"VOC" Smell in 1989 GMC Jimmy

[Skidoc]

Hi all,

I am trying to diagnose and solve an issue of an odor.

Got the car in CA, drove to NY last summer, redid the suspension, and most of the interior (except seats and rear side panels). The odor may have initially be covered up by the rotting wet carpet padding that smelled like wet dog, bc it was not noticeable before but maybe I damaged a fuel line putting in the suspension or something.

The car smells 24/7, not associated with driving. Never fully airs out. Doesn't seem to come from the HVAC. I can't smell it more in one part of the truck or other.

It is hard to place the smell, not quite like gasoline or other interior materials. I put an 'airthings' device in the car and it tests high on VOCs (volitile organic compounds). It has a pattern of when the VOCs are highest, daily rise and fall that starts around 9am and falls off around 4pm, as if related to heat/sun. On rainy days, the VOCs dont get pick up by the 'airthings' meter

I spent weeks airing out, nothing. I even got an ozone machine, kind of worked temporarily but not really.

Any experience with this? An experience mechanic around here told me that the gas tank sometimes rot behind the plate that protect the tank?

 

[Wes Harden]

Is the carbon canister still in the truck? Guessing this TBI fuel control system.

While it is possible the tank has some rot, I wouldn't normally expect that ofca California car. My 77 has original tank.
You shold be able to see most areas of tank with out removal.
Even the areas protected by skid plate.
Wouldn't surprise me if a rubber hose had split and allowing vapors to escape,check fill and 1/2" vent hose.

 

[Skidoc]

Thanks Wes!

I brought it to the mechanic to get a second look over.
We check all the obvious places and what you suggested Wes, the tank was clean, the carbon canister was in their but there was no filter, no obvious holes in the exhaust, no obvious fuel leak or oil leak

I am going to have do a tune up and change everything, see if it helps.

I might take the seats out and see if those have some smell, since i never change the covers or the cushions - just the carpets.

 

[imiceman44]

Thanks Wes!

I brought it to the mechanic to get a second look over.
We check all the obvious places and what you suggested Wes, the tank was clean, the carbon canister was in their but there was no filter, no obvious holes in the exhaust, no obvious fuel leak or oil leak

I am going to have do a tune up and change everything, see if it helps.

I might take the seats out and see if those have some smell, since i never change the covers or the cushions - just the carpets.

If it's a new carpet it will be releasing VOCs for a while

 

[Skidoc]

Thanks. I hope so and it is likely

Some of the home carpets I put in smell 6 mos later

 

[Skidoc]

1989 GMC Jimmy - stock, "California" truck
Hey guys, I spent some time "sniffing" around. The strongest smell (that is the same as inside) is coming from the EVAP canister in the front. I think there must be an issue there, because on hot days I smell the odor outside the car. I think it also explains that is smells "sweet" but not quite like gasoline.

Of note, I just did a full tune up and ever since the truck revs down when I stop at lights, could this be related?

My questions are:
1. Is this a reasonable source? the EVAP system?
2. If so, how best to trouble shoot? Check lines? Replace canister?

I was going to just start replacing parts but realized if there is something causing the system to fail and I miss it, it will just fail again.

 

[K85 Octane]

That canister should see vacuum and is controlled by your ECM (or whatever TBI gen cars called it)

Honestly though, I'm not running the canister. It's just vented. If you don't need it for emissions, pull it out and save on a shelf. Put an old sock over the line coming from the tank and drive it. Make sure the vacuum line is corked or that would be a vac leak. See what happens.

Edit: don't need to pull out, just pull the lines off.
If you REALLY wanted to get creative, run the vacuum line to where you can see the end. Put a gauge on and see if there's vacuum while driving. (Might not be all the time, just some times) Then you'll know sensors, computer, lines, etc AFTER the canister are working.

 

[K85 Octane]

Or roll down your windows/tube doors

 

[Skidoc]

Ha, I have been leaving it rolled down 24/7 - doesn't help fully, it just comes back. I wish that was the solution, that'd be easy!

OK, i just realized that where we put the steeringbox support brace from ORD forced us to bend up the metal EVAP tubing from the tank along the front of the frame, I wonder if it cracked or kinked.

 

[Skidoc]

Is the carbon canister still in the truck? Guessing this TBI fuel control system.

While it is possible the tank has some rot, I wouldn't normally expect that ofca California car. My 77 has original tank.
You shold be able to see most areas of tank with out removal.
Even the areas protected by skid plate.
Wouldn't surprise me if a rubber hose had split and allowing vapors to escape,check fill and 1/2" vent hose.

@Wes Harden
Wes, you went to exactly the right place on your first response... I was knucklehead and misunderstood, when I checked what I thought was the carbon canister, I checked wrong.

Do you think it is as easy as just changing the canister? I'll try to test it by unplugging like @K85 Octane suggested - but I would prefer to restore the system to normal function

 

[Wes Harden]

That canister looks pretty good, though can't see the important part. I am not sure changing it will solve the issue. Have all the rubber lines and fill hoses been checked for cracks