unburned fuel odour

Hey all,

98 civic lx (canadian) 220000kms, 5 speed. I let
the car sit for a 4-5 days, then took it for a
boot on the highway yesterday. Today when I got
in and started driving, I noticed a definite
unburned gas smell. Not so severe that it smells
like its pouring out somewhere, but bad enough to
bug me.

Any ideas? The car has 3 month old wires, 1.5 year old
plugs, new dist cap and rotor in november. Mileage
has been OK, not stellar, I get 460kms on 35 litres
of gas, so about 12-13 KM/L or 28-32 Miles/US gall.
Located in Canada. Have not run any injector
cleaner for a while.

I did a visual inspection of the fuel system. No
drips visible. Injectors looked OK. I was
reminded that I am due for a fuel filter change,
I have one sitting in my trunk I haven't gotten
around to changing it as yet.

No hard starting, running fantastic, good acceleration
etc etc... Just the odor.

Any ideas?

Terry

 

x-posted to rec.autos.makers.honda, as this thread should have been in the
first place

When you say "unburned gas", do you mean an actual raw gas smell, or an
eye-searing, hydrocarbon stink from the exhaust?

Did you fill up recently? "Topping up" a bit too aggressively will cause
raw gas vapors to exit the EVAP canister vent, although in your case that
/should/ light up the MIL.

Any corrosion on the low-pressure fuel return line alongside the gas tank?
Any drips on the driveway next to the left rear wheel?

 

x-posted to rec.autos.makers.honda, as this thread should have been in the
first place

When you say "unburned gas", do you mean an actual raw gas smell, or an
eye-searing, hydrocarbon stink from the exhaust?

Did you fill up recently? "Topping up" a bit too aggressively will cause
raw gas vapors to exit the EVAP canister vent, although in your case that
/should/ light up the MIL.

Any corrosion on the low-pressure fuel return line alongside the gas tank?
Any drips on the driveway next to the left rear wheel?

 

Hey all,

The smell is coming from the engine bay. Its
hard for me to tell if it is raw fuel or just
unburned mixture. I would say closer to raw
fuel, it was given me a headache. Its more than
just a sulfury smell from the exhaust. Speaking
of which, if it was coming from the exhaust, that
would indicate an exhaust leak, right? Well
I don't think i have one, and my exhaust manifold
is pretty new, replaced on warranty...

I was actually very close to being empty tank today,
haven't filled for about 2 weeks.

PS regarding the x-thread, sorry... not sure
where to post where everyone will see it. I
can't seem to get used to outlook express to
view these damn things, so I am using
Talkaboutautos.com, and there are 2 separate
forums for hondas. What should I be using?

Thanks Tegger
Terry

 

so no ideas here tegger?

any other info helpful?

t

 

Assuming it's actual raw gasoline, it can only come from the delivery side.
The fuel is pumped up the high pressure line to the fuel filter to the fuel
rail and into the injectors. Excess fuel passes through the fuel pressure
regulator and goes back to the tank through the low-pressure line.

There are quite a few connections between the tank high-pressure side and
tank low-pressure side, all of which can leak. The injectors are prevented
from leaking only by O-rings at either end. They are just a press-fit in
the fuel rail and the intake manifold.

All I can think of right now is to make sure all hoses and lines are
correctly connected, not corroded or split, and the fuel injectors aren't
leaking at any of their top O-rings.

Start your observations at the fuel rail, and follow the lines back.

Sorry I can't offer more, but I don't know if there's a common failure mode
on this car that would result in a fuel smell in the engine compartment.

I know your exhaust manifold was replaced, but has anybody ever done any
work on the intake side?

 

By the way, has this car ever been in a collision or had the engine
removed? Either occurrence can result in pinched or otherwise damaged hoses
and lines.

 

I will check my injectors. They have never
really been serviced, and I am interested in
seeing what kind of shape they are in anyways.

The car has been in a couple collisions, but
nothing serious. No the engine has never been
removed.

Thanks
t

 

Check the evap system as well, and make sure all the hoses are still
connected and are not leaking.

 

Hey Tegger,

Figured this one out! Seems that one of my valve
cover bolts stripped its thread, and was not
seated properly to seal the valve cover, allowing
unburned combustion gases to escape, and ending
up venting into the passenger compartment.

Now I gotta figure out a way to fix the damn
thread... Probably a helicoil, but I can't find
a place that will sell me just 1 M6x1 helicoil,
they want me to buy the whole kit for $29.

Any ideas?

t