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Where does the vacuum hose connect?

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Old 01-05-2009, 12:13 PM   #1
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Where does the vacuum hose connect? And why does my gas mileage suck.

I looked it up & if it helps, I'm talking about the hose that comes out of the thermo valve as seen on the vacuum diagram. Not the one that goes to the HAI Diaphram, but the other one. It comes out from under the air filter housing. I just don't want to have a vacuum leak, and I'm still chasing down the reason for my terrible gas mileage. There's obviously a spot for a hose to connect to under there, so I figure I'd better either plug it up or find what it connects to, but I'm curious if it's even something that matters.
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And really I guess what I'm getting at here is really, why is my gas mileage so bad!! 10mpg around town lately (and usually in 4wd), and around 15mpg highway, even with hubs unlocked and in 2hi. Rebuilt engine, tranny, new clutch. I just replaced all but maybe 6 vacuum hoses, and cleaned out my egr valve (and noticed that my vacuum modulator isn't functioning properly, so that's something I need to replace, but it's $80). I have stock gears, 30x9.50 all terrain tires....what else? Air filter's clean. I was told my carb is fine...but I do notice a lot of black crap in my exaust that damn well better not be oil since it's a new engine, but it could be unburnt fuel, right? So what else do I need to check? Brakes for dragging and.....? I don't know.

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Old 01-06-2009, 08:44 AM   #2
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It connects to the "passenger-most" edge of the intake plenum. The connection looks like a bolt with two vacuum lines coming out of it that screws into the plenum. Almost like a Y. Of course I'm telling you how mine is set up, it seems like there are a hundred different setups.
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Old 01-06-2009, 09:10 AM   #3
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No that's what it looks like in the vacuum diagram. There are some other hoses going in & out of it, so I really just need to get off my a** and follow where those hoses go. It really is all there in the diagram...just easier sometimes to ask. I wonder how much it affects my performance? I'll have to fix that soon, good thing vacuum hose is cheap!

I finally found an FSM, too, which should be really helpful. Hopefully it'll get sent out this week or next. Used, so pretty cheap, and hopefully in fairly decent shape.
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Old 01-06-2009, 01:30 PM   #4
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Well...the diagram I'm looking at shows the way you describe, but that diagram is from an '85 online FSM. The hose coming off that "bolt" looking thing goes up and attaches to a spot on the top of my carb which is not shown in the FSM diagram. Maybe I'll take a photo, I don't see it anywhere in the vacuum diagram, but I don't want to just pull it off there, it's obviously supposed to be hooked up to something.



The red x's are things I don't believe my truck has, the light blue line is where I see that hose going to, attached to a metal tube coming off the top of the carb...

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Old 01-06-2009, 05:11 PM   #5
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Mine has several vacuum connections on the carb that are capped off. Four to be exact. Three on the passenger side of the carb and one on the drivers side that is not capped. they are all the ones up at the top of the carb. Mine has the ASV (reed valve), no resonator, No HAC valve, no MC valve, no check valve, no DP and only one large diameter hose coming off of the rear charcoal canister.

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Old 01-07-2009, 07:40 AM   #6
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Cool, sounds like mine. I wanted to get a photo last night but my camera batteries were dead. They're charging now so hopefully I'll get some by lunch. After looking really close at things I found another couple hoses that weren't in the right place (unless it changed between '83 & '85 which it could have, but I've hopefully got someone scanning an '83 vacuum diagram for me), so it wouldn't surprise me if things were messed up.

Thanks a lot.
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Old 01-07-2009, 11:56 AM   #7
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The circled parts are connected by the vacuum hose. That's where my hose that "should" connect to the thermo valve on the air filter housing goes...second photo is a closer-up view of where it goes. What on yours is plugged off? Does anything go to this spot?



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Old 01-07-2009, 04:24 PM   #8
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Mine does not have that curvy inlet tube that it's going into, nor does it have those three hoses that go into the upper inlets on your carb.
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Old 01-08-2009, 07:30 AM   #9
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Doesn't even have them eh? Well shoot. My carb says aisin and has the sight glass so I know it's Toyota but I wonder what year it is...Since your carb is sitting out, can you tell me where the seven (or whatever it is) number digit is on it? I can't find any numbers on mine other than a sideways 13 next to an A. It would be nice to find the correct vacuum diagram for my carb. Thanks a lot.
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Old 01-09-2009, 07:15 AM   #10
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Looks like those three hoses on top of the passenger side go to the HAC, and I guess since you don't have that, it makes sense that you don't have those three. I still wonder about that front one, though..
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Old 01-09-2009, 09:04 AM   #11
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I can't tell from the photo where that one actually goes.
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Old 01-09-2009, 09:37 AM   #12
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The top one I'm wondering about? That one on mine goes where the one from your thermo valve goes, but I'm guessing that's not right.
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4runner, 4x4, 95, asv, auto, carburetor, connect, diagram, hose, lines, modulator, oil, repairing, toyota, vacuum, valve

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