Not Answered: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

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SinusoidalTendencies
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Not Answered: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by SinusoidalTendencies » Mon May 06, 2019 11:34 pm

//Seeking peer review...there are also questions in the comments below
//will turn into a vacuum guide once validated

So in an effort to more closely examine my vacuum routing to discover other possible explanations for a bit of idle searching, and also why the egr actuator wasn't receiving Vacuum from the tvsv during the warm test i traced the direction of vacuum travel from the ports on the carb through the lines and think the vsv's (one way valves) on the front there where oriented wrong. still wondering if i got the direction of vacuum flow right but if the colour coding on the vsv's is the same then it would appear that Robert's are also pointing the wrong direction in his carb rebuild video. if my theory is correct, this would cause your egr actuator and throttle positioner to not receive any vacuum when those lines become active at the tvsv as the one way valve's wouldn't allow vacuum to be pulled with their current orientation.


still wondering if i'm right though. in the middle of a tear down so i haven't started her with the new vsv orientation.
also happen to be missing the one referred to simply as Jet valve in the fsm that's on the engine side. wondering how much that is effecting things.

what do some of you more seasoned professionals think?

EDIT:
the AS would also be effected along side the TP. the lower vsv should flow towards the egr side (the direction you should be able to blow) so it can suck from the engine side where it routs to the TP and AS valves. the vacuum is coming from the middle port on the engine side and going to the tube connection right next to where that related vsv hooks up. the vacuum sucks back to one of the vacuum operated switches by the EBCV (the right one) and through the vsv to the TP and AS.

the VSV on top (the smaller of the two) i believe receives vacuum from the M port on the TVSV. so it would flow the opposite direction of the bigger one below it. meaning you should be able to blow through it towards the engine and the TVSV. this line goes to the choke opener behind the TP through the one way vsv and over to the egr and the back of the actuator. this line i believe is not active with a cold TVSV, but should come on line once the engine warms sufficiently.


Please correct me if this observation is wrong

EDIT 2:
my bad guys. this is a 3A-C Cal routing
if you do not have a Calif. & Canada 3A-C Engine 4-speed & wagon A/T then your vacuum routing will be different
Last edited by SinusoidalTendencies on Wed May 08, 2019 4:03 pm, edited 2 times in total.
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SinusoidalTendencies
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My tercel:: 87 4wd wagon

Re: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by SinusoidalTendencies » Tue May 07, 2019 2:07 am

also... i have almost no idea what the difference is between the different vacuum ports coming from the carb. except the ones to the EBCV which picks up blow by from the lower of the 2 and puts it back through the upper at the top of the carb intake again.

engine side there is a lower port, which is the one i'm missing the JET valve on, and goes to the choke breaker. a middle port outlined in the original post. and an upper port going to port J on the TVSV. i believe this is where port M and L get their vacuum.

on the egr side of the carb there are 2 lower vacuum ports. one which route routs to a vacuum switch valve going to what i believe is an evap charcoal canister in the very back behind the egr stuff. and one which goes to the front of the egr actuator and the lower vacuum advance port.
and the ports for the EBCV.

would love to understand the vacuum system like the back of my hand so please tell me all you know.
I don't always learn my lesson.
But when i do, it's the hard way.

xirdneh
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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
Location: seabeck, washington, USA

Re: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by xirdneh » Tue May 07, 2019 3:09 pm

i will try to remember to look into that tonite
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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SinusoidalTendencies
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Re: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by SinusoidalTendencies » Tue May 07, 2019 4:16 pm

Especially interested in this one way valve looking thing refereed to as JET in the FSM between the lower engine side vacuum port of the carb and the inner port on the choke breaker valve.
Capture.PNG
Capture2.PNG
What is it? is it a one way valve? or some other kind of valve? passive resistance valve is all i can think of....like this one here below that passes air both ways but at a controlled amount....<maybe it's just broken, i don't know>
IMAG0921[1].jpg
IMAG0923[1].jpg
What's it's part #?
And where can i get one?
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Last edited by SinusoidalTendencies on Wed May 08, 2019 8:42 pm, edited 1 time in total.
I don't always learn my lesson.
But when i do, it's the hard way.

User avatar
SinusoidalTendencies
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Posts: 128
Joined: Thu Sep 06, 2018 12:06 pm
My tercel:: 87 4wd wagon

Re: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by SinusoidalTendencies » Tue May 07, 2019 4:20 pm

If my theory's are right these one way vsv's act to keep an amount of vacuum on one side of them after an amount of vacuum has been applied through them, as air is supposed to flow only one way through them similar to holding your tongue on a line after sucking through it to test a diaphragm valve.
I don't always learn my lesson.
But when i do, it's the hard way.

xirdneh
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Posts: 2005
Joined: Thu Aug 04, 2005 11:38 am
My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
Location: seabeck, washington, USA

Re: Not Answered: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by xirdneh » Fri May 10, 2019 2:17 pm

looking at the front of my two cars there are three that i can see. the large one has color on driverside, smaller one aboove it has color on driverside and the one at the back of the head for the vac adv the color is also on driverside
i did not look at the one in the picture. most of them have been disconnected and plugged on cars i have worked on
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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SinusoidalTendencies
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Re: Not Answered: Direction of vacuum flow & routing? + xerdneh''s carb rebuild video refference

Post by SinusoidalTendencies » Fri May 10, 2019 2:51 pm

hmm.. so just like they where before i changed them. i only have the 2 vsv's on the front of the carb though. no valve on the vac advance, and no JET valve on the choke breaker.

current configuration... colour on passenger side
IMAG0928[1].jpg
refer to original post for full explanation

i feel my theory of direction flow is correct so i will report my finding after testing

Definitely want to find that JET valve. if the vacuum to the choke breaker is supposed to be metered in some way it would probably help the choke to function optimally
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