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Vacuum Line to carb heaven


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8 replies to this topic

#1 soobiefreak85

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Posted 29 September 2012 - 10:42 AM

So I got 2 air control valves,

One with: 2 ports, one large, one small, pointing opposite of each other (not in pictures)

Second with: 4 ports, all large, three pointing one direction, 1 pointing the opposite (in pictures)

Also I have a, looks like a solenoid valve with 2 small ports (in pictures)

I had it running great, however, it was at a higher idle. So, I started playing with this stuff, bad mistake. I eliminated the charcoal canister. I still have the Anti afterburn valve and EGR. I have taken the lines off the carb and air control valves and got them and rearranged and all mixed up.

What do I do? What can I cap? what is needed? I do I get this routed right? Any diagrams or pictures you have? I looked in the haynes manual and searched this diagram, no luck on routing diagram

Sometimes is starts right away, runs decent (when hot). Seems to starts every time cold and run decent. Weird huh, normally its opposite in most cars

Check out the pics, how do get this routed right, so it will start every time hot or cold. If you pics of your engine bay while explain, that would most helpful. Thanks in advance.

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#2 Idasho

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Posted 29 September 2012 - 10:50 AM

Good luck.

Ive been through this, time and time again, and the resulting fix was a Weber swap.

I while back I started a similar thread, and a few posts down I posted links to other forum threads that had some info...

http://www.ultimates...ad.php?t=118017


Not much to go on when you have no idea how to test each and every component toed to the mess of vac lines :o

#3 Gloyale

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Posted 29 September 2012 - 12:14 PM

Ditch the anti-afterburn. Plug the big port off the EGR that goes to it.

Also, I'm seeing a blue "T" fitting that should have a cap.


One thing to help from getting confused, is you aren't actually working with Vacuum lines. O.K. a few are, but mostly the issue is with the Air Bleed lines for the carb.

Neither of them should be connected to a vacuum source. The air control valve has a vac line to it, to operate a valve.....but vacuum doesn't actually pull "through" it to the air bleeds. You see? The Air bleeds just need to be open to atmosphere, through an orifice.

Try bypassing that air temp vavle mounted to the top of the carb.

I'll see if I can get some better explanation.

#4 soobiefreak85

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Posted 29 September 2012 - 06:49 PM

Good luck.

Ive been through this, time and time again, and the resulting fix was a Weber swap.

I while back I started a similar thread, and a few posts down I posted links to other forum threads that had some info...

http://www.ultimates...ad.php?t=118017


Not much to go on when you have no idea how to test each and every component toed to the mess of vac lines :o


Hey man, read over your past post...boy I feel ya. I am about to drop the money on a weber, so frustrated. It was helpful though, I got a few lines on there right (at least I think). It is running smoother and starting quicker and most importantly starting almost every time. Before, it seemed more often than not it wouldnt start, and would almost never start when up to operating temp. Now, if I shut it off after reaching operating temp, sometimes it wont start....so its getting better. Before it was most of the time...now its sometimes :horse:

#5 djellum

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Posted 29 September 2012 - 06:49 PM

First off, check if you have an O2 sensor plugged into the exhaust at the Y where it goes to 1 pipe. if you do have an o2 sensor wired there, disregard everything anyone has told you in posts and start searching for "hitachi Feedback carb". if you dont have a sensor, keep reading.

Second, if you eliminated the charcoal canister then you probably plugged or otherwise messed up the bowl vent. you will get erratic behavior from that because the carb needs to be able to both pull air into and vent air out of that port. its one of the only thngs you actually need and it needs to be open to vent, but mine needed to be somewhat restricted to run right.

On the front there are 2 hoses that go towords the passenger side. one looks like a match to the gas dribbler on the back, just plug it. the big one on the corner is the bowl vent. this used to go to the charcoal canister, but if you took it out you need to make sure you didnt plug the hose. just open didnt run right for me, plugging it didnt run right, I tried cutting a small hole in a plug which was better, but the best for me was to cram a slightly smaller hose onto it and leave the hose long to add just a little restriction. right now mine is about 2-3 ft long runs around the carb and is plugged into the airbox.

I have everything pulled off of mine and it runs well. I average 28 mpg, starts well, drives fine, idles even when cold with no choke, doesnt smell. Im sure it could be better, but im perfectly happy with it till I can get something better worked out.

on the back driver side of the carb you will have 3 hoses going to the firewall. one is the fuel line, one is the return line, one (that actually goes to the airbox) that is a tank vent. keep both fuel lines hooked up and dont reverse them, dont plug the tank vent. tank vent can be open atmosphere or routed to the airbox or something. I did airbox so I dont get any gas smells around my compartment.

on the back side of the carb faceing the passenger side is some kind of vent that dribbles gas. i have mine plugged off and it works fine. I had it routed different places but the raw gas coming out of it just caused issues. havent had issues since it is plugged. plug it tight or you will have a gas leak.

back passenger side of the carb is a vacuum for the secondary canister and some for the choke. Disconnect the choke and plug the lines, make sure the top butterfly is fully open. if needs be give it the Camaro treatment and wire it open. once you get it running right you can reistall the choke stuff and check it, but for now just disable it so its not causing problems if its faulty. check the secondary canister to make sure there are no leaks and that it is plugged in (nipple kind of hides under the linkage).

Front of the carb should have 4 vacuum ports. 2 on the very front, one at the base in the middle, and one tucked under the linkage on the passenger side. some are ported and some arent, but use whatever is appropriate to hook up your vacuum advance, AC, or whatever other accessories you want. Plug the rest, dont worry about the valves and solenoids. dont remvoe them yet, but just mark where they go and disconnect and plug them. you can always just plug them in again if needed.

As stated above, remove the lines for the antiafterfire valve, and plug them off. also check the small vacuum line on the EGR.

Long story short you need to make sure your fuel delivery is correct, your bowl vent is adequate, and all the vacuum leaks are taken care of. then you can tune the carb and it will work, or at least show its not the problem.

#6 soobiefreak85

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Posted 29 September 2012 - 07:00 PM

Ditch the anti-afterburn. Plug the big port off the EGR that goes to it.

Also, I'm seeing a blue "T" fitting that should have a cap.


One thing to help from getting confused, is you aren't actually working with Vacuum lines. O.K. a few are, but mostly the issue is with the Air Bleed lines for the carb.

Neither of them should be connected to a vacuum source. The air control valve has a vac line to it, to operate a valve.....but vacuum doesn't actually pull "through" it to the air bleeds. You see? The Air bleeds just need to be open to atmosphere, through an orifice.

Try bypassing that air temp vavle mounted to the top of the carb.

I'll see if I can get some better explanation.


I took your suggestions and eliminated that AAV, arranged the lines on the air control valve so they tapped into the carb and the only vac source is the smaller line. It is running better and starting quicker, however, at times it is not starting after it gets up to operating temp...so its getting better. If I bypass the air temp valve it stumbles, so I plugged it back in.

Just noticed, I have a small leak in the carb gasket, maybe that is the culprit for it not starting sometimes at operating temp.

:banghead:

#7 djellum

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Posted 29 September 2012 - 07:26 PM

Edit - looks like you have an EA81, thought it was an EA82. Should still be much the same, but which side the ports face and where your canister was and such might be a little different. theory should be the same though.

First off, check if you have an O2 sensor plugged into the exhaust at the Y where it goes to 1 pipe. if you do have an o2 sensor wired there, disregard everything anyone has told you in posts and start searching for "hitachi Feedback carb". if you dont have a sensor, keep reading.

Second, if you eliminated the charcoal canister then you probably plugged or otherwise messed up the bowl vent. you will get erratic behavior from that because the carb needs to be able to both pull air into and vent air out of that port. its one of the only thngs you actually need and it needs to be open to vent, but mine needed to be somewhat restricted to run right.

On the front there are 2 hoses that go towords the passenger side. one looks like a match to the gas dribbler on the back, just plug it. the big one on the corner is the bowl vent. this used to go to the charcoal canister, but if you took it out you need to make sure you didnt plug the hose. just open didnt run right for me, plugging it didnt run right, I tried cutting a small hole in a plug which was better, but the best for me was to cram a slightly smaller hose onto it and leave the hose long to add just a little restriction. right now mine is about 2-3 ft long runs around the carb and is plugged into the airbox.

I have everything pulled off of mine and it runs well. I average 28 mpg, starts well, drives fine, idles even when cold with no choke, doesnt smell. Im sure it could be better, but im perfectly happy with it till I can get something better worked out.

on the back driver side of the carb you will have 3 hoses going to the firewall. one is the fuel line, one is the return line, one (that actually goes to the airbox) that is a tank vent. keep both fuel lines hooked up and dont reverse them, dont plug the tank vent. tank vent can be open atmosphere or routed to the airbox or something. I did airbox so I dont get any gas smells around my compartment.

on the back side of the carb faceing the passenger side is some kind of vent that dribbles gas. i have mine plugged off and it works fine. I had it routed different places but the raw gas coming out of it just caused issues. havent had issues since it is plugged. plug it tight or you will have a gas leak.

back passenger side of the carb is a vacuum for the secondary canister and some for the choke. Disconnect the choke and plug the lines, make sure the top butterfly is fully open. if needs be give it the Camaro treatment and wire it open. once you get it running right you can reistall the choke stuff and check it, but for now just disable it so its not causing problems if its faulty. check the secondary canister to make sure there are no leaks and that it is plugged in (nipple kind of hides under the linkage).

Front of the carb should have 4 vacuum ports. 2 on the very front, one at the base in the middle, and one tucked under the linkage on the passenger side. some are ported and some arent, but use whatever is appropriate to hook up your vacuum advance, AC, or whatever other accessories you want. Plug the rest, dont worry about the valves and solenoids. dont remvoe them yet, but just mark where they go and disconnect and plug them. you can always just plug them in again if needed.

As stated above, remove the lines for the antiafterfire valve, and plug them off. also check the small vacuum line on the EGR.

Long story short you need to make sure your fuel delivery is correct, your bowl vent is adequate, and all the vacuum leaks are taken care of. then you can tune the carb and it will work, or at least show its not the problem.

Edited by djellum, 29 September 2012 - 07:29 PM.
different engine.


#8 soobiefreak85

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Posted 29 September 2012 - 07:27 PM

First off, check if you have an O2 sensor plugged into the exhaust at the Y where it goes to 1 pipe. if you do have an o2 sensor wired there, disregard everything anyone has told you in posts and start searching for "hitachi Feedback carb". if you dont have a sensor, keep reading.

Second, if you eliminated the charcoal canister then you probably plugged or otherwise messed up the bowl vent. you will get erratic behavior from that because the carb needs to be able to both pull air into and vent air out of that port. its one of the only thngs you actually need and it needs to be open to vent, but mine needed to be somewhat restricted to run right.

On the front there are 2 hoses that go towords the passenger side. one looks like a match to the gas dribbler on the back, just plug it. the big one on the corner is the bowl vent. this used to go to the charcoal canister, but if you took it out you need to make sure you didnt plug the hose. just open didnt run right for me, plugging it didnt run right, I tried cutting a small hole in a plug which was better, but the best for me was to cram a slightly smaller hose onto it and leave the hose long to add just a little restriction. right now mine is about 2-3 ft long runs around the carb and is plugged into the airbox.

I have everything pulled off of mine and it runs well. I average 28 mpg, starts well, drives fine, idles even when cold with no choke, doesnt smell. Im sure it could be better, but im perfectly happy with it till I can get something better worked out.

on the back driver side of the carb you will have 3 hoses going to the firewall. one is the fuel line, one is the return line, one (that actually goes to the airbox) that is a tank vent. keep both fuel lines hooked up and dont reverse them, dont plug the tank vent. tank vent can be open atmosphere or routed to the airbox or something. I did airbox so I dont get any gas smells around my compartment.

on the back side of the carb faceing the passenger side is some kind of vent that dribbles gas. i have mine plugged off and it works fine. I had it routed different places but the raw gas coming out of it just caused issues. havent had issues since it is plugged. plug it tight or you will have a gas leak.

back passenger side of the carb is a vacuum for the secondary canister and some for the choke. Disconnect the choke and plug the lines, make sure the top butterfly is fully open. if needs be give it the Camaro treatment and wire it open. once you get it running right you can reistall the choke stuff and check it, but for now just disable it so its not causing problems if its faulty. check the secondary canister to make sure there are no leaks and that it is plugged in (nipple kind of hides under the linkage).

Front of the carb should have 4 vacuum ports. 2 on the very front, one at the base in the middle, and one tucked under the linkage on the passenger side. some are ported and some arent, but use whatever is appropriate to hook up your vacuum advance, AC, or whatever other accessories you want. Plug the rest, dont worry about the valves and solenoids. dont remvoe them yet, but just mark where they go and disconnect and plug them. you can always just plug them in again if needed.

As stated above, remove the lines for the antiafterfire valve, and plug them off. also check the small vacuum line on the EGR.

Long story short you need to make sure your fuel delivery is correct, your bowl vent is adequate, and all the vacuum leaks are taken care of. then you can tune the carb and it will work, or at least show its not the problem.


This is great info, thank you.

I do not have an O2 sensor. I did plug off the charcoal canister line off the carb and hard line that returns to the tank near the brake booster. I will unplug them tomorrow and maybe restrict the one off the carb if needed, like you had to do.

I think you are talking about a different carb, none of my vac lines on the carb are pointing towards the pass side, most are pointing towards drivers side. Mine is an 1987 hatchback, ea81. I got the fuel lines hooked up right, just working with the other mess.

#9 djellum

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Posted 29 September 2012 - 11:53 PM

there are differences in the carb, but they are the same one. both are hitachi's. there is a carter version on some cars, but yours looks just like mine pretty much. the differences are due to other equipment like the charcoal canister being on the opposite side, distributor in front, etc. you may find some external port differences, or some internal parts smaller, but the basic operation will be the same.

either way the stuff we are dealing with are basic carb items.

the basic operation will be that the fuel comes in from the tank, and the return line allows for the pump to run without fuel pouring into the carb. when the motor is on it pulls in what it needs and the return line allows extra to return to the tank. the tank vent keeps the pressure in the tank regulated to allow the car to use what it needs without starving or chokeing on it. not all cars are set up this way, but yours is from the look of it.

the bowl vent works the same way. the vent allows the carb to maintain the proper pressure in the bowl. that way the carb gets exactly how much fuel it asks for instead of getting it forced or restrained by pressures.

when these get messed up, the car starves, or chokes, or both depending on what your trying to do. you may also see variations on hot days when the tank pressure is higher, at operating temperatures when mixtures change, rev's and stalls when turning and other signs.




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