Pressurized gas tank and gas smell
08-02-2008, 10:47 PM
#1
Le Mans Master
Thread Starter
Pressurized gas tank and gas smell
Last few days when I parked the 85 in the garage, an hour or so later I had a heavy smell of gasoline. Since my gas hot water heater is in there I figured I better air it out. I was at the gas station today and when I pulled off the cap (brand new OEM) there must have been 50PSI in the tank. It took a full 30 seconds or so to vent and there was a ton of pressure.
Any Ideas?
Any Ideas?
08-02-2008, 11:57 PM
#2
Le Mans Master
fumes
I am swatting at flies in the dark here, but this seems reasonable to me.....
sounds like your charcoal cannister may not be venting.
the system is supposed to vent the fuel vapors through the charcoal when you drive, to the manifold,through a vacuum line, and store vapors when you shut it off.
Not sure, but I think there is a vent valve and a purge valve as well.
when you have cool gasoline, and you start it up, when the fuel returns to the tank, it should be warmer and a slightly higher pressure.
The vent valve is supposed to bleed off excess pressure and maintain a low pressure (3-5 psi I think) when the engine is running.
the purge valve is supposed to feed the fuel vapors to the manifold once the engine is started, purging the charcoal.
Possibly that manifold vacuum line is plugged or the vacum hose is cracked
sounds like your charcoal cannister may not be venting.
the system is supposed to vent the fuel vapors through the charcoal when you drive, to the manifold,through a vacuum line, and store vapors when you shut it off.
Not sure, but I think there is a vent valve and a purge valve as well.
when you have cool gasoline, and you start it up, when the fuel returns to the tank, it should be warmer and a slightly higher pressure.
The vent valve is supposed to bleed off excess pressure and maintain a low pressure (3-5 psi I think) when the engine is running.
the purge valve is supposed to feed the fuel vapors to the manifold once the engine is started, purging the charcoal.
Possibly that manifold vacuum line is plugged or the vacum hose is cracked
Last edited by coupeguy2001; 08-03-2008 at 12:02 AM.
08-03-2008, 12:08 AM
#3
Le Mans Master
Thread Starter
I was thinking the cannister, but I will trace the system in FSM and see if something is wierd. I wonder if those canisters are available?
08-03-2008, 12:54 AM
#4
Safety Car
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I am swatting at flies in the dark here, but this seems reasonable to me.....
sounds like your charcoal cannister may not be venting.
the system is supposed to vent the fuel vapors through the charcoal when you drive, to the manifold,through a vacuum line, and store vapors when you shut it off.
Not sure, but I think there is a vent valve and a purge valve as well.
when you have cool gasoline, and you start it up, when the fuel returns to the tank, it should be warmer and a slightly higher pressure.
The vent valve is supposed to bleed off excess pressure and maintain a low pressure (3-5 psi I think) when the engine is running.
the purge valve is supposed to feed the fuel vapors to the manifold once the engine is started, purging the charcoal.
Possibly that manifold vacuum line is plugged or the vacum hose is cracked
sounds like your charcoal cannister may not be venting.
the system is supposed to vent the fuel vapors through the charcoal when you drive, to the manifold,through a vacuum line, and store vapors when you shut it off.
Not sure, but I think there is a vent valve and a purge valve as well.
when you have cool gasoline, and you start it up, when the fuel returns to the tank, it should be warmer and a slightly higher pressure.
The vent valve is supposed to bleed off excess pressure and maintain a low pressure (3-5 psi I think) when the engine is running.
the purge valve is supposed to feed the fuel vapors to the manifold once the engine is started, purging the charcoal.
Possibly that manifold vacuum line is plugged or the vacum hose is cracked
In addition, I think the charcoal purge cycle is the same as EGR, so it will purge when you drive.
If you forget the gas cap after a fill up (or have a weak sealing one), and the purge does it's thing, IT HAS TO HOLD VACUUM AFTER so many seconds of purge - 10, 20, 30, ??, or it will trip 32 code EGR failure.
That's what FSM said about my '87; might or might not be the same for other c4's...
There's a screen in the cannister, a paper element, and charcoal. They're not made serviceable, but for $110, I could make it serviceable. And it will have to be sealed - no RTV, since gasoline solves RTV.
FORGET storing the vapors - route the cannister purge tube (not the tank vent input!!!) into the intake, way up near the filter. IMPROVE YOUR GAS MILEAGE by doing so. Those tank vapors are perfect air/fuel burn mix.
Last edited by schrade; 08-03-2008 at 12:59 AM.
08-03-2008, 02:41 AM
#5
Le Mans Master
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Most likely the line to the canister is blocked.
Pull the vent line off the tank ( under the rubber seal around filler ) and the canister and try to blow through.
If blocked, check the rubber hoses in the drv rear wheel well ; rust from the steel lines falls down there and jams in the rubber hoses where they join the steel lines together
Pull the vent line off the tank ( under the rubber seal around filler ) and the canister and try to blow through.
If blocked, check the rubber hoses in the drv rear wheel well ; rust from the steel lines falls down there and jams in the rubber hoses where they join the steel lines together
Last edited by rodj; 08-03-2008 at 04:00 AM.
