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Idling Problem After Vacuum/Emissiond Delete


tannerdanger

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So I just picked up an 86 SR5 (4A-C) and a buddy and me pulled out all the emissions systems and plugged vacuum lines etc, we followed the 84hachi youtube videos and read every guide we could. it runs amazing EXCEPT for now it won't idle and sometimes it wants to rev on its own. We can't figure out why and its driving us nuts. all the vacuum lines are plugged except the distributor line and all that, and my friend things the carb bowl is filling with fuel, he says he thinks it wants to spray fuel in there like crazy if we mess with the choke. Anyone have this experience or know how we can fix this? Any help would be incredible, thanks!

-Tanner-

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my friend things the carb bowl is filling with fuel, he says he thinks it wants to spray fuel in there like crazy if we mess with the choke.

 

I'm not familiar with that motor/carb, but I figure it works like a 4K. Bowl filling is controlled by the needle/seat and float, so maybe you have a needle/seat problem that lets it fill up too much. That would flood it at idle and kill it too.

 

Take the top off and take out the needle/seat and make sure there is no dirt or hair in there.

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OK, so it may not be filling the bowl with fuel and flooding it.

 

There might be a vacuum control of the idle via some vac solenoid you've blocked, or a leak in one of the vac lines that is leaning it out.

 

Is there a vac diaphram on the throttle arm or idle screw pivot??

 

Hopefully someone on here will be a 4AC expert.

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OK, so it may not be filling the bowl with fuel and flooding it.

 

There might be a vacuum control of the idle via some vac solenoid you've blocked, or a leak in one of the vac lines that is leaning it out.

 

Is there a vac diaphram on the throttle arm or idle screw pivot??

 

Hopefully someone on here will be a 4AC expert.

 

 

 

well I watched a few videos by 84hachi on youtube who explained that the only vacuum line you need is to the distributor. I think the diaphragm is on the other side of the carb from the throttle arm and idle screw pivot.

 

http://www.toymods.org.au/forums/tech-conversions/52512-4a-c-engine-manual-need-tappet-clearance-specs.html#post1075357

 

here is a post that shows the stock vacuum lines. we have everything either removed or plugged except for one going to the distributor from the TVSV.

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So the TVSV is the temperature vacuum switching valve that runs the EGR system. It might be varying the vacuum with temperature, depending on which port you used, or it might not be working at all if the other lines are blocked.

 

I think you should use the one shown in yellow, straight from the manifold for manifold vac. Those that are shown in blue are all under the same vac, so any line into there would do.

 

It doesn't seem to have a ported vac, the throttle plate doesn't shut off any line at idle.

 

The red area is in a venturi so it has vac that is proportional to air velocity, not what you want for vac advance.

 

It would be interesting if you connected up the other line on the dizzy vac while you had a timing light on it and found out if it gave vac advance or vac retarding...

post-7544-0-73777100-1316412996_thumb.jpg

Edited by altezzaclub
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Well i havent just hooked it up to the TVSV i've tried lots of places and nothing really changes. and I don't think my problem is the same as in that post because mine won't idle at all but ill check it anyway. My friend suggests we need to drill out the plug for the fuel mixture screw, or whatever that is exactly, and need to mess with that. The guy in the video also suggests doing that but I'm just not sure if thats what would cause it to not idle and die. That might be my next thing to try, after I check the diaphragm.

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Well, it does according to the guy who wrote the article, but only when comig off the choke when cold. He doesn't say what that diaphram is, but it obviously opens and closes a fuel pathway according to a vacuum signal. I assume its an enrichment device for cold running. If you block all the vac lines you will stop it working, and maybe it is now flooding at idle because the vac can't shut it off. Hook that part of the vac circuit back up and see if it solves it.

 

My friend suggests we need to drill out the plug for the fuel mixture screw, or whatever that is exactly, and need to mess with that.

 

Your carb man should have suggested that if it was the solution. If he's talking about a cover over the idle mixture screw that stops people playing with it?? So it is factory set and not needed for tuning?? There must be some other way to adjust idle mixture then.

 

If it is related to blocking the vac hoses, then you'll have to re-connect them all and get it working, then block one at a time and see which one stops it idling. It would pay to Google all those components and find out what each one does. It seems no-one on Rollaclub knows anything about it, so you'll have to solve this one yourself. A retired Toyota mechanic who used to work on those carbs would be the man, your local Toyota dealership might have someone like that.

 

I suppose the big question is... Was it idling perfectly when you got it?? If it was then you can put it back to that state. If it wasn't then the problem could be anywhere in there.

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To idle way high and then to just die if you let the clutch out points to a huge vaccuum leak to me, just in what I've come across in the past.

I certainly wouldn't be drilling out mixture screws, that could get messy real quick.

The polution gear you pulled off didn't have an idle air bypass or something like that. Feeding warm exhaust gas back into the manifold or anything like that. Idle air bypass I've only ever seen on EFI cars, but then the Japs do some pretty complicated stuff with the carbies to try and get a measure of control that most people don't bother with. My experience has told me that it works fien brand new and once it's got some wear/age in it, it's the biggest pile of crud you've ever come across.

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