Thermovalve, no Vacuum. WTF?

[HondaBoy]

ok, i have the carb modded without the used of the emission controls. so the vacuum mod. anyway, i've been tinkering around and found that the thermovalve listed as having vacuum ports 17 18 and 19 is not pulling vacuum at all. also, the port on the front of the carb that shows where the secondary puller diaphram connects to is pulling very little vacuum if any at all. got any idea's? maybe just the thermovalve? give me a hint of what that could be if you have an idea. and i have not found any vacuum leaks at all.

so anyone got a clue what could cause those ports to not make vacuum, just randomly? maybe this was happening for a while now, because my car had started pinging and so i had fixed that more or less. but i think the vacuum problem has something to do with it.

[A20A1]

Well before you get all worked up which vacuum line did you test?

#17 may not give vacuum at certain coolant temps
Also I think #18 provides vacuum to #19 via the thermovavle... it's just that #17 may be bleeding it off... now it's only supposed to bleed vacuum at a certain coolant temperature... not bleed all the time.
#19 does not have/supply any vacuum of it's own nor does #17... so you should check if #18 from the choke puller is pulling vacuum... that is the only vacuum line that supplies vacuum to the thermovalve and fast idle unloader....


Otherwise
I think #19 may be tied into some other vacuum.
I wasn't able to work out other possibilities because I removed everything on my carb... I never had any parts to backtrack and make a semi-vacuum removal diagram that included choke, etc.
I never intended for choke to be there.
So yeah I just guessed and assumed that somehow #18 would carry vacuum from the internal passage in the carb... to the choke puller, then thru the thermovalve to the fast idle unloader... but I guess #18 and #19 are seperate...

Hrm... if #19 from the black box goes to both the Charcoal cannister and taps into #19 on it's way from the thermovalve to the fast idle unloader then if you hook up a check valve as depicted in the diagram.. then from the check valve conncet it to one of the two vacuum ports at the back of the carb... they are just above the air fuel mixture screw.
So the vacuum wiring will look like this
"T" Tapped into #19... from the "T" to the "check valve" from the "Check Valve" to the vacuum port at rear of carb.
So maybe it isn't manifold vacuum after all. It's throttle port vacuum.
Yup it does use a "T" fitting after #19 exist the black box... it hits a "T" fitting which splits it up one to feed the charcoal cannister and one to go to the fast idle unloader. Thing is you wont be splitting it.... no will you split it to the EGR control valve. Just run #3 to the check vavle and then to #19.

Numbers in Circles are not vacuum line #'s they are locator numbers that represent the valve, solenoid, or diaphragm then are next to.
The numbers in Squares are the vacuum line number... some are not perfect though.

....

This doesn't make sense... I think the check valve would keep #19 from seeing vacuum from #3... but then vacuum in #19 supplied from #18 is then bled to the throttle port vacuum... since check valve only let vacuum go one way.
if not then I dunno... I'm too tired to think.
Update

[A20A1]

Read my post above... and look at the diagrams if you missed it.

ok, i have the carb modded without the used of the emission controls. so the vacuum mod. anyway, i've been tinkering around and found that the thermovalve listed as having vacuum ports 17 18 and 19 is not pulling vacuum at all. also, the port on the front of the carb that shows where the secondary puller diaphram connects to is pulling very little vacuum if any at all. got any idea's? maybe just the thermovalve? give me a hint of what that could be if you have an idea. and i have not found any vacuum leaks at all.
so anyone got a clue what could cause those ports to not make vacuum, just randomly? maybe this was happening for a while now, because my car had started pinging and so i had fixed that more or less. but i think the vacuum problem has something to do with it.

The secondary diaphragm uses Venturi vacuum.. not manifold vacuum... they are different vacuum sources and so they will shift from low to high vacuum or high to low vacuum as you open the throttle... it also need some engine load. So you need to be actually driving in some cases to nottice any real changes.

Normally as you open the throttle more, manifold vacuum drops and venturi vacuum raises. Open the throttle to WOT quickly to get good visable change on your gauge.

If you have two vacuum gauges you can watch the shift between manifold and venturi... also throttle port vacuum is slightly different.

[A20A1]

I may be backwards... it may allow #3 to provide vacuum to #19 thru the check valve and then...

[HondaBoy]

the port i tried to see if vacuum was existant was 14 now that i'm looking at it. dunno why i thought it was the other one. that is the one that is pulling little or no vacuum, along with the diapram puller port on the carb. the reason i say its not pulling much vacuum is because i used to be able to put my finger over the port and was able to feel it. also hooked up a diaphram puller to see if it would work and it didnt on either port. today, the car ran well until i started it this evening. its running like shit, so tomorrow i'm going to go through all the vacuum ports and see what the hell its up with it, because it started running rough suddenly. i'd expect it to be a vacuum problem by the way its runs. its rough at idle but great at higher rpms and take off just fine. if i cant get the #14 port to pull vacuum i'll tell you about it.

found one problem, it was a busted vacuum cap thats on the port comming up off the maifold. one of the large ones. anyway, that didnt fix #14 and the secondary puller port. they dont pull vacuum at all, not even if its warmed up. i checked for any vacuum leaks but found none. anyone got a clue why those 2 dont work?

[A20A1]

#14 on the carb does not supply vacuum... #14 on the carb needs a direct supply of intake manifold vacuum.... thats why #14 connects to the intake manifold... to supply vacuum thru vacuum line #14 to the port on the carb and then to the power valve.

Where are you connecting your vacuum gauge? I think you are doing it backwards... you're testing the port that uses vacuum... instead of testing the port or vacuum line to the port that is actually supplying the vacuum.
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Just keep this in mind... they only thing you test for vacuum is the intake manifold... or a valve/solenoid that is inbetween the intake manifold and the thing it is supplying vacuum to. Everything else pretty much will not show vacuum.

There are only 3 ventrui vacuum ports on the carb. (these ports will not have high vacuum at idle)
1) #11
2) Secondary Vacuum Supply
3) RED Fuel Vapor Line (BELOW FAST IDLE UNLOADER)

There is only 1 Intake manifold vacuum port on the carb...
1) ...and it's intergrated with the choke puller.

There are 2 throttle port vacuum lines at the rear of the carb
1) #3
2) #7

There are 3 ABC ports on the carb
1) A
2) B
3) C


all other ports use vacuum... they are not the source of vacuum. You can test diaphragms and solenoids and valves to see if they HOLD vacuum... but thats about it.


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Anyways at idle any ventrui vacuum port on the carb will not have vacuum, or it will be very low.

[HondaBoy]

ok, now i know what i'm lookin at because i didnt really pay much attention i guess. i'll post back when i find something else.

[HondaBoy]

i decided to have nothing run through any of the thermovalves that were left connected. i'll keep checking up on everything to make sure its going to run well.

[A20A1]

why not use the thermovalves? they are there for a reason... if you don't use them you might as well take the choke and fast idle and convert to manual choke.

[HondaBoy]

i'm probably gonna just convert to manual choke like you said. i've been wanting to for a while. i might as well do it. the choke makes my car run super rich upon a cold start and smoke a lot. if i could control it then it wouldnt do that. i can do it if i have the air cleaner off.

[A20A1]

The EFE screen helps your car run better on cold start... but you might as well remove the screen though since you're not using it anymore.

[HondaBoy]

i actually think the efe screen thats on there just isnt working anymore. i remember you said something about it a long while back, but i never took it back out or anything. i may just punch it out. do i need to get a new gasket for between the carb and then between the efe plate and maifold? i was mostly wondering if i would need to replace that. i was thinking i could use some rtv sealant. or would that not be good to use on a carb since its near gas?

[A20A1]

Between the carb and the EFE screen I used some sealant there... not sure which kind... I thought it was fuel safe though. I removed the rubber gasket in there, it was hard and dry, then I filled up the groove where the gasket was and then put the rubber gasket back in place.

there is a paper gasket between the efe plate and intake manifold, you can cut one of those from a gasket sheet.

[HondaBoy]

i'll most likely do that. 4 studs on the intake that hold the carb down, are those able to come out and be replaced? i was thinking to put some longer ones and make a spacer for the carb. i'll probably have to also come up with a new air box but thats alright.

[A20A1]

you could add another EFE plate... yes the studs can come out, I used a pair of vise grips..., the evil looking clamping pliers with big teeth.

I would say get longer bolts instead of studs... up to you though.

[HondaBoy]

i figured they'd be able to be taken out fairly easily. that was exactly my idea to just more or less stack the efe plate. possibley epoxy them together so i dont have to worry about any type of air or fuel leak. either way, i think it'll work. i would really like to just use the stock air box for now, but i dont know if that'll clear the hood. i'll go check on that.

barely fits, but the hood should still close. if i took out some of the skeleton portion of the hood it will fit without a problem.