Gas smell - I need YOUR help!

[AutoXSHO]

Hey for once you guys get to respond to ME in a sarcastic manner, instead of the other way around.

Seriously, I need some help. I get a very bad gas fumes smell from the passenger's rear wheelwell (near the filter) when the car is driven on hot days. Here's what I've checked:

Ran fuel pump for a half hour to check rails, injectors, lines, filter, etc for leaks. None. No gas smell.

Checked vapor lines from vapor canister to vapor valve on top of gas tank. No leaks as per my vacuum pump tester. Checked vapor canister. It is not saturated (i.e. never smells like gas). Checked vapor canister purge valve (even tried bypassing it for a few weeks, no change) and it works fine. Replaced vapor vent valve and seal on top of gas tank. No change.

I see no dripping fuel. There are no liquid leaks - it has to be a vapor leak. But where? Ford dealer is stumped as well.

John V

<small>[ June 24, 2002, 10:05 AM: Message edited by: AutoXSHO ]</small>

 

[fredhurderjr]

Did you check for a cracked fill cap? How's that for sarcastic? wink

Also, is it possible you may have a crack in the top of the fuel tank, or at the fuel pump seal ring?

 

[AutoXSHO]

Haha.

Sorry, forgot to mention it has a new gas cap. I suppose it's possible the fuel pump seal is bad. I suppose I COULD drop the tank again... <sigh>

John V

 

[twr]

I copied this of of SHOtech - it was a response to what the extra hose that stops at the back of the car behind the rear passenger tire - I believe this might be the reason for the fuel smell back there.

The extra hose may be the fuel vapor recovery "fix" TSB from some years
back. I don't recall the TSB number, but it was a bandaid for a problem
which I believe Ford did not correctly identify.

Many early Tauri had a problem with fuel smell in the passenger
compartment during hot weather with the A/C on. The TSB fix was to
install a 15 foot long hunk of hose from the vapor vent on the Fuel
Vapor Recovery Canister (FVRC) and route the hose back to the rear of
the car, where the fumes would be less noticeable.

I've worked on several Tauri with this fix and have usually found that
the vapor vent solenoid valve between the FVRC and the throttle body
was
not opening, resulting in a saturated FVRC. In some cases, the vapor
vent valve itself was bad (open solenoid coil), in others, the EEC
driver channel for the valve was bad. Seeing as how I helped design
some
of the EEC-IV and V chipset, I went into the schematics and found that
Ford had selected a driver channel which had inadequate protection from
the back EMF generated by the solenoid coil. This back EMF eventually
destroys the driver transistor and renders the vapor vent solenoid
valve
inoperative. The same driver chip was used for the cruise control
vacuum
and vent solenoids, and somebody was smart enough to install catch
diodes in a little wiring harness between the cruise servo and the
engine compartment wiring harness, but the diode was apparently
forgotten on the vapor vent valve.

Check the operation of the vapor vent solenoid. Its hanging in the line
between the FVRC and the port on the forward side of the throttle body.
If its not working, I'd sugggest bypassing it with a short section of
1/4" O.D. copper tubing. Don't remove the red plastic orifice between
the valve and the TB, or there will be too much purge on the canister.

If the FVRC is saturated, the car may idle poorly, or not at all, until
the canister gets cleared out.

Terry

 

[AutoXSHO]

Terry,

Fortunately I'm on SHOtech, but as I mentioned this isn't a charcoal canister problem; or I don't believe it to be one. The charcoal canister would vent fumes if it was saturated, but that doesn't happen.

I'm guessing it's either a leaky fuel tank or a leaking fuel pump gasket.

John V

<small>[ June 24, 2002, 02:17 PM: Message edited by: AutoXSHO ]</small>

 

[twr]

John,
I quess I should have read the name in your sig, instead of just seeing the AutoXSHO. In the words of a wise man - D'OH!!

Terry

 

[SHOMA]

I know you checked it already, but if you can find a spare purge silinoid, the piece that the rubber hose off of the TB connects to, it might fix it... My 95 had the EXACT problem, and it was coming out of the "dead line" as I refer to it, and it just vents... UNDer extreme pressure, if the tank builds up pressure, it will vent from the hole, see if you have any coming out after shutoff.... Sounds dumb, but try driving for a day ro wo with the gas cap loose, if that fixes it, than 99% likely to be that purvge valve siliniod... Stupid question, but is the plug getting a signal? GOOD LUCK, let me know what happens! With my 95, I put the purge silinoid off of a 93 MTX used, and it never smelled again!

 

[pjtoledo]

Sounds like something my 92 has always done. When the tank is below 1/4, and the air temp is above 90 I get lots of gas fumes. For me the fix is simple, fill the gas tank. Seems the vapor pressure increases with more volume above the liquid, a full tank puts out less fumes and the evap/purge system can then handle it. TWRSHO mentioned the restrictor insert. If that restrictor is plugged (like it was in my 87 wagon) the engine vacuum will not be able to suck any fumes from the tank, resulting in a pressurized tank. Does your tank pressurize? It shouldn't. Also, do not increase the size of the opening in the restrictor, that will allow too much engine vacuum to reach the tank. Result is a collapsed tank. Keep us posted.

Perry Toledo,Ohio

 

[pjtoledo]

twrsho:
I copied this of of SHOtech - it was a response to what the extra hose that stops at the back of the car behind the rear passenger tire - I believe this might be the reason for the fuel smell back there.

The extra hose may be the fuel vapor recovery "fix" TSB from some years
back. I don't recall the TSB number, but it was a bandaid for a problem
which I believe Ford did not correctly identify.

Many early Tauri had a problem with fuel smell in the passenger
compartment during hot weather with the A/C on. The TSB fix was to
install a 15 foot long hunk of hose from the vapor vent on the Fuel
Vapor Recovery Canister (FVRC) and route the hose back to the rear of
the car, where the fumes would be less noticeable.

I've worked on several Tauri with this fix and have usually found that
the vapor vent solenoid valve between the FVRC and the throttle body
was
not opening, resulting in a saturated FVRC. In some cases, the vapor
vent valve itself was bad (open solenoid coil), in others, the EEC
driver channel for the valve was bad. Seeing as how I helped design
some
of the EEC-IV and V chipset, I went into the schematics and found that
Ford had selected a driver channel which had inadequate protection from
the back EMF generated by the solenoid coil. This back EMF eventually
destroys the driver transistor and renders the vapor vent solenoid
valve
inoperative. The same driver chip was used for the cruise control
vacuum
and vent solenoids, and somebody was smart enough to install catch
diodes in a little wiring harness between the cruise servo and the
engine compartment wiring harness, but the diode was apparently
forgotten on the vapor vent valve.

Check the operation of the vapor vent solenoid. Its hanging in the line
between the FVRC and the port on the forward side of the throttle body.
If its not working, I'd sugggest bypassing it with a short section of
1/4" O.D. copper tubing. Don't remove the red plastic orifice between
the valve and the TB, or there will be too much purge on the canister.

If the FVRC is saturated, the car may idle poorly, or not at all, until
the canister gets cleared out.

Terry

Any idea who the author of that article is? I would like to discuss a low speed stalling problem in my 87 SLO wagon with him. Haven't been able to track this problem down, quite intermittant. Thanks.

Perry Toledo,Ohio

 

[projectSHO89]

That's by Gary Morrell, a regular on the mailing list.

Steve