Rebuilding the Toyota Aisan carburetor - Toyota Nation Forum : Toyota Car and Truck Forums
Older Generations (1969-1987) Specific discussion of the AE86, along with generations 1 through 5.

 
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#1 Old 09-12-2011, 08:17 PM
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Lightbulb Rebuilding the Toyota Aisan carburetor

In this post, I am providing the repair-manual pages, actual photos, and a few warnings if you intend to rebuild your carburetor.

Here is the Fuel System chapter from the 1985 Toyota Corolla FWD Repair Manual for the Aisan carburetors, including 16030.

IMPORTANT: In order for the pages to display correctly, use View --> Page Display --> Two-Up in Adobe Acrobat Reader.

Toyota Corolla 1985 FWD Repair Manual Fuel System (Aisan carburetor, including 16030)

Here are the photos of the rebuild of the 4A-LC Aisan 16030 carburetor of my 1985 Corolla LE (FWD) with US Federal emissions:

Toyota 4A-LC Aisan 16030 carburetor rebuild -- complete teardown

Good luck rebuilding the carburetor.

A few warnings:
  • Get a Great Neck impact drive from Autozone to be able to remove the flange screws without damaging them.
  • Use a quarter-dollar coin in the needle-valve strainer and turn it with pliers.
  • A sawed-off flat screwdriver may be useful for removing jets.
  • You need a very thin-walled 9 mm drive to be able to remove the power piston.
  • Take a photo at every step so that you can put things back correctly.
  • Larger jet is the secondary jet, smaller is the primary.
  • Be very careful not to drill into the idle-mixture screw. Go very slowly. Punch a dot in the exact center of the MAS plug first so that the drill bit will be stable. The screw is only 2 mm under the plug.
  • Use goggles when you use compressed air with carb cleaner so that you don't get it in your eyes.
  • You can use short teflon-tubing pieces to replace broken plastic bushings.
  • Don't damage the cold-mixture heater. They don't make it anymore. It only makes a complete circuit when it's installed and don't incorrectly assume that the heater wire is broken -- it's not.
  • Get the correct flange gaskets if they don't come with the kit. Chances are that they won't. You can also make your own gasket from FEL-PRO sheet gasket material -- readily available and cheap at auto stores -- probably much higher quality than aftermarket gaskets in the kits.
  • Don't overtighten any mounting bolt or screw. if you tighten the gaskets too much, they can start leaking in a few years.


Last edited by Gokhan; 09-12-2011 at 08:19 PM.
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#2 Old 06-29-2012, 10:55 AM
'87 corolla dlx calico
 
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I have #16120 carb fm '87.Am able to get carb with either TPS or without. Cant tell if TPS is really necessary for carbureted engine. Will I cover my bases whether I get one or not ?
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#3 Old 06-29-2012, 11:39 AM
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Lightbulb

The throttle-position switch is found in all Corollas made in August 1985 and up (1986 and newer model years) and not found in the earlier models.

So, yes, you need it in your 87 Corolla. It's only a separate, additional attachment to the carburetor and it doesn't change any mechanical fit. I think all mid-80s Corolla carburetors have the same basic body -- only vacuum lines and jet hole sizes tend to differ. If you don't hook up the throttle-position switch or adjust it properly (there is a separate "low-idle" adjustment screw for the Corolla carburetors with throttle-position switches), you may have engine hesitation, but I am not sure exactly what it does because mine is 85 and doesn't have it and I don't have the emissions manual for 87. There are also various orifices around the throttle that sense the various throttle positions using vacuum lines.

Note that one thing that wildly differs among various minor variants of Corolla carburetors is the flange gaskets. Therefore, make sure to get the correct set of flange gaskets. There are three of them and all tend to vary.




Last edited by Gokhan; 06-29-2012 at 06:59 PM.
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#4 Old 10-20-2014, 08:51 PM
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hi there, i have some questions... my 4af carb with aisan carburetor is hard starting ... i already rebuild the carb but its still hard starting,, could it be possible that because the electric choke is not working? i mean its not even connected to a power source, and the choke breaker valve is leaking, maybe the diaphragm inside it already broken, so i just plugged the vacuum hose the one in the bottom, do i need these two items( namely the electric choke coil and the choke breaker? to work to have an easy start? ... thanks for your reply in advance ....
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#5 Old 10-23-2014, 02:49 PM
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You gave little description of your problem. You didn't tell whether it was a cold- or hot-start problem or whether it was difficult to start or idled too roughly.

The choke valve needs to be closed when the engine is cold. Otherwise, a cold engine won't start with a wide-open choke. Likewise, a warm or hot engine won't start with a closed choke.

Let the engine cool for at least 4 hours or more. Remove the air-cleaner cover and look at the choke position. Pump the accelerator pedal two or four times. This should close the choke entirely and set the fast-idle cam.

Start the engine and look at the choke. It needs to remain closed when you first start (to provide the richest possible starting mixture) and then the choke breaker needs to open it slightly after 2 - 3 seconds (to provide the correct cold mixture). If it opens entirely, there is a problem with the choke opener. If it remains closed entirely, there is a problem with the choke breaker. If it remains closed entirely, the engine will run very roughly or even stall. If it opens fully, it will stall.

There are two diaphragms in the choke breaker. The first one opens the choke slightly after 2 - 3 seconds (only delayed by the plastic jet connected to the choke breaker with a vacuum hose that slows the vacuum passage) and the other one opens the choke further after a few minutes (controlled by TVSV). The choke opener (separate device) opens the choke fully (90 degrees) after full warm-up (controlled by TVSV).

Both the choke breaker and choke opener are controlled by the TVSV valve. If the TVSV valve is faulty, they will not operate correctly. If the choke opener is always opening the choke, disconnect the vacuum hose from the port labeled "M" on the TVSV and plug the port with a vacuum plug. This disables the choke opener as well as the EGR. Then see if the choke valve is still open.

Automatic choke (electric choke) housing/heater/spring hardly go bad and I don't suspect any problem in that part. If you have an adjustable version, you can try adjusting the cold-start mixture by turning it. If it's riveted (not adjustable), choke breaker can't be replaced unless you remove the rivets to take out the automatic-choke housing and then remove the choke breaker.

Choke breaker also has an adjustment screw and make sure that it's in place. Always cover this screw with adhesive silicone. Otherwise, it will fall and get lost, causing a large vacuum leak.

If you are still having problems, check your idle speed, fast-idle speed, float adjustment, and idle-mixture adjustment, as well as for vacuum leaks and improperly connected hoses.
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#6 Old 10-23-2014, 07:34 PM
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hi there, im sorry for not stating it, but its in the cold start being hard starting ... that's a good explanation there, I learn something new ... yesterday I try to fix the choke circuit, I put a power supply to the electric choke and adjust it,, now the choke plate is working, before it was always full open, but my problem is the choke breaker it has a leak in it, so I just plugged the vacuum hose, I bend the metal on the top behind the electric choke so that the choke plate wont fully close, because the choke breaker is useless now, I have to find a replacement for it ... today I will try to start the engine and see if I did the right thing ....

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#7 Old 10-23-2014, 08:09 PM
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good news! ... i just started my engine now i pump the gas pedal and 1 click it started ... not like before that it will take me 5 to 6 times pumping the gas pedal and cranking the engine to start..... problem solved ....
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#8 Old 10-24-2014, 05:04 PM
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It sounds good.

Note that automatic choke (heater/bimetal) closes the choke when there is no current (engine off) and engine is cold. It opens it when the engine is warm or it has been running for a few minutes after cold start (choke housing heated by heater). You can check the fuses if the heater is not working.

Choke breaker has two diaphragms. Mine has the diaphragm A torn. It only gives problem in cold weather -- below approximately 12 C [54 F] -- as diaphragm B kicks in above that temperature. In Philippines, it probably hardly ever goes below 12 C. Also, if the choke-breaker jet is clogged, diaphragm A won't work.

I usually find it useful to kick the pedal after a few seconds during cold start -- it makes the idle smoother. It may be because of my choke-breaker diaphragm A not working.

I did get a brand-new choke breaker but never put it in as I dreaded removing the rivets with the air horn installed on the carburetor.

Here are the relevant OEM repair manual pages that you can read to understand the theory of operation and will help with the repairs:
















Last edited by Gokhan; 10-24-2014 at 05:10 PM.
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#9 Old 10-24-2014, 08:41 PM
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wow that's what im looking for, a manual for my carburetor ...my choke breaker also has leak in diaphragm A, so I just plug it, im not sure if I can find a replacement for that here ... yup the usual temperature here is around 32 deg at the highest during summer and about 21 - 25 degs normally ... when the engine starts the choke plate is slowly opening until it is full open and when I turn off the engine the plate closes and back to its original position, so I think I got it right? .. hey sir, do you have a soft copy (pdf file copy) of the book or manual of the 4af carburetor as like above? I mean the entire or whole book, id like to study it so that it will not be hard to trouble shoot any future problem with my carb .. if you happen to have can you please send it to my email address., its " david.loren31@yahoo.com ....
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#10 Old 10-24-2014, 10:07 PM
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I only have a hard copy of the 1985 Corolla FWD (4A-LC) manual. You can probably buy a hard copy on eBay or through Toyota.

With a warm engine, I believe automatic choke shouldn't fully close when the engine is stopped, as the bimetal should be contracted in a warm automatic-choke housing that is above 30 C (86 F). There may be some adjustment or assembly problem. It only closes when the automatic-choke housing cools down. So, if you can take it apart (it's not riveted), do so and check for incorrect installation. Also, adjust it properly.

Note that the USA models come with riveted automatic-choke housings that aren't removable (easily) and they aren't adjustable. Canada models are removable and adjustable.

Also note that a torn choke-breaker diaphragm A shouldn't cause too much problem in warm temperatures, as diaphragm B will kick in anyway.

See the assembly and adjustment of the automatic-choke housing:




Last edited by Gokhan; 10-24-2014 at 10:46 PM.
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#11 Old 10-24-2014, 10:08 PM
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A warm or hot starting tip for carbureted Toyota engines: Press the accelerator slightly when cranking with a warm or hot engine and release it only after the engine starts running smoothly. You can release the ignition key as soon as the engine starts running. These engines flood a lot when warm or hot, possibly due to a clogged charcoal canister, and this helps greatly.

Note: Don't press the accelerator all the way when cranking with a warm or hot engine as the owners' manual says. This is simply an awfully incorrect instruction that can harm the engine.

Last edited by Gokhan; 10-24-2014 at 10:10 PM.
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#12 Old 10-24-2014, 11:25 PM
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its kinda hard to find that kind of manual here in my place ...and yeah the choke plate does not fully closed, it has a little opening in it , so now its just 1 click and my engine starts right away...how about that charcoal canister? mine is not working, because the wiring connections are gone, id like to know what is this charcoal canister for? is this important or is it ok without it? does it affect my engine? ...
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