Is there any carburetor connection essential to connect to vacuum

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Dumindu
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My tercel:: 1987 Toyota tercle 4wd DX Wagon 1452CC
Location: Sri Lanka
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Is there any carburetor connection essential to connect to vacuum

Post by Dumindu » Sun Aug 11, 2019 8:24 am

My car is a 1987 Toyota Tercel DX Wagon RHD 1452cc manual driven car. It has a Aisen 2 barrel carburetor.

Only Vacuum connection supplied to the carburetor of my car is Secondary Actuator diaphragm. All the other vacuum ports are capped.

My car doesnt have a TVSV valve. It is difficult to find a TVSV valve for this car. So some of the ports those need a TVSV valve are closed and capped.

Since Sri Lanka is tropical country, AAP pump and the Choke openers are not working. Choke was made to open continuously by winding a wire.

Throttle positioners are also not operating since there isnt any TVSV valve.

Vacuum ports near the idle port are also capped.

Is there any other vacuum port that is essential to supply direct vacuum or TVSV vacuum in order to maintain fuel efficiency ?

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Mark
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My tercel:: 1984 Automatic, 1981 sedan
Location: Victoria, B.C.

Re: Is there any carburetor connection essential to connect to vacuum

Post by Mark » Sun Aug 11, 2019 9:00 pm

Probably the distributor vacuum advance.

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Is there any carburetor connection essential to connect to vacuum

Post by Petros » Mon Aug 12, 2019 10:40 pm

some of the vacuum operated system actually improve fuel ecnomy, and driveablity.

disabling them will result in poor economy, the car is designed to run with these systems in place. It might be worth considering if you can find a used Weber carb of the right size off another small car in your area, and install it without the vacuum systems (the weber carb was design to operate without the vac systems).

you might go to the factory service manual and read up how each of the vac systems operate (it is covered in the fuel system chapter and some of them in the emissions controls chapter). Once you determine how they operate, you can set each system to run fix in the best mode for your typical driving conditions, without the typical sensors and switches for normal operation. that way you should be able to improve the economy and how well it drives for most of your driving conditions.

I have been meaning to work through each system and find this out. So it will to help diagnose system problems, or if part of the system ins malfunctioning, and it would allow me to isolate that system to allow it run properly.
'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: 155
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: Is there any carburetor connection essential to connect to vacuum

Post by Dumindu » Tue Aug 13, 2019 12:09 pm

Thank you for your advice.

My car Distributer vacuum advance have one vacuum connection only. But the FSM shows 2.

http://www.toyodiy.com/parts/p_G_1987_T ... 902.3.html

When there are only a one vacuum line connection, how it should be connected?

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Is there any carburetor connection essential to connect to vacuum

Post by Petros » Tue Aug 13, 2019 9:46 pm

Distributor vac advance should go to intake manifold vacuum, past the carb, but before the intake runners.

you want the distributor vacuum advance to go with manifold pressure: low vac at full throttle (less spark advance at full throttle), and high vac at part throttle, cruise condition (more spark advance at high vac. part throttle position).
'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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