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Fuel smell in cabin on a hot day

11K views 14 replies 5 participants last post by  RyanSubaru 
#1 ·
Car is 2005 obxt with 5eat and auto climate control.

Since yesterday I smell fuel inside the cabin, and I need some direction on where to start the troubleshooting.

Symptoms are:
1. fuel smell, mixed with some exhaust smell inside the cabin only, through the vents.
2. No smell at all inside the engine compartment or elsewhere around the car. I have not yet been under the car.
3. Only when the cabin fans are blowing with "fresh" mode. smell stops completely in recirculate mode or if fans are off.
4. same smell in AC or fan-only mode. Have not tried heater only, it's 90F degrees here.
5. No smell when I first turn the car on. Only when car has been running for a while. So only on hot engine.
6. No check lights. Car runs fine, idles fine, drives fine, everything works fine.
7. Most potent if I am stopped at a stop light (or just idling in parking lot).
8. Smell is very faint, almost undetectable if I am driving fast, say 50mph or more. I guess the wind is taking it away.

Some differential diagnosis...:
1. My last fillup was 2 weeks ago so it's not from that.
2. One possibility is the fact that I spilled almost an entire cup of subaru super coolant, and a tiny bit of ATF fluid, right onto the front exhaust pipes while I was replacing the water pump last week. I may not have cleaned it enough. BUT why would that smell like FUEL?
3. Not likely to be fuel filler neck since I only smell it on HOT engine and not on cold engine? Plus I live in salt-free Colorado.
4. Another possibility is there is a fuel line leak somewhere? It could just be any one of my many fuel lines that are now 9~10 years old.
5. I see no visible leaks of any kind from the top of the engine, but that's with the top cover on and I have yet to crawl under the car.
6. I read about the fuel line problems that Subaru cars have on cold days, but it is 90F outside so not likely?
7. It could be anything, last week I personally replaced timing belt, idlers, tensioner, radiator, water pump, radiator hoses, thermostat and both radiator caps. Maybe I screwed something up.
8. I don't see ANYTHING on the ground below the car. nothing. But then maybe things are being caught on the under shield.
9. I know what a torn CV boot does, and how that smells, and this does not smell like that.

I drove it for 20 minutes up and down the highway (65mph) hoping that it will burn off whatever crud I may have spilled when I was working on the car last week. Smell is the same.

Any direction for me? Thanks!
 
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#2 ·
#4 ·
#5 ·
"This also caused a a carbon monoxide leak into the cabin."
Yikes. I wouldn't even know how to find a leak in the exhaust. :28:

I will just go over all the rubber fuel lines and see if any of them are hard or brittle, and see if any of the clamps are loose. Worth checking on a car this age anyway. Hopefully that's it.

If that doesn't work I'll give the exhaust system a look.

Man with 120k lots of small problems are cropping up their heads. :(
 
#6 ·
I found this in the 2005 factory service manual.

Gasoline smell inside of compartment
Possible cause
1)Loose joints at air breather tube, air vent tube, and fuel filler pipe
Corrective Action
Retighten.

Possible cause
2) Defective packing air tightness on the fuel saucer
Corrective Action
Correct or replace the packing.

Possible cause
3) Inoperative fuel pump modulator or circuit
Corrective Action
Replace.
Trouble is, what "air breather tube" and "air vent tube" are they talking about? Can't be the one on the transmission, so where is this magical air breather tube in the fuel system?
 
#7 ·
Trouble is, what "air breather tube" and "air vent tube" are they talking about? Can't be the one on the transmission, so where is this magical air breather tube in the fuel system?
By federal law, the gas tank has an "EES" (Evaporative Emissions System)

Basically, the EES is a hose connected to the top of the gas-tank which routes gasoline-fumes into a charcoal-canister for storage when parked. When you drive the vehicle, the charcoal-canister is purged by sucking the stored fumes into the engine intake-manifold.

I connot speak for your Subie... but on my 2006 Baja, the charcoal-canister is located behind the right-rear wheel tucked up behind the fender.

Be aware that sense the EES is federally-mandated, there is also a complicated diagnostic-system built into the EES. One of the diagnostics uses an air-pump to slightly pressurize the air above the gasoline in the tank. Then, the system is sealed for several minutes and if the pressure leaks-out, it is considerd a FAIL and you will get a lite on the dashboard. (This is why a loose gascap will cause lite on the dash!!)
 
#8 ·
The only thing I found was a weeping hose on top of the power steering pump, which I clapped down. There is a small oil spot spot right behind the turbo, the one on top that is easy to reach. Curiously, this place has two copper gaskets on it where as I only see one in every diagram I have found. I know the turbo was replaced at some point... Could be a leak there I guess?

If the fuel lines are the issue I won't be able to fix it because many of them are not reachable without taking the manifold apart. Which I guess I could do but it would not be the first thing I tackle. I may use the bike wire method first.
 
#9 ·
I think I found the cause, my oil filler neck was cracked. Not leaking a lot but maybe it was allowing vapors? The inside of the filler neck smells exactly like what I was smelling inside the car.
 
#10 ·
Ah, good find. Also sounds like you need a new o-ring at the power steering pump L attachement. Easy to replace, and a good time to do a power steering fluid flush... Read up on it, done by hand rotating the power steering pulley.
 
#14 ·
BTW: I replaced the PowerSteering fluid on my 2006 Baha Turbo (Same engine as your Forester) a couple weeks ago. At 105,000 miles, the original fluid was BLACK.

I ended up changing the fluid TWICE.... the first time only ended up with brown fluid.
After a week or so to flush the system, I changed it again... and it remained red as Dexron is supposed to be.

I also used the "spin the power-steering pump by hand" method which TOTALLY replaces the fluid unlike the "turkey baster" method.
 
#15 ·
I have the exact same smell in my OBXT, but it's coming more from the outside and towards the back for me. It only does it when the engine is hot from going up my street when it's 90* out. And it's a really strong smell too. It's coming just before the rear wheels. Makes me think a bad fuel pump seal? Maybe cracked lines? This car was previously owned in the east coast so it wouldn't surprise me if it was rusted or dried out from salt. Thanks for any help.
 
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