fuel vapor cannister problem
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
fuel vapor cannister problem
I had some fuel odor problems in the garage and of course in the house and was ordered by the higher authority to fix it. I discovered that both vacuum lines from the cannister to the carburetor were GONE. Another surprise.
I went to NAPA and bought the appropriate size vacuum line and a tee for the PCV valve and hooked it up like the Assembly Manual showed. Looked real good. Problem is when I took it for a test drive a couple of days later it ran really rich and smoked for about the first mile or so. The second test ride a couple of days later - same thing. After driving a couple of miles it runs great. I have pulled both vacuum lines from the cannister and neither smell of gas.
Is it even possible for fuel to leak into the cannister while sitting in the garage and then get sucked out into the carb in the first 3 or 4 minutes of running and then refill the next time it sits for a day or so?
Any other ideas?
I went to NAPA and bought the appropriate size vacuum line and a tee for the PCV valve and hooked it up like the Assembly Manual showed. Looked real good. Problem is when I took it for a test drive a couple of days later it ran really rich and smoked for about the first mile or so. The second test ride a couple of days later - same thing. After driving a couple of miles it runs great. I have pulled both vacuum lines from the cannister and neither smell of gas.
Is it even possible for fuel to leak into the cannister while sitting in the garage and then get sucked out into the carb in the first 3 or 4 minutes of running and then refill the next time it sits for a day or so?
Any other ideas?
Melting Slicks
Joined: Dec 2005
Posts: 2,441
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If the vapor separator at the fuel tank is defective, it can allow raw fuel to travel to the vapor canister. I've had this experience, fuel leaked from the bottom of the canister.
The separator is located on the top of the tank driver's side .
The separator is located on the top of the tank driver's side .
Last edited by shafrs3; Nov 13, 2006 at 09:10 PM.
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
I disconnected the lines from the vapor canister to the carb, plugged both the lines and the carb ports and the car runs great. Hook them up again and it runs like . . . well real bad.
Does anyone have or know where I can find any diagrams of how the vapor system actually functions?
shafrs3 - you're probably right about the fuel separator but what I can't figure out is how the fuel gets to the carb.
Does anyone have or know where I can find any diagrams of how the vapor system actually functions?
shafrs3 - you're probably right about the fuel separator but what I can't figure out is how the fuel gets to the carb.
Last edited by Thinpockets; Nov 14, 2006 at 07:25 PM.
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
Going from memory, the purpose of the system is to trap fuel tank vapors and route them to the engine when it is running and store them when it's not, an early emission control system.
The fuel separator is similar to a carburetor float bowl with a float and needle inside. It works by capturing and returning fuel to the tank by closing the needle valve to the vapor vent line and draining fuel back to the tank.
The canister is a storage place for the vapors when the engine is off. There is a vacuum operated valve on top that allows vapors to be ingested into the engine when it's running and closed for storage when it's not. When you first start the engine the valve opens and the accumulated vapors are drawn into the air cleaner.
The fuel separator is similar to a carburetor float bowl with a float and needle inside. It works by capturing and returning fuel to the tank by closing the needle valve to the vapor vent line and draining fuel back to the tank.
The canister is a storage place for the vapors when the engine is off. There is a vacuum operated valve on top that allows vapors to be ingested into the engine when it's running and closed for storage when it's not. When you first start the engine the valve opens and the accumulated vapors are drawn into the air cleaner.
Melting Slicks
Joined: Jul 2004
Posts: 3,304
Likes: 8
From: Avon, Indiana
I see Auto Zone take a beating on this forum, but they have a good web site with lots of repair info and pictures.Go to Auto Zone.com, and input your model year. Then, on the right of the page, click Vehicle Repair Guide. Select Emission Control and Fuel System, then Emission Controls. Finally select Evaporative Emission Controls.
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
Very good information site. Thanks.
It and some other articles have me convinced to replace the canister and filter to store the vapor and not release it all at once. Also I will replace the vapor separator on the tank so there will be less fuel in the canister to convert to vapor.
Thanks to all you guys for the into.
It and some other articles have me convinced to replace the canister and filter to store the vapor and not release it all at once. Also I will replace the vapor separator on the tank so there will be less fuel in the canister to convert to vapor.
Thanks to all you guys for the into.
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Safety Car
Joined: Apr 2001
Posts: 3,581
Likes: 28
From: Spring, Texas
Good info to know, thanks. I recently hooked up my canister by purchasing vac hoses to go from the canister to the carb (was not hooked up when I bought the car). Engine runs a little rough now, so I suspect a small vac leak on the original (34 year old) rubber hoses from the tank to the separator, separator to metal line, etc. Going buy more hose now...
Pro
Joined: May 2005
Posts: 745
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From: Miami Florida
i dont really understand why any of us run this thing anyway. why not just gut it and block it off? once any high performance mods are done cam intake headers etc why run any extra vacuume lines in the first place. the gas cap is vented and any fumes from unburnt gas in the carb will be gone in a few minutes. the truth is that i just broke the little vaccume attachment that sits on the side of the fender and i want to gut it all and put a cooler for the power steering/hydroboost where the cannister is, so air goes through it on its way out the side gill.
Safety Car
Joined: Apr 2001
Posts: 3,581
Likes: 28
From: Spring, Texas
Originally Posted by rastadr
i dont really understand why any of us run this thing anyway. why not just gut it and block it off? once any high performance mods are done cam intake headers etc why run any extra vacuume lines in the first place. the gas cap is vented and any fumes from unburnt gas in the carb will be gone in a few minutes. the truth is that i just broke the little vaccume attachment that sits on the side of the fender and i want to gut it all and put a cooler for the power steering/hydroboost where the cannister is, so air goes through it on its way out the side gill.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Originally Posted by rastadr
i dont really understand why any of us run this thing anyway. why not just gut it and block it off? once any high performance mods are done cam intake headers etc why run any extra vacuume lines in the first place. the gas cap is vented and any fumes from unburnt gas in the carb will be gone in a few minutes. the truth is that i just broke the little vaccume attachment that sits on the side of the fender and i want to gut it all and put a cooler for the power steering/hydroboost where the cannister is, so air goes through it on its way out the side gill.
EEC systems with sealed cap. I plugged my vapor line at the tank and use a vented cap, now.