The Snake Pit : Stripping a Late 80's Carburettor
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Slow jet is connected to a hole below the throttle plate so that the engine can idle with the throttle plate in fully closed position. If the slow jet or its circuit is clogged, the engine won't idle.
Did you adjust the idle-mixture screw? It controls the amount of the fuel coming from the slow jet.
Also check for proper choke operation, EBCV (carburetor feedback circuit), and outer-vent control valve (EVAP).
Did you adjust the idle-mixture screw? It controls the amount of the fuel coming from the slow jet.
Also check for proper choke operation, EBCV (carburetor feedback circuit), and outer-vent control valve (EVAP).
Originally Posted By: Gokhan
Originally Posted By: Ducked
Above not quite accurate. It'll start, but not run unless you keep blipping the accelerator. That's what it was doing before.
What would cause this remission-then-relapse pattern?
Probably a problem in the slow-speed circuit, such as idle-mixture-screw adjustment or a blockage but could be many things. It could also be a choke issue (supposed to be slightly open when cold and completely open when hot) but there may be many other reasons, including vacuum leaks, float and needle-valve problems, various emission-control-systems components (EGR, feedback or high-altitude air bleed, etc.), etc.
If the choke checks OK, I recommend you to buy a new carburetor as before since you are having so many problems fixing it.
I think the choke isn't functional, but I think its been like that for quite a long time. Car's been slow to warm up for 2-3 years, but its never cold here so the need for a fully-functional choke is less.
Its a manual choke (I think the Corolla is an automatic?) so you wouldn't think there was much to go wrong, but when I move the lever attached to the choke cable, the choke butterfly doesn't move. Faulty spring?
That lever is linked to another lever which is directly connected to the choke butterfly valve spindle. If I move THAT lever the choke butterfly moves a bit (but not much), and so does the choke cable lever, so there's apparently some kind of one-way ratchet thing going on.
Tried partly blocking the air intake with a notebook as a crude choke substitute, to no effect. Maybe the volume of the air cleaner is too great. I'll try blocking the carb throat (s)directly with the air cleaner off when my battery re-charges.
Tried putting butane in the air cleaner and it did TRY to start, but didn't run for long.
Then my battery flattened.
If I work the accelerator lever while looking down the carb throat I can see movement and fuel in the bottom of smaller/rearmost venturi, so I guess the accelerator pump is at least partly working. Should I be seeing this in the larger (forward) venturi as well?
I'll investigate the choke thing further, though I doubt its the whole problem, and there are lots of dire warning against disassembly in the CD-20 engine manual e.g. "NOTE: Make sure not to disassemble the choke valve and choke shaft"
Originally Posted By: Ducked
Above not quite accurate. It'll start, but not run unless you keep blipping the accelerator. That's what it was doing before.
What would cause this remission-then-relapse pattern?
Probably a problem in the slow-speed circuit, such as idle-mixture-screw adjustment or a blockage but could be many things. It could also be a choke issue (supposed to be slightly open when cold and completely open when hot) but there may be many other reasons, including vacuum leaks, float and needle-valve problems, various emission-control-systems components (EGR, feedback or high-altitude air bleed, etc.), etc.
If the choke checks OK, I recommend you to buy a new carburetor as before since you are having so many problems fixing it.
I think the choke isn't functional, but I think its been like that for quite a long time. Car's been slow to warm up for 2-3 years, but its never cold here so the need for a fully-functional choke is less.
Its a manual choke (I think the Corolla is an automatic?) so you wouldn't think there was much to go wrong, but when I move the lever attached to the choke cable, the choke butterfly doesn't move. Faulty spring?
That lever is linked to another lever which is directly connected to the choke butterfly valve spindle. If I move THAT lever the choke butterfly moves a bit (but not much), and so does the choke cable lever, so there's apparently some kind of one-way ratchet thing going on.
Tried partly blocking the air intake with a notebook as a crude choke substitute, to no effect. Maybe the volume of the air cleaner is too great. I'll try blocking the carb throat (s)directly with the air cleaner off when my battery re-charges.
Tried putting butane in the air cleaner and it did TRY to start, but didn't run for long.
Then my battery flattened.
If I work the accelerator lever while looking down the carb throat I can see movement and fuel in the bottom of smaller/rearmost venturi, so I guess the accelerator pump is at least partly working. Should I be seeing this in the larger (forward) venturi as well?
I'll investigate the choke thing further, though I doubt its the whole problem, and there are lots of dire warning against disassembly in the CD-20 engine manual e.g. "NOTE: Make sure not to disassemble the choke valve and choke shaft"
A bit late, but for future reference. Over years of working with chewed out screws made of cheese in pot metal castings, universally the best way to get them out has been to use a battery operated drill with a low torque limiter setting as a "rattle gun". Just chuck up your bit in there and use it to vibrate the screw out. Not enough tourque to cam out the screw head, but with a bit of persistence I've had very few it would not loosen. As a bonus, when it does come loose the drill whizzes it out.
Originally Posted By: Brad_C
A bit late, but for future reference. Over years of working with chewed out screws made of cheese in pot metal castings, universally the best way to get them out has been to use a battery operated drill with a low torque limiter setting as a "rattle gun". Just chuck up your bit in there and use it to vibrate the screw out. Not enough tourque to cam out the screw head, but with a bit of persistence I've had very few it would not loosen. As a bonus, when it does come loose the drill whizzes it out.
Thanks. Would this thing (that I linked to above) fit that description? Not too expensive.
http://goods.ruten.com.tw/item/show?21305080186330
A bit late, but for future reference. Over years of working with chewed out screws made of cheese in pot metal castings, universally the best way to get them out has been to use a battery operated drill with a low torque limiter setting as a "rattle gun". Just chuck up your bit in there and use it to vibrate the screw out. Not enough tourque to cam out the screw head, but with a bit of persistence I've had very few it would not loosen. As a bonus, when it does come loose the drill whizzes it out.
Thanks. Would this thing (that I linked to above) fit that description? Not too expensive.
http://goods.ruten.com.tw/item/show?21305080186330
I assume these runnability problems occur even after the car is warmed up. In that case the choke isn't an issue. The choke plate should simply stay wide open at all times when warmed up.
Vacuum leaks are a major cause of not idling. The carb could be working perfectly but if there is a vacuum leak you won't be able to run at low rpm off of the idle jets because they can't provide enough gas to meet all that extra air.
The "vacuum advance" on the distributor is also important for making a carb car idle. Actually what it does is retard the timing while idling, and advance it back to normal for driving. With optimum timing, the air and fuel have to go almost to zero to slow down the engine. With retarded timing it will slow down without having to tweak the carb as critically to almost but not quite starve it out.
This whole affair reminds me of the episode of "King of the Hill" where the only thing that convinced Hank to replace his old truck that kept breaking down and/or catching fire, was when it finally stalled on railroad tracks and he could only stand there and watch a train smash it.
Vacuum leaks are a major cause of not idling. The carb could be working perfectly but if there is a vacuum leak you won't be able to run at low rpm off of the idle jets because they can't provide enough gas to meet all that extra air.
The "vacuum advance" on the distributor is also important for making a carb car idle. Actually what it does is retard the timing while idling, and advance it back to normal for driving. With optimum timing, the air and fuel have to go almost to zero to slow down the engine. With retarded timing it will slow down without having to tweak the carb as critically to almost but not quite starve it out.
This whole affair reminds me of the episode of "King of the Hill" where the only thing that convinced Hank to replace his old truck that kept breaking down and/or catching fire, was when it finally stalled on railroad tracks and he could only stand there and watch a train smash it.
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Originally Posted By: mk378
This whole affair reminds me of the episode of "King of the Hill" where the only thing that convinced Hank to replace his old truck that kept breaking down and/or catching fire, was when it finally stalled on railroad tracks and he could only stand there and watch a train smash it.
Yeh, that'd do it.
In this case the train is the six monthly inspection, now due.
This whole affair reminds me of the episode of "King of the Hill" where the only thing that convinced Hank to replace his old truck that kept breaking down and/or catching fire, was when it finally stalled on railroad tracks and he could only stand there and watch a train smash it.
Yeh, that'd do it.
In this case the train is the six monthly inspection, now due.
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I'm probably misunderstanding this, but it doesn't look to me as if the choke COULD work, because the plates movement seems to be restricted to a small angle around the vertical.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
The choke equipped cars on which I have worked required the throttle to be depressed once before the choke plate could close and raise the fast idle cam.
Originally Posted By: Ducked
I'm probably misunderstanding this, but it doesn't look to me as if the choke COULD work, because the plates movement seems to be restricted to a small angle around the vertical.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
Choke must be vertical (fully open) with a hot engine.
With a cold engine, it must be fully closed but it should open slightly in no more than three seconds after the engine is turned on (the engine won't run with a fully closed choke even when cold) and then gradually open more toward the vertical position as the engine warms up.
So, just remove the air-cleaner cover and look to see if the operation is as described above. It's as simple as that. A hot engine will stall with a nearly closed choke and a cold engine will stall with a nearly open choke.
A fully (or nearly fullly) closed choke:
I'm probably misunderstanding this, but it doesn't look to me as if the choke COULD work, because the plates movement seems to be restricted to a small angle around the vertical.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
Choke must be vertical (fully open) with a hot engine.
With a cold engine, it must be fully closed but it should open slightly in no more than three seconds after the engine is turned on (the engine won't run with a fully closed choke even when cold) and then gradually open more toward the vertical position as the engine warms up.
So, just remove the air-cleaner cover and look to see if the operation is as described above. It's as simple as that. A hot engine will stall with a nearly closed choke and a cold engine will stall with a nearly open choke.
A fully (or nearly fullly) closed choke:
Originally Posted By: Gokhan
Originally Posted By: Ducked
I'm probably misunderstanding this, but it doesn't look to me as if the choke COULD work, because the plates movement seems to be restricted to a small angle around the vertical.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
Choke must be vertical (fully open) with a hot engine...
...So, just remove the air-cleaner cover and look to see if the operation is as described above. Its as simple as that.
I have, and it isn't. See words and pictures (of the fully open choke with the choke on, and a cold engine) above.
I think the engine temperature isn't directly relevant here, since this is (mostly, though there's a dash-pot involved with the fast idle) a manual choke, so when its on, it should be closed, and when its off, it should be open.
Its as simple as that. Except it isn't.
Originally Posted By: Ducked
I'm probably misunderstanding this, but it doesn't look to me as if the choke COULD work, because the plates movement seems to be restricted to a small angle around the vertical.
That would imply its been mis-assembled, but I left it alone, and the previous owners had it dealer-maintained by Daihatsu.
Choke must be vertical (fully open) with a hot engine...
...So, just remove the air-cleaner cover and look to see if the operation is as described above. Its as simple as that.
I have, and it isn't. See words and pictures (of the fully open choke with the choke on, and a cold engine) above.
I think the engine temperature isn't directly relevant here, since this is (mostly, though there's a dash-pot involved with the fast idle) a manual choke, so when its on, it should be closed, and when its off, it should be open.
Its as simple as that. Except it isn't.
Well, working the accelerator with the choke "nominally" on got it going. I'd have done that instinctively if I was sitting in the drivers seat, but using the remote switch (see "Colourful Ethnic Starter Switch" thread) I forgot.
Started thus, the engine raced. With the choke "nominally" off it didn't, and had to be kept revved up at about 2000 to keep it going. This perhaps implies that the fast idle function associated with the choke is sort-of-working.
The choke, however, is not, since it doesn't close.
Adjusting the throttle speed screw on the now warm engine I could get the idle down to just over 1000. I took it for a few circuits of the campus and it drove OK (stalled once, but that was probably me.)
I suspect that, so adjusted, it won't run properly and will be difficult to start cold. This MIGHT be good enough to put it through the test, assuming I don't have to hang around and it gets cold. Seems unlikely it'll pass emissions though.
Last time I had trouble I had started it on a good squirt of butane in the air cleaner and had waited until it was apparently idling evenly, so I assumed it was warmed up.
I'm thinking IF liquid butane pooled anywhere (say in the sump) it could store enough to let it run for a while, and then go into cold-engine-undrivable mode when the gas (I MEAN gas, as in..er..gas, not petrol) ran out.
Started thus, the engine raced. With the choke "nominally" off it didn't, and had to be kept revved up at about 2000 to keep it going. This perhaps implies that the fast idle function associated with the choke is sort-of-working.
The choke, however, is not, since it doesn't close.
Adjusting the throttle speed screw on the now warm engine I could get the idle down to just over 1000. I took it for a few circuits of the campus and it drove OK (stalled once, but that was probably me.)
I suspect that, so adjusted, it won't run properly and will be difficult to start cold. This MIGHT be good enough to put it through the test, assuming I don't have to hang around and it gets cold. Seems unlikely it'll pass emissions though.
Last time I had trouble I had started it on a good squirt of butane in the air cleaner and had waited until it was apparently idling evenly, so I assumed it was warmed up.
I'm thinking IF liquid butane pooled anywhere (say in the sump) it could store enough to let it run for a while, and then go into cold-engine-undrivable mode when the gas (I MEAN gas, as in..er..gas, not petrol) ran out.
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Why don't you just buy a new carburetor? It seems to sell for a couple of hundred bucks. You don't seem to make any progress with this.
There doesn't seem to be an Aisan (spelled with "a", not Aisin) 87773 carburetor. 87773 is probably just a date code. Model nos. (five-digit like 16030) are found on a shiny little metal tag attached to one of the screws on the air horn -- probably lost in your case.
What year, model, and trim is this Daihatsu Charade? If this was a popular car in Taiwan, small local carburetor repair shops still should have rebuilt carburetors for it.
What year, model, and trim is this Daihatsu Charade? If this was a popular car in Taiwan, small local carburetor repair shops still should have rebuilt carburetors for it.
OK, so, it's a Daihatsu Charade G11 with the 21100-87773-000 carburetor. Aisan 87773 is correct then. Again, if you can't figure it out, going to a local carburetor shop is probably your best option. Mechanics in those places can rebuild carburetors in their sleep.
Originally Posted By: Gokhan
OK, so, it's a Daihatsu Charade G11 with the 21100-87773-000 carburetor. Aisan 87773 is correct then. Again, if you can't figure it out, going to a local carburetor shop is probably your best option. Mechanics in those places can rebuild carburetors in their sleep.
Not exactly. Its a Daihatsu Skywing, AKA Saphir, which seems to be mostly G11, but has a bit of a mix of parts.
I have the G100 chassis and engine manuals, and the G10 engine manual. The G100 has the CB-23 engine, the G10 has the CB-20 engine. My Chinese owners handbook says the Saphir (the only place I've seen this name used) has the CB-22 engine. I don't know what the differences are and no one else I've asked does either.
The G10 engine manual has more detail on the (well, its) carb, but, where there's a difference for specs I'm guessing the G100 is likely to be closer, since 22 is closer to 23 than it is to 20.
For example: How many turns out to start the idle screw at?
G10 2+1/2,
G100 4+2/4
(Because I've travelled, and been exposed to many vibrant cultures, 4+2/4 as Japlish for 4.5 hardly bothers me at all).
Buying a carb and/or getting a "pro" to look at it remain possible options, though I don't necessarily share your confidence that it'll be simple or straightforward.
There are relatively few surviving carburetted cars here, and far fewer people who'd pay to put a new carb in one, so I'd think the market demand for new replacement carbs will be small. It'd have to be exactly the same model carb to be legal.
I don't know if there is such a thing as a "local carburetor shop". I'd bet not, and I'd also bet that, if there is, it'll be hard to find.
There are still a lot of carburetted motorcycles. These are generally simpler, and I'm told you can get them rebuilt (I've rebuilt a couple myself), but I'm also told you have to hunt around for someone to do it, since most motorcycle mechanics don't like rebuilding them because they can't charge enough for their time.
OK, so, it's a Daihatsu Charade G11 with the 21100-87773-000 carburetor. Aisan 87773 is correct then. Again, if you can't figure it out, going to a local carburetor shop is probably your best option. Mechanics in those places can rebuild carburetors in their sleep.
Not exactly. Its a Daihatsu Skywing, AKA Saphir, which seems to be mostly G11, but has a bit of a mix of parts.
I have the G100 chassis and engine manuals, and the G10 engine manual. The G100 has the CB-23 engine, the G10 has the CB-20 engine. My Chinese owners handbook says the Saphir (the only place I've seen this name used) has the CB-22 engine. I don't know what the differences are and no one else I've asked does either.
The G10 engine manual has more detail on the (well, its) carb, but, where there's a difference for specs I'm guessing the G100 is likely to be closer, since 22 is closer to 23 than it is to 20.
For example: How many turns out to start the idle screw at?
G10 2+1/2,
G100 4+2/4
(Because I've travelled, and been exposed to many vibrant cultures, 4+2/4 as Japlish for 4.5 hardly bothers me at all).
Buying a carb and/or getting a "pro" to look at it remain possible options, though I don't necessarily share your confidence that it'll be simple or straightforward.
There are relatively few surviving carburetted cars here, and far fewer people who'd pay to put a new carb in one, so I'd think the market demand for new replacement carbs will be small. It'd have to be exactly the same model carb to be legal.
I don't know if there is such a thing as a "local carburetor shop". I'd bet not, and I'd also bet that, if there is, it'll be hard to find.
There are still a lot of carburetted motorcycles. These are generally simpler, and I'm told you can get them rebuilt (I've rebuilt a couple myself), but I'm also told you have to hunt around for someone to do it, since most motorcycle mechanics don't like rebuilding them because they can't charge enough for their time.
Most carbs have two idle speed adjustment screws, one to adjust the normal warm engine idle speed and the other to adjust the cold idle speed when the choke is actuated and the fast idle cam is raised. The adjustment screw that touches the fast idle cam on your carb may be adjusted so far in that it is keeping the throttle plate from returning to the normal idle position even when the choke is completely off.
Regarding choke, adjust the manual choke by pulling the cable so that it's in the closed position with a cold engine and in the fully open (vertical) position in a warm or hot engine.
(1) The choke should be fully closed only with a cold engine and when the engine is not running. A fully closed choke will even stall a cold engine. It's only needed to start a cold engine and then it should open immediately to the proper angle (see below) when the engine starts running.
(2) As soon as the engine starts running, the choke should open to about 38 degrees from horizontal when the coolant temperature is below 12 C (Celsius), about 55 degrees from horizontal when the coolant temperature is above 12 C, and 90 degrees from horizontal (fully open in vertical position) when the coolant temperature is above 59 C.
You may need to close the choke first by kicking the gas pedal to the floor once or twice before you start the engine. Otherwise, it can stay in the open position even when you pull the control cable.
Idle mixture, idle speed, and fast-idle speed must be adjusted properly. See this link (click here for the OEM repair manual) for how to do these adjustments on an Aisan 16030 carburetor, as well as other adjustments.
Number of turns for the idle mixture is a coarse adjustment. Idle mixture should be adjusted with a tachometer on a running engine using the lean-drop method. See the link above.
Small local carburetor shops usually collect carburetors from junk yards and rebuild them. If you still cannot figure out what's going on, you can go to one of these places. I am guessing some incorrect adjustment, incorrectly installed or broken part, or some vacuum leak. A hot engine shouldn't stall even around 600 RPM. So, there is something wrong but it's no rocket science.
(1) The choke should be fully closed only with a cold engine and when the engine is not running. A fully closed choke will even stall a cold engine. It's only needed to start a cold engine and then it should open immediately to the proper angle (see below) when the engine starts running.
(2) As soon as the engine starts running, the choke should open to about 38 degrees from horizontal when the coolant temperature is below 12 C (Celsius), about 55 degrees from horizontal when the coolant temperature is above 12 C, and 90 degrees from horizontal (fully open in vertical position) when the coolant temperature is above 59 C.
You may need to close the choke first by kicking the gas pedal to the floor once or twice before you start the engine. Otherwise, it can stay in the open position even when you pull the control cable.
Idle mixture, idle speed, and fast-idle speed must be adjusted properly. See this link (click here for the OEM repair manual) for how to do these adjustments on an Aisan 16030 carburetor, as well as other adjustments.
Number of turns for the idle mixture is a coarse adjustment. Idle mixture should be adjusted with a tachometer on a running engine using the lean-drop method. See the link above.
Small local carburetor shops usually collect carburetors from junk yards and rebuild them. If you still cannot figure out what's going on, you can go to one of these places. I am guessing some incorrect adjustment, incorrectly installed or broken part, or some vacuum leak. A hot engine shouldn't stall even around 600 RPM. So, there is something wrong but it's no rocket science.
Originally Posted By: Gokhan
Small local carburetor shops usually collect carburetors from junk yards and rebuild them. If you still cannot figure out what's going on, you can go to one of these places.
No I can't, because I don't know where they are, assuming they exist.
A "black hand" (mechanic) will know where they are (if they exist), but will have no interest in me dealing with them directly. That's the way it works here, especially if you don't speak the language(s).
Re buying a new/rebuilt carb, that'd be a follow-up, not a substitute, for knowing what (if anything) is wrong with this one.
I'd look pretty silly if I bought a new carb and it turned out to be an ignition problem, as suggested above.
I spent a good portion of Sunday wandering around a distant city looking for a tool shop with poor stock control, that might still have a timing light at the back somewhere.
I had a picture of one, and was considering a poster campaign, like someone looking for a lost cat.
Got the standard blank incomprehension and "meio" from counter staff, but at the last place an old geezer came after me and called me back.
Long wait, then bingo. He looked quite misty-eyed with nostalgia, but it might have been the dust.
Small local carburetor shops usually collect carburetors from junk yards and rebuild them. If you still cannot figure out what's going on, you can go to one of these places.
No I can't, because I don't know where they are, assuming they exist.
A "black hand" (mechanic) will know where they are (if they exist), but will have no interest in me dealing with them directly. That's the way it works here, especially if you don't speak the language(s).
Re buying a new/rebuilt carb, that'd be a follow-up, not a substitute, for knowing what (if anything) is wrong with this one.
I'd look pretty silly if I bought a new carb and it turned out to be an ignition problem, as suggested above.
I spent a good portion of Sunday wandering around a distant city looking for a tool shop with poor stock control, that might still have a timing light at the back somewhere.
I had a picture of one, and was considering a poster campaign, like someone looking for a lost cat.
Got the standard blank incomprehension and "meio" from counter staff, but at the last place an old geezer came after me and called me back.
Long wait, then bingo. He looked quite misty-eyed with nostalgia, but it might have been the dust.
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