If charcoal canister is deleted how to make tank breath ?

How-to's and repair secrets for your 4WD can be found here. Have a question? Ask it in here!
Post Reply
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

My car is a 1987 Toyota Tercel DX Wagon RHD 1452cc manual driven car.

If charcoal canister is deleted how to make tank breathe ?

is there any special method to make them breathe?
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: If charcoal canister is deleted how to make tank breath ?

Post by Petros »

there should be a vent tube or line from the gas tank that used to run into the canister. you want to open it up, perhaps put the open end into a small can, metal or plastic, and mount it on the fire wall or fender, to prevent any liquid fuel condensation from leaking out. put some small holes in the top of the container.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

Again thank you for your valuable advice.
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

According to this diagram of my 1987 Tercel, there is no charcoal canister. Actually my car doesnt have a one. I thought a mechanic had removed that.

http://www.toyodiy.com/parts/p_G_1987_T ... _7701.html
Fuel Tank.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: If charcoal canister is deleted how to make tank breath ?

Post by Petros »

lucky you. looks like it only has a supply and return line in the diagram. it must have a built in venting system, perhaps built into the gas cap.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

It opens up at the corner of the rearmost cross member (behind the right rear wheel). There is a pitted anchor clip (As Mr. Petros instructed to manually make) at the bottom of the corner of the right rear cross member to hold and open the tube.

Is that above mentioned arrangement the built-in vent system ? If not please instruct me that where is the built-in vent system located? How it functions?

I want to know that because I need to observe it to detect the location of the fuel leakage of my car.

That check valve in that diagram does opens to both sides. It seems it is defective. Can that cause the problem?

I purchased a new one. (not yet replaced)
User avatar
NWMO
Highest Ranking Member
Posts: 1615
Joined: Wed May 20, 2015 1:08 pm

Re: If charcoal canister is deleted how to make tank breath ?

Post by NWMO »

Dumindu,

Based on a review of the provided drawing, I believe the portion of the line including the check valve is provided to allow air INTAKE into the fuel tank as fuel is removed. The second (shorter) side appears to be the "vent" that would keep pressure from building in the tank. With no check valve on the second side, I assume the "vent" set-up is pinched or otherwise restricted, as minimal flow of air would be necessary to relieve pressure as it builds and you don't want misc. crap coming in. The INTAKE side must be provided to allow sufficient air IN to avoid a vacuum in the tank as fuel is removed at approximately 2-3 gallons/hr.

I would not expect the vent tube to be associated with any leaks, as it carries air and fumes, no liquid fuel should get in that line.

In my experience, a "wooshing" noise when the fuel cap is removed indicates a vacuum in the fuel tank (not pressure). Changing the check valve and making sure that line is clear should help with that.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

Thank you very much for your advice.
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: If charcoal canister is deleted how to make tank breath ?

Post by Petros »

looking at the system I would say the tank vent system is where the "valve" # 77701T is located, where it vents into the item labled "B" with a string of numbers. three lines come off the top of the tank, one is fuel supply, the other is fuel return, third must be the vent.

it needs to be vented to allow the consumption of fuel (as the level drops in the lank it will become a vacuum unless air is allowed in), that is usually through the gasoline cap. but when cold fuel in the tank warms up during the day it could create too much pressure in the tank, causes flooding when you start the car, so there has to be a way to release the excess pressure. with the carbon filter that is released into the engine intake so the vapor is burned off. on older cars, or where there are no emissions requirements, they would just vent it to the air in a way that only vapor can escape.

It may just be gummed up with fuel deposited, take the check valve and the end vent and clean them in solvent, see if they work. verify vent lines are clear to the tank.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

Thank you very much.

Item "B" is the pitted clip as I mentioned above. Its name is "Fuel Emission Tube No 2"
a3 (3).jpg
Should check valve (77701T) open towards the atmosphere or towards the tank?
(I have purchased a new one but doesnt know the opening direction)

Tank cap doesnt have a ventilation hole or any system. It is a simple one. I am having the one of the same OEM part of this vehicle.

Can that 77254 tube have a vetilation function (as Mr. Chris adviced)?
Its name is "Fuel Emission Tube No 1"
a2 (1).jpg
Can both air in and the gas vapor out happens from an one tank tube which is divided as below ?
frame_apngframe0.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
Petros
Highest Ranking Member
Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: If charcoal canister is deleted how to make tank breath ?

Post by Petros »

not sure, hard to tell. your system is different than north American version, so I can not just craw under my Tercel and check.

Usually the gas cap has a one way check valve in it, I think allows air in, but not out. it is built-into the housing, not obvious when you look at it.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
User avatar
Dumindu
Top Notch Member
Posts: 227
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
Contact:

Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu »

This is the cap this Tercel is having.

Is there any valve in it?
a4.jpg
You do not have the required permissions to view the files attached to this post.
Post Reply