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FUEL TANK ODOR (Venting Issue?)

 
65JBL454
I love my Chevy Chevette!
Posts: 1
Joined: 08/11
Posted: 08/06/11 12:17 PM

I am new to this site and just purchased a 1965 Bel Air with a 454cid modified (more details if needed after you read my problem):

After I put the car in the garage, I woke up this morning with a STRONG gas smell in the house and in the garage (alot of fumes).  I did check all the fuel lines, electric pump, fuel filter and there are no leaks.  The carb is dry on the outside,when its running it idles just fine and the throttle response is great, but I did notice when I was under the fuel take area a STRONG ODOR and I found what I believe was a open fuel tank vent hose?  Just a black rubber 3/8" hose about 12" long attached to a fitting on the tank and pointing up to the bottom of the floor and tie-wrapped to the frame near the rear-end.  If this is the issue, what could I do to correct this problem (wife not happy and to be honest neiter am I, could this be a hazard)?  I know that the per 1970 cars did vent to the air, but I have owned other 60's muscle cars and never had this problem.  The car does have a non-vent cap.

I had someone tell me to install a "motorcycle fuel vent check valve"????? or put a filter on the end of the hose???  ALso was told to add a vented gas cap and plug the other vent hose????  Just want to make sure the car is safe and correct since it is new to me.

Your help is greately appreciated.

Thanks,
Jack  

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idrivejunk
I mow my lawn and find Chevys
Posts: 5119
Joined: 12/09
Posted: 08/06/11 03:39 PM

If its been a long time since you stashed a carbed car in the garage, you may find that this is just the new normal. The gas is more volatile than it used to be. But it sounds like your system vents to open air, as it is designed to. Short of engineering your own evaporative emissions system (charcoal canister like GM did) I don't know of a way to stop the stink. I went from parking carbed cars in the garage, to an EFI car in 2009. One of the first things I noticed is the house doesn't smell like gas anymore. Some cars around 1970 used a "standpipe" box to control vapors. Basically a vent pipe comes into a box and has a couple more tubes for the gas to fall back into the tank after vapors cool and re-liquify. Ultimately they vent to atmosphere thru the canister, but it slows down the fumes. Maybe something like that could be used.  
idrivejunk

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idrivejunk
I mow my lawn and find Chevys
Posts: 5119
Joined: 12/09
Posted: 08/06/11 03:45 PM

Heres kinda what I'm talking about, from a '72 Olds manual-

Standpipe

Tankpipes  
idrivejunk

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waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 08/06/11 08:16 PM

it is so much easier to install a carbon canister from some car in the junk yard..

swapping on a threaded type later model fuel filler neck.. so you can control the vapors..  there are non vented caps available and ones that have a vacuum check valve both for the threaded type of cap.... so there is no suction built up in the tank..  prevents crushing the tank with vacuum either when the fuel is used or when the engine vacuum is pulling through the carbon canister..

an additional line will need to be run to the front for the purge and for vacuum..    there are MANY ways to do this..  some right .. some wrong.. depending on the type of canister you get...    please..   take some masking tape and a good pen when you go to the junk yard..   write the vin number from the car.. at least the first 13 digits so you can figure out what kind of car it was..   and if the emission label is intact..  note if it's a US federal emission car or a california emission car..


this could also be as easy as installing on of the black fuel filter looking things that are installed in the power brake vacuum hose..    guess what.. those are carbon canisters.. to prevent fumes from getting to the booster and ruining the diaphragm..

on cars equipped with electric fuel pumps..  and carbs..   one can ..  shut off the pump before shutting the motor off. and letting the primary float bowl empty on holleys..   edelbrocks and quadrajets don't have that problem..    it does require you to turn on the pump first..  to fill the bowls..  but that will also reduce the vapors in your garage..

gasoline vapors are EXPLOSIVE if enough build up..    they are heavy.. lay close to the floor..       a water heater pilot or a furnace pilot.. even a drier going on has causes the fumes ignite in a rolling wave across the floor and burn down houses..    got an old computer fan that runs on 120VAC  ..    a dryer duct  wall outlet.. the 2 of them could vent your garage constantly..  or at least till the fan seizes up..  

one additional thing..    Gasoline fumes are NASTY .. they can cause all kinds of illnesses if inhaled..   do you really want your wife and children exposed to them..  there is a big note on the side of most gas pumps. fumes may cause birth defects and cancer..



one last thing to think about..    pressure testing your fuel system.. with a hand pump and an accurate gauge..  no more than 2 POUNDS pressure and thats pushing it.. ..   pinch off the fuel line into the carb..    see if it holds pressure..


mechanical fuel pumps also leak fuel when the diaphragm fails..   is there a cleaner than other areas spot near the fuel pump???


all these are IDEAS...   i am not telling you to do anything.. only offering advice..  

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waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 08/06/11 08:31 PM

the carbon canister also kind of required 2 ports on the carb..    a purge port..  something OTHER than the PCV hook up .. unless you want to install a solenoid valve.. to prevent the fuel vapors from collecting in the crank case..   and you can still use the double fitting PCV for the purge connection..




this can be vacuum operated to shut off flow unless there is ported vacuum applied..



there are just so many ways to go but the carbon canister also prevents liquid fuel from being pulled directly into the carb..  only vapors get through..  

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