Topic: YACR: Yet Another Carb Rebuild

[Lewis Hein]

Hi all,

So... Some of you have been following my woes with cold starting, pinging, and rough idle. Someone suggested it might be the choke, so I decided to have a look this morning. I got a really nasty surprise when I did.

I looked at the choke. The driver's-side choke plate was closed; the passenger side was open. I dunno... maybe this is normal. I tried twisting the throttle linkage to simulate pumping the gas pedal. The driver's side choke plate moved to close more tightly; the passenger side didn't twitch. There's spring tension that returns the driver's side choke to position when I open it; I can set the passenger side to whatever I please, and it stays there. This seemed a little less normal.

OK -- time for a caveat, one that I give a lot on this forum: I have very little experience with these Toyota engines. But the idea of having one carburetor barrel without a working choke contradicts pics from other rebuild threads on this forum, and just seems utterly contrary to reason.

My provisional conclusion: The same less-than brilliant mechanic who bungled so many other things on this truck has been playing with my carb!

On to the rebuild part: No rebuilding has happened yet. But this rebuild should be an adventure. I going to try to rebuild a carb whose workings I know little about, with some parts I know about (and maybe some I don't) possibly broken or gone, and no other carb to go by. I will buy a replacement if I must, but that's $400 that I really, really, don't want to spend. This rebuild, obviously, is going to involve a lot of learning, and a reasonable amount of fabrication and invention.

[fireitup]

I remember when I first got my truck I was terrified of the carb.  Just now getting into it and it's not nearly as bad as I had anticipated.  Just take tons of pics and label everything in ziploc baggies.  Also having a "cheat sheet" that comes with your rebuild kit (or if not I can PM you a pdf of the one from my thread) is priceless.  It helped me ID everything for the baggies and is useful in guiding you once it comes time to reassemble everything.

Have fun!

 

[H8PVMNT]

That "choke plate" on the drivers side is called the "secondary air valve", it's not really a choke and doesn't have anything to do with the cold start.  It reacts to the engine sucking air when you get into the secondary and lifts the secondary metering needle out of the secondary jet to dump more fuel in.

If your choke (passenger side plate) is limp all the time, that's just what my choke was doing when it fell apart inside.  If you PM me your mailing address I will send you a "carb harness" with the electric choke, fuel cut solenoid and the outer vent control valve.  You might need to put your plug on the end of it because the plug is cracked but everything works as far as I know.  If it works for you send me some coffee beans sometime    .

I am glad you are diving into the carb.  They are not that bad and we are starting to get a good bit of pictures and tech on here.  Post up pictures!

[Lewis Hein [OP]]

I dug more into the choke this morning. It's just weird.

There is a teeny, tiny bit of spring tension, coming from the linkage on the outside of the carb. I can't decide if the spring there is supposed to be wound up one more turn or not.

No matter what I do, the choke won't close more than about halfway. I don't know if this is temperature? It was 50F this morning when I was working on it. Or, is there something wrong with the choke?


Also, I think the accelerator pump may be bad. When I twist the throttle to simulate pumping the accelerator pedal, I have to twist pretty fast to see much spray. And even then, it's just a few droplets. And when it's idling right after startup, I can nearly kill it by pressing the foot feed down fast.

Rumor (AKA USPS tracking) has it that a new-to-me functional carb is coming my way -- old carbs are cheap on eBay. Now, I can have one to run the truck and one to play with.

[H8PVMNT]

It's about 70 here and all my carbs have the choke closed with spring tension. It could be just bound up and crusty, or just bad all together.  You will be glad you got the spare carb.

The accelerator pump should give you a cross between a squirt and a mist, pretty well pronounced it if it's good.

[Lewis Hein [OP]]

It's about 70 here and all my carbs have the choke closed with spring tension. It could be just bound up and crusty, or just bad all together.  You will be glad you got the spare carb.

Hmmm. Sounds like it's time for a more serious look at the choke, as soon as my backup carb arrives. I am pretty sure I'll be glad to have it -- I can then rebuild one at my leisure, "borrow" parts if they are broken, and generally twiddle and tweak to my heart's content.

The accelerator pump should give you a cross between a squirt and a mist, pretty well pronounced it if it's good.

Sounds like mine is about shot. Maybe that's why I have such trouble with pinging when I try to accelerate uphill. In any case, I detect some o-rings and maybe machine shop work in my near future.

[Lewis Hein [OP]]

This morning, besides looking at the choke, I decided it was time to get that high altitude compensation valve fixed. I've read many accounts here of changes in 22R performance with elevation, and I live at 5500 feet. Most of my adventures take me higher rather than lower.

Starting off: This is the unit as I received it. Two ports broken, one with the nipple still in the end of the hose. The hoses from the carb were just hanging loose and open. I plugged the vacuum leaks and resolved to deal with the HAC "sometime". Sometime, it turns out, was May 22nd.


This will become the new nipple.


Turning the nipple part


Then it's flipped around in the chuck and I turn a part to fit the hole.


Drill a 5/64" hole


Cutting some grooves to help the JB-weld stick


JB-weld applied.


Now, wait 24h and see if it worked.

[Lewis Hein [OP]]

OK -- something weird happened to my images. But they're in the right order.

[fireitup]

Machine work on your HAC now that may be a first!!

 

[Lewis Hein [OP]]

Ain't nuthin a country boy like me can't HAC...

[Lewis Hein [OP]]

UPDATE 4-25-17:

My new-to-me carb arrived in the mail today. Here what I've seen on a first glance and casual go-over.

The good:
 - All the parts seem to be there. This is in contrast to my current carb, which is definitely NOT complete.
 - It looks as if it's been rebuilt recently, so I may not need a rebuild kit when I take things off to look.
 - The choke acts a lot more functional than mine.

The bad:
 - The fast-idle cam and cam linkage is present but non-functional; This is because the spring that engages it needed one more turn before it went back on.
 - The secondary air valve is different than my current carb -- it only closes completely when the throttle linkage is moved to simulate gas pedal pump. It never opens completely, either. My current one is closed by default, but can be opened completely and will re-close with spring tension.
 - The throttle linkage is much stiffer than it should be. It turns easily enough, but takes several seconds to spring back to "closed".
 - The carb is full of old, old gasoline -- so old that it smells more like motor oil.

The ugly:
 - The acceleration pump is frozen solid -- won't budge. Fortunately, it is frozen in the position that lets the throttle operate, but this will have to be repaired somehow.

Now, as mentioned there are some things different between these two carbs. Some, I know which one is as should be, but some I do not. I think the linkage on mine that just dangles loose is part of the fast idle setup; It sure doesn't dangle loose on this one. However, some things are less clear.

The questions:
How should that secondary air valve be adjusted, anyway?
Is there any way to fix the acceleration pump?
Is oil lubricant good enough, or will this mix with the gasoline?
How much dis-assembly and re-assembly can I get away with before I have to buy a rebuild kit?

[Gnarly4X]

UPDATE 4-25-17:

My new-to-me carb arrived in the mail today. Here what I've seen on a first glance and casual go-over.

The good:
 - All the parts seem to be there. This is in contrast to my current carb, which is definitely NOT complete.
 - It looks as if it's been rebuilt recently, so I may not need a rebuild kit when I take things off to look.
 - The choke acts a lot more functional than mine.

The bad:
 - The fast-idle cam and cam linkage is present but non-functional; This is because the spring that engages it needed one more turn before it went back on.
 - The secondary air valve is different than my current carb -- it only closes completely when the throttle linkage is moved to simulate gas pedal pump. It never opens completely, either. My current one is closed by default, but can be opened completely and will re-close with spring tension.
 - The throttle linkage is much stiffer than it should be. It turns easily enough, but takes several seconds to spring back to "closed".
 - The carb is full of old, old gasoline -- so old that it smells more like motor oil.

The ugly:
 - The acceleration pump is frozen solid -- won't budge. Fortunately, it is frozen in the position that lets the throttle operate, but this will have to be repaired somehow.

Now, as mentioned there are some things different between these two carbs. Some, I know which one is as should be, but some I do not. I think the linkage on mine that just dangles loose is part of the fast idle setup; It sure doesn't dangle loose on this one. However, some things are less clear.

The questions:
How should that secondary air valve be adjusted, anyway?
Is there any way to fix the acceleration pump?
Is oil lubricant good enough, or will this mix with the gasoline?
How much dis-assembly and re-assembly can I get away with before I have to buy a rebuild kit?

Hey Lewis,

Based on the condition of that carb, I would buy a rebuild kit and completely rebuild it.

Not to speak for him, but as you know we have a 22R carb guru right here on this forum who may be able to provide some expert advice and help.... if you need it.

Gnarls.

[fireitup]

I would rebuild that carb. Just finished with my rebuild and not only did I learn a ton, I'm 100% confident with what is going on with that carb.

Dunno about that secondary air valve, but I'd consult the FSM. I'll look at mine Tuesday when I'm back next to it.

Acceleration pump. Very easy to remove the 4 screws and pop out off. The rebuild kits come with a new diaphragm/piston and boot. The pump arm connected to the housing should move freely and I don't see any reason with lubricating that. No gas should contact it.  The whole thing is driven open by a spring so that should be there as well.

Take it apart and check out out! Also check out my rebuild thread for pics if you want to know what to expect. I'd link it but I don't have it handy.

Sent from my D5803 using Tapatalk

[fireitup]

Sorry for horrible autocorrect grammar ^^

Sent from my D5803 using Tapatalk

[Gnarly4X]

Sorry for horrible autocorrect grammar ^^

Sent from my D5803 using Tapatalk

Great job on your carb rebuild!

Nice that you are concerned about the readability of your posts.  If grammar, punctuation, spelling and English composition were critical aspects of forum participation, most forums on the internet would be in deep shait!

I remember a guy posting on Pirate on a good technical discussion, and he was getting torched because his posts had bad grammar and poor spelling.  The idiots that were flaming him had zero idea that the guy was one the sharpest Toyota  engine builders on the site!

You can't judge a book by its cover.

As Einstein said... "Great genius has always encountered violent opposition from mediocre minds"

Gnarls.

[Lewis Hein [OP]]

It looks like i'm definitely going to have to rebuild this carb before I use it, which is kind of a disappointment as I was hoping to slap it  into the truck and rebuild the other one.

Will any old generic rebuild kit work? I'm looking at one from LCE performance that costs $75 and one from RockAuto that costs $35. Do you know if there is there a meaningful difference? What rebuild kit do all you master carb whisperers use?

Acceleration pump. Very easy to remove the 4 screws and pop out off. The rebuild kits come with a new diaphragm/piston and boot. The pump arm connected to the housing should move freely and I don't see any reason with lubricating that. No gas should contact it.  The whole thing is driven open by a spring so that should be there as well.

I removed the screws already. The spring is there and the arm moves freely, but the diaphragm and piston assembly won't budge.

[Gnarly4X]

Rock Auto and Summit sell SMP (Standard Motor Products), and they are quality products.  You could always call LCE and ask them whose kit they sell.  Typically LCE and 22RE Performance prices are a higher than the large distributors, but they sell good stuff and have good telephone support.

Gnarls.

[fireitup]

I used the rock auto kit and it was good for the price. Haven't actually run it yet though to can't really speak for quality.

I also remember H8PVMNT mentioning a NAPA kit at some point.

Sent from my D5803 using Tapatalk

[Gnarly4X]

As an option to a rebuild....

I'd be tempted to buy this one.

https://www.amazon.com/Mophorn-Carburetor-Toyota-1981-1995-2110035520/dp/B072DWKH7W/ref=sr_1_fkmr1_3?ie=UTF8&qid=1495794389&sr=8-3-fkmr1&keywords=22R+Aisin+Carburetor


Gnarls.

[H8PVMNT]

I like the Napa kit but I think most of them are OK and pretty complete.  I know the Toyota AAP diaphragm is superior but they cost as much as a whole rebuild kit.

[Lewis Hein [OP]]

Update 4-27-17

I spent an afternoon tearing into my "new" carb. Either it's a mess, or my understanding of it is a mess.

As mentioned earlier, the bearings on the primary throttle and on the choke were all gummed up on arrival. I had them all un-gummed and was feeling pretty good about it, when I began to look at the linkage on the throttle side. This is when my afternoon got a whole lot more um.. interesting.

One spring in this mass of machinery does nothing. Two levers have no apparent purpose -- one is hooked from the throttle linkage to the secondary air valve to open it when the throttle is opened. On the carb in my truck, this valve seems to close when the throttle is opened. One lever has a pin in the side looks as if it is supposed to catch in a little hook on the throttle linkage so that the lever can engage the fast-idle cam. However, it doesn't catch in the little hook without manual intervention. The vacuum-powered choke breaker and the bimetal strip choke breaker seem to be redundant -- Based upon my analysis either should, on its own, open the choke and disengage the fast-idle cam.

Opening and closing the throttle does nothing to the fast idle cam or choke on either carb -- there's got to be a piece missing that does this, but I have no idea where it is or what it should look like.

I am fast running out of patience. Maybe I'll just invent and build a manual choke & fast idle setup, put it on this carb, and forget the automatic complications.

[Lewis Hein [OP]]

'Nuther update 4-27-17

I went back out this evening to look at the new carb. Turns out there are not any pieces missing from the carburetor, only pieces missing from my head.

There is a link that comes down from the electric choke rod to push on the fast idle cam. I had it in the triangular hole on the stepped side of the cam -- turns out, this is WRONG. It needs to go on top of the cam itself.

Now that that's fixed, opening the throttle will cause the cam to engage and the choke to close. Manually pulling on the choke breaker will open the choke and pull the fast idle cam out of the way by a couple notches -- maybe even all the way. Also, the mysterious springs and levers now serve some detectable function.

I am now beginning to wonder if this same assembly mistake is afflicting the carburetor in my truck, as it acts just as my new one did when I had the linkage put together wrong. Can I pull the carburetor, look, adjust, and replace it without replacing the thick gasket underneath it? This pickup needs to stay operable and I don't have a spare.

Lewis

[Gnarly4X]

'Nuther update 4-27-17

..... Can I pull the carburetor, look, adjust, and replace it without replacing the thick gasket underneath it? ....

I think that's called the insulator.. and yes you should not have to replace it unless it looks like it won't seal the carb to manifold.  But... it's been awhile since I had my 85 and rebuilt my carb.

Gnarls.

[Plainview]

smear a thin film of grease on both surfaces of the carb to manifold gasket and you should be able to reuse it pretty much indefinitely - as long as you don't over torque the bolts.

[Lewis Hein [OP]]

Welcome, Ladies and Gentlemen to this gripping episode of Lewis' Carburetor Rebuild Our hero, the...
Oh, yeah. Did you want an update on my carb tuning?

I took apart the choke on the carb that is on the truck. Funny thing, on my new carb this assembly is riveted together, while on the truck it is screwed together. I took it apart on the vehicle to see what was up, and couldn't find anything the matter. So I put it back together and twisted the black housing to adjust the choke so it would close properly. The truck started then better than ever before at 40F.

That's the good news. The HAC valve is not such good news. The owner's manual does not show clearly where the hoses are to be routed, so I hooked them up as best as I could. I am almost sure they are wrong; The engine was maybe 50F, but when I went to start it, it fired on the second turn over, but then shook the whole pickup for a couple seconds before it went ahead and ran. I haven't touched the timing, and as far as I know, installing the HAC doesn't change it.

I am left to conclude that the HAC is hooked up wrong. What is right? how do I know when the diagram in the owner's manual is so tiny? Or maybe I should check the timing to see if it moved?

[fireitup]

I'm not one to speak at the moment since my truck is running like  right now, but I did document how my HAC was hooked up prior to taking everything apart.  Check out the first post in my rebuild thread for some pics that pertain to exactly this!

[H8PVMNT]

Hooking up the HAC wrong shouldn't make a huge difference at idle.  You could unhook it completely, plug the vac ports and get it running OK, then hook it back up.  My Haynes manual has the HAC ports lettered and it is hard to read but it was enough to figure it out.  Stare at it for a while, you'll get it .

[Lewis Hein [OP]]

UPDATE 2017-06-15

As a member of the EFI generation, I really didn't have an idea of what my HAC valve was supposed to do, other than (of course) compensate for altitude somehow. After a little bit of reading and staring at the following explanation in the manual, I think I have come up with an answer.

At altitude, the air thins out, containing less oxygen per unit sucked in. However, the default carb is dumb; it just sucks in the same amount of air regardless of O2 content. Thus, an engined tuned perfectly at sea level will be running considerably rich at 5500 feet. It appears that the purpose of the HAC is to compensate for this by letting in additional air to the primary, secondary, and idle circuits. This, in theory, should restore O2/fuel ratio closer to stoichiometric.

It also appears that a similar effect may be achieved by messing with the primary and secondary jets.

Side Note: It seems to me that with an A/F ratio sensor, it should be easy to wire up a little electronic HAC: Basically, it would pump air (or close) into those jets until the A/F ratio hit some preset value. Maybe, we could even build in a little knob on the driver's dash to adjust said preset value.

[Gnarly4X]

On the 22R with a HAC, I believe the HAC mechanically senses barometric pressure – more at sea level, less at 5,500 feet elevation.  I don’t believe the HAC can compensate for air density, relative humidity, or ambient air temperature.

The ECU on a 22RE can make some adjustments to changes in AF created by changes in air density.  However an AF gauge or meter only reads output.

Gnarls.

[Lewis Hein [OP]]

On the 22R with a HAC, I believe the HAC mechanically senses barometric pressure – more at sea level, less at 5,500 feet elevation.  I don’t believe the HAC can compensate for air density, relative humidity, or ambient air temperature.

Well, yes. The HAC senses barometric pressure, but this is (of course) well correlated with air density. Thus, compensating according to barometric pressure compensates for changes air density, except for those due to temperature. Air density change is much bigger with altitude than with temperature than even the wildest temperature swings, so in seems reasonable to say that the HAC compensates for reduced air density. Humidity is, of course, relevant but ignored.