back up, no problems and it’ll run for hours while idling. I can give it throttle and redline it while it’s in park but I put it in gear and start driving and give us some throttle it’ll die and it’ll choke out it’ll stutter and then try to crank it up it’ll wait again

Any codes, pending or visible?

 

[Ravalli Surfer]

Isolate the TPS and look for major dropouts.

The TPS doesn't always pop codes --- seldom anyway.

 

[miss_rae]

Remove and clean the throttle body, including the throttle plate (affectionately called "the butterfly"). This is a common fail point in these model years. While you have it off, wipe out the intake manifold as best you can. Check the 710 cap for sludge as well as the nipple under the VORTEC resonator PCV hose. If so, @Ravalli Surfer has a great instructional video on how to use Berryman B12 to clean the PCV system, as well as how to test it.

The P0440 is a NIGHTMARE code to chase down, as it could be one (or both) purge solenoids, the tank itself, the fuel tank pressure sensor, the charcoal canister, the lines, the cap, the filler neck or the seal around the fuel pump. A couple of these issues also have another code with them, so more than likely if it's just the P0440, it could be the filler neck, cap, charcoal canister, one of the solenoids or a line. A smoke test will be able to determine what this is.

I didn't see you mention if you replaced your fuel filter. A restriction here won't set a code but could slow down fuel delivery. Also check your air filter and your fuel pressure regulator. There a small plastic and rubber line that connects from the VORTEC resonator to the fuel pressure regulator. Unplug it and smell it. If it smells of fuel, your regulator diaphragm is ripped and fuel is leaking. This could also cause driveability issues.

And if that vacuum line to the resonator doesn't just smell of fuel but leaks fuel and the resonator has gunk inside...the fuel pressure regulator is bad, right?

I have an 03 Envoy (not XL) and I don't believe it has the diaphragm, after an hour of googling. The connecting piece that attaches the vacuum line to the resonator is loose but I'm assuming that's not why it's leaking.

I should've started a new thread probably, but long time lurker, first time poster...and you seemed approachable based on your reply to Ms Sheila

 

[metalmike187]

And if that vacuum line to the resonator doesn't just smell of fuel but leaks fuel and the resonator has gunk inside...the fuel pressure regulator is bad, right?

I have an 03 Envoy (not XL) and I don't believe it has the diaphragm, after an hour of googling. The connecting piece that attaches the vacuum line to the resonator is loose but I'm assuming that's not why it's leaking.

I should've started a new thread probably, but long time lurker, first time poster...and you seemed approachable based on your reply to Ms Sheila

If you have fuel coming out of the regulator, the diaphragm is ripped. It's easy to replace and the part doesn't cost an arm and a leg.

Picture of what you're trying to describe could also be helpful.