If charcoal canister is deleted how to make tank breath ?

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Dumindu
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If charcoal canister is deleted how to make tank breath ?

Post by Dumindu » Fri Jul 05, 2019 5:33 am

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?

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

Post by Petros » Sat Jul 06, 2019 9:01 pm

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)

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

Post by Dumindu » Sat Jul 06, 2019 9:22 pm

Again thank you for your valuable advice.

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

Post by Dumindu » Tue Jul 09, 2019 8:39 pm

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

Post by Petros » Tue Jul 09, 2019 11:06 pm

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)

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

Post by Dumindu » Wed Jul 10, 2019 4:54 am

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)

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

Post by NWMO » Wed Jul 10, 2019 9:38 am

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.

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

Post by Dumindu » Wed Jul 10, 2019 7:00 pm

Thank you very much for your advice.

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

Post by Petros » Wed Jul 10, 2019 8:08 pm

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)

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

Post by Dumindu » Wed Jul 10, 2019 9:29 pm

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

Post by Petros » Thu Jul 11, 2019 12:16 am

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)

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Dumindu
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Posts: 139
Joined: Wed Aug 02, 2017 12:34 pm
My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
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Re: If charcoal canister is deleted how to make tank breath ?

Post by Dumindu » Thu Jul 11, 2019 4:30 am

This is the cap this Tercel is having.

Is there any valve in it?
a4.jpg
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