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IVE HAD ENOUGH! Help Me Figure out my Vapor Locking!


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Sometimes as cars get older parts in catalogs get condensed so that they may not be quite right. I would still do a pressure and flow test on the system.  This is coming from someone who owns an 1989 Justy and has seen what people list as proper applications and are far from being the proper ones.

 

Also check (My memory fails me here I may be wrong) if there is a fuel return line and that it is free and clear. Another way around vapor lock in modern (read obd anything) cars is to circulate fuel in the fuel system so it stays cool. Also waht you may think of as a vapor lock issue is more of a fuel starvation issue. 

 

Have you fiddled with the fuel lines or emission controls at all?

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Sometimes as cars get older parts in catalogs get condensed so that they may not be quite right. I would still do a pressure and flow test on the system.  This is coming from someone who owns an 1989 Justy and has seen what people list as proper applications and are far from being the proper ones.

 

Also check (My memory fails me here I may be wrong) if there is a fuel return line and that it is free and clear. Another way around vapor lock in modern (read obd anything) cars is to circulate fuel in the fuel system so it stays cool. Also waht you may think of as a vapor lock issue is more of a fuel starvation issue. 

 

Have you fiddled with the fuel lines or emission controls at all?

 

He said the carb fuel level is in the middle of the sight glass.

Why waste time doing a pressure and flow test?

 

Circulating the fuel does not keep it cool.

Quite the opposite.It warms the fuel.

That is why some modern cars use a returnless system to reduce evaporative emissions

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Have you fiddled with the fuel lines or emission controls at all?

Funny thing about my car is that the previous owner did some electrical modifications. when he was doing that I believe he messed up my ECS system because the light never comes on. As far as fuel lies go, I cleaned out my primary fuel line yesterday

Edited by Sapper 157
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When you rebuilt the carb, did you actually remove the emulsion tubes and clear them? 

 

 

 

 

Ok, Um answer to question 1: Can you remind me where the emulsion tube is? and what exactly it does ? :unsure: I imagine I did clean it because I tried to make sure I cleaned every inch of that

There are 4 emulsion tubes. If you don't know that then you didn't clean them. They are under the top of the carb. 2 are under brass caps, the other 2 come all the way to the top. You need to unscrew them, then clear them out. Garauntee this is a huge part of the problem.

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There are 4 emulsion tubes. If you don't know that then you didn't clean them. They are under the top of the carb. 2 are under brass caps, the other 2 come all the way to the top. You need to unscrew them, then clear them out. Garauntee this is a huge part of the problem.

 

+1

 

I would do this.

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Okay, one problem... I dont know what the tubes look like or where on the carb they are located because neither of my carburetor diagrams show any emulsion tubes. Are they metal tubes or rubber? (im guessing metal)  Are they outside the carb or inside? Your description just doesn't make sense to me. Brass caps? where are the brass caps? thats not in my diagram either. Im guessing I will need to take my carb off to get to them correct.

 

Sorry for the confusion, but im just really perplexed by this carb. 

 

Wait a minute, does the emulsion tube have a bunch of small holes in it? 

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Okay, one problem... I dont know what the tubes look like or where on the carb they are located because neither of my carburetor diagrams show any emulsion tubes. Are they metal tubes or rubber? (im guessing metal)  Are they outside the carb or inside? Your description just doesn't make sense to me. Brass caps? where are the brass caps? thats not in my diagram either. Im guessing I will need to take my carb off to get to them correct.

 

Sorry for the confusion, but im just really perplexed by this carb. 

 

Wait a minute, does the emulsion tube have a bunch of small holes in it? 

Brass tubes. About 3mm in diameter or less. And yes they do have holes in them. The idea is that fuel is pulls up from bottom while air is pulled in through top, this mixes and "emulsifiers" the fuel and air into a mix that is then atomized in then Venturi horns.

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Chuck it and go Weber. I know they $$, but they do pop up used on here. Someone may have one if you ask.

Either way, he will have a carb. So he should develope skills and understanding relating to carbs.

 

Throwing new parts on because you don't understand something is a recipe for further frustration.

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Brass tubes. About 3mm in diameter or less. And yes they do have holes in them. The idea is that fuel is pulls up from bottom while air is pulled in through top, this mixes and "emulsifiers" the fuel and air into a mix that is then atomized in then Venturi horns.

Can I reach them without disassembling the carb? 

Thanks for your patience.  

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If it is #76 it is.

Make sure there is not a small piece of dirt inside.It does not take much.

I understand the confusion.Subaru does not call them emulsion tubes.

 

Check #23 as well

 

Might as well check the secondaries too.74.75

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Well I was afraid you guys would say that. Like I said I cleaned every inch of that carb and I distinctly remember cleaning those tubes. Just to be safe however, I took the top off the carb today and recleaned them. No difference. I do believe it is carb related though, because it was after I rebuilt my carb that the problem got a little better. I'm trying to think of what else it could be.

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Does your tach jump around at all?  These symptoms can also be from a bad bushing in the distributer.  Pop the cap and wiggle the sucker, if there's play, it's a cheap fix with tremendous results.

 

or

Vaccuum leaks?

I can rule out vacuum leaks because I did a gauge test and the meter didnt jump around at all. I'll try the distributer idea though.

 

16 PSI is normal for EA81 vacuum pressure right? 

Edited by Sapper 157
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Well I was afraid you guys would say that. Like I said I cleaned every inch of that carb and I distinctly remember cleaning those tubes. Just to be safe however, I took the top off the carb today and recleaned them. No difference. I do believe it is carb related though, because it was after I rebuilt my carb that the problem got a little better. I'm trying to think of what else it could be.

 

The passageways in the casting that feed the tubes.

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The passageways in the casting that feed the tubes.

 

Yep. cleaned those when I rebuilt the carburetor. 

Did you replace all the soft fuel lines under the car?

Thats a good point. :o No I didnt. And I know they haven't been replaced in the last ten years. I'll get to that.  Even if it that isnt the problem then at least I won't have to worry about those lines for a few more years

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Sapper I had the exact same problem as you on a rebuild of a Mitsubishi Cordia carburator.  When I put it back together I had not aligned perfectly in its place the crossmember that goes across the throttle opening which squirts the gas.  I was still able to put it back with that slight misalignment.  When I took it apart I was able to see it was not sitting well.  The answer is in your putting things back together.

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What is the status of the charcoal canister?  Is it hooked up?

Yes it is hooked up. But im not 100% sure it is actually working because my ECS light has never worked (pervious owner messed with the electrical, and I think that is what the problem is)

 

However,now i'm positive I know what the problem is now, thanks to the help of local subie wizard. Veterans, please excuse my use of wording as I do not know all the technical names, but I think I can explain it: there is a very small angled tube on the side of the carburetor throat, below the choke plate. Its right next to the primary venturi. That little nozzle squirts a small amount of gas, sometimes by itself (when first getting started) and sometimes the Primary Venturi kicks in and and sprays fuel at the same time this nozzle sprays fuel. (like when at half throttle). When this little nozzle is not working, or when the pump assembly that powers it malfunctions, then -- like when starting out in 1st gear-- one would have to gun it so as to fully open the primary barrel so that the little nozzle is not needed anymore. And when going down the highway at half throttle or less, that little nozzle is what supplies the majority of the fuel to the system... so when its not working, the engine is being starved of fuel, hence the jerking. I found a video of a hitachi which is nearly identical to ours on youtube, and you can clearly see that little nozzle spraying a good amount of gas. Mine does not do that. it will sometimes do a drop or two, but no more that that. Here is the link to the video: https://www.youtube.com/watch?v=E1vdYqmY0R4

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