P0455 and slight gasoline smell in the cabin when hvac running on cool setting

[6716]

I put a new gas cap on and that did not fix it.

For whatever reason, when I was driving the truck this last winter, the code was set but I didn't have any gas smell. Now in the summer I do, but only when the blower motor is running ... and it seems like only when the hvac sliders are down on cold. I had this situation last summer as well, and didn't have it in winter.

Purge solenoid? I thought I read that would throw a p0442. Hoses? I don't find any videos for replacing hoses. Evap canister seems easy but I don't know that is the problem.

It's running fine, anyway.

Thoughts?

 

[Chemman]

Look at the area in front of the starter, that is where the EVAP purge solenoid is mounted along with a hose. P0455 means you have a large leak so you should be able to hear/feel something.

P0442 means a little leak.

 

[Mooseman]

Did you happen to hook up a fuel pressure gauge to the test port on the fuel rail? Check around there. I had the exact same issue right after checking my fuel pressure for a misfire issue and the stress on the port due to its awkward position cracked the fuel rail. Had to replace the whole thing. Also check the connection to the fuel rail and all the metal lines to the tank. I have one that rusted out in the Saab right at the tank plastic line connector. I smelled it before I saw it.

 

[6716]

Did you happen to hook up a fuel pressure gauge to the test port on the fuel rail?

I did not, nor have I worked on the fuel system beyond replacing the pump.
The service manuals posted here for 2005s don't seem to contain any information on the fuel system, and I don't find much on the internet for diagrams and such. Rock Auto doesn't have the rail itself (though there are lots of other parts). Other than where I would guess stuff should be I think I don't really know what I am looking at.

Oh, well. I'll pop the hood and take a look.

Any thoughts as to why I would only smell it with the blower on cold when it is warm out? It doesn't really matter beyond curiosity I suppose.

Thx.

 

[Mooseman]

You don't have to have the engine running. Just prime the system, turn off the key and start looking and sniffing.

 

[6716]

You don't have to have the engine running. Just prime the system, turn off the key and start looking and sniffing.

What do you mean prime the system? Like run the engine for a minute?

I just now saw your note. I pulled the pcm off of the intake manifold to get a better look at the lines. I haven't ever gotten into the intake manifold. I took off the throttle body as well, thinking that would let me see a little better into the rails. The lines are rusty in some spots but not so much in others. I didn't see anything obviously like a hole.

I'll put the throttle body back on, but just to make sure ... can I run the engine with the pcm off the intake manifold? I would think so, but thought I would double check.

 

[Mooseman]

What I mean with prime the system is to turn the key to RUN and the pump runs for a few seconds and stops. System should stay pressurized if there's no leak. And with the engine not running, you won't have the fan blowing air all over the place and making it harder to sniff for gas smell.

The PCM should be fine off the manifold but with my method, you don't need it running.

Edit: If you have or can get one, hook up a pressure gauge to see if it pressure holds. If you have a leak, it will be quickly evident.

 

[Blckshdw]

What do you mean prime the system?

Turn the key to the run position, you should be able to hear the fuel pump kick on, and put some pressure into the system.

Edit: Scooped

 

[6716]

Edit: If you have or can get one, hook up a pressure gauge to see if it pressure holds. If you have a leak, it will be quickly evident.

I can get a pressure gauge. I saw the one valve with a black cap near the rail, there is also one with a green cap underneath-ish the pcm.

What would proper pressure be? It runs so there must be some, right?

 

[mrrsm]

At around 2:00 into this Video from @MAY03LT... he quotes a Fuel Pressure reading of 54 PSI. However, it seems that his engine was running at a fairly High Idle during this Test. So without PCM encouragement via PWM to pump faster, with your engine NOT running and using the Key-Turn Fuel Pump Priming Method mentioned above the Fuel Pressure will be substantially lower:

Still... THAT Fuel Pressure SHOULD remain present in the system long enough for you to 'sniff around' and use a Fuel Safe Flash-Light to seek out any leaks; no matter how small. Not finding anything leaking depends upon NOT having any of the following remarkable issues present:

(1) The EFIs must NOT be leaking Fuel past their PWM controlled Pintle (Pintel?) valves into the Cylinders just past the Intake Ports in the Engine Head.

(2) The Fuel Pressure Regulator on the Early Model TBS & Envoys must NOT be Leaking Fuel:

(3) The Metal Fuel Lines must NOT have Rusted through on or around the Fuel Pump on top of the Plastic-Nylon Gas Tank. An incorrectly aligned Fuel Pump to Tank Seal may also be a point where leaks can occur around that hidden space.

(4) The Vapor Lines leading to and from the Charcoal Vapor Canister or the unit itself must NOT have clogged up inside.

If you cannot hear the Fuel Pump running in the short action of turning the Ignition Key just a bit... either one or all of these issues deserves investigation:

(1) The Fuses involved in the Circuit may have burned out.

(2) The Fuel Pump Relay may be INOP or may NOT be installed at all or the PINS are not making solid contact inside the PDC plug in points.

(3) The Fuel Circuit Wiring between the Power Distribution Center in between is leading to and from the PCM and the Fuel Pump is either Damaged, Disconnected or Shorted to Ground.

(4) The Ignition Switch must NOT be FUBARed or have the Nylon Teeth inside misaligned within the IGN Key Metal Lock-Work.

Fuel Safe - Explosion Proof Flashlight @ $22.00 on Amazon:

https://www.amazon.com/dp/B007RKKEQQ/?tag=gmtnation-20

 

[Mike534x]

We had a similar thing happen with our first Envoy (first 02 model year), it happened during the winter one year. We were driving and began smelling the faint odor of "gas" and then over the course of a day it got stronger. Upon looking under the truck, the fuel lines leading to the gas tank had rusted out. We had a recall notice from GM, so it costed nothing to have them replaced. Didn't set any codes either, which was odd.

You could check out the thread I had 3 years ago, dealing with a P0455 . Mine turned out to be a combination of the EVAP canister (near the spare tire) developing cracks, and the purge valve. It could be worth checking those two out? I'd check the filler neck/line leading to the canister too, maybe there's a small leak thats allowing fuel vapor to escape and giving that smell.

 

[6716]

You could check out the thread I had 3 years ago, dealing with a P0455 . Mine turned out to be a combination of the EVAP canister (near the spare tire) developing cracks, and the purge valve. It could be worth checking those two out? I'd check the filler neck/line leading to the canister too, maybe there's a small leak thats allowing fuel vapor to escape and giving that smell.

I definitely have read about the evap and purge valve, I am no stranger to shotgunning parts but I was hoping to avoid it in this case.

However, following the priming instructions, I could not smell gas in the engine area. I grabbed on the lines everywhere I could see them and I didn't come across any leaks. I looked under the truck and there were no (fresh) drips or any gas smell.\

So maybe I start shotgunning parts. Good news is the truck runs. And the evap looks like an easy job.

Emotionally I wanted the "it only produces the gas smell when the hvac is running and on cold" to be some super clue, but I guess it isn't.

 

[Mooseman]

It sounds like it's sucking the smell from the under the hood via the cowl vent. Have you tried putting the HVAC to recirc to see if it lessens the smell? It won't eliminate it since it always brings in some fresh air from the cowl.

I have to ask but are you sure it's a gas smell? Mine has a particular odour when I first start the A/C but it's more like a musty smell. I've been meaning to clean out the evaporator with a spray for that but haven't gotten to it yet because I also wanted to add a cabin air filter.

 

[rolo95]

Ok so im going to chime in , this did not happen to me but i was reading about it
one cause and i don't mean is your case ,is the fuel pressure regulator
when it start to fail, it leaks gasoline fumes that sneak into the cabin of the truck
i read that some people fixed that foul gasoline smell replacing that fuel pressure regulator

Again, maybe not your case but maybe it is

2004 CHEVROLET TRAILBLAZER 4.2L L6 Fuel Injection Pressure Regulator | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.

www.rockauto.com

prices from 42 for the cheappie one to 97 for the acdelco one

here is a video on how to replace it

 

[Mooseman]

His is a 2005 so no pressure regulator.

 

[rolo95]

Darn, my bad i tought all of the 4.2 I6 had it

 

[6716]

I have to ask but are you sure it's a gas smell?

Now we're troubleshooting! Question the assumptions!

I guess I am not sure it is a gas smell. It is indeed a smell that smells like gas, but maybe it isn't actually gas. How do I find the evaporator?

 

[Mooseman]

It's inside the HVAC plenum. You could take the fan out and look with a mirror or camera. Maybe take your phone with the light on and make a video to look at after.

 

[budwich]

now you are questioning yourself.... Is it gas fumes or exhaust fumes? Find a personal with a "nose" as perhaps you have gone "nose blind" to confirm...

My guess would be an exhaust manifold issue (ie. cracked or otherwise) causing fumes to be sucked in thru the cabin air intake.

 

[6716]

My guess would be an exhaust manifold issue (ie. cracked or otherwise) causing fumes to be sucked in thru the cabin air intake.

I feel like I would have a code for that.
Here is what I am thinking now: I have a large leak, yes, as evidenced by the P0455, somewhere, in some fuel systemcomponent. But my assumption that this fuel leak is connected to the odor that seems like fuel and is only noticeable when the A/C is on ... that may well be incorrect.
If I can correcting the P0455 by shotgunning parts and I still get the odor, then they are not connected. If I can correct the P0455 and it does, all the better.
So I think I will go after the code and see where that gets me.

 

[budwich]

"follow you nose"...
There isn't likely going to be any code for a "cracked exhaust manifold"... there is no system monitoring that sort of thing. IF it is really bad, then you may get some "lean codes" but only if it passes a limit which is quite high. I know from experience with the manifold that there are issues and they do tend to show up in your nose because of where the 4.2 exhaust sits and where the "in cabin climate stuff" is located.
For sure, address the p0455 although to me, that isn't an "important run code"... more of an "friendly environmental feel good" (my opinion).

 

[Mooseman]

Started writing this post last night and forgot to post it. @budwich beat me to some of these.

I feel like I would have a code for that.

Not necessarily. Lots have had cracked manifolds with no codes. Just noise.

So I think I will go after the code and see where that gets me.

Good idea. May need a smoke machine to find the leak though. Things to check are the fuel filler and the tank's filler neck. There's also a couple of valves on the tank for the evap and there's the fuel pump module seal and the module's top itself that could have rusted through.