Topic: 20R carb vacuum diagram for an 80 - CA and Canada

[jmac80]

Finally got my carb rebuilt and back on the truck and don't seem to have my vacuum lines right and was hoping someone could post a picture of diagram, either from a manual or from under the hood (mines shows a 22R diagram, so I guess hood was replaced somewhere along the line).

I've seen posts about this here and on Pirate, but those I've found are old and often the images don't work anymore.

After finally receiving a spare and salvaging parts from it that were missing from mine, I put it back on truck.  When replacing some of the old/bad looking vacuum lines, I found a BB stuck in one of the lines....guess it's from a check valve (I was missing one and spring, so perhaps there was part of it).  Anyway, after going off a couple of diagrams on AutoZone website (mine looked to be a hybrid of a CA and a Canada diagram), the truck cranked and surged between 1500 and 2000 rpm until choke opened and warmed up.  After that it wanted to idle at 2500 and would not idle down with either gas/air mix screw or with fast idle adjustment screw.

The reason I'm saying CA/Canada hybrid is because I've got two lines running off the distributor as shown in Autozone Canada diagram but the rest looks more like the California diagram.

https://www.autozone.com/repairguides/Toyota-Celica-Supra-1971-1985-Repair-Guide/VACUUM-DIAGRAMS/VACUUM-DIAGRAMS/_/P-0900c1528007c9f4

Also, I saw that one of our buddies on here had a 80 FSM, and asked him to check it for me.  He sent me what it had, but there was no diagram and told you to look under hood at sticker.

[Toyotadon]

Does this help?



You may also have the wrong distributor or advance unit for the engine.

[jmac80 [OP]]

Does this help?



You may also have the wrong distributor or advance unit for the engine.

That's awesome!  Thank you.  I'm at work now and it's raining off and on so may not get to it this afternoon, but this is WAY easier to read that what I was working with before.

[jmac80 [OP]]

Still having issues getting everything working right.

Most diagrams show 5 ports on the side of the carb be the idle adjustment, choke set, and air/gas mix screws.  Mine only has 4.  There are two on each side of the air/gas mix screw.  Does anybody know which is which?  ....starting to get frustrated with this thing.

[jmac80 [OP]]

Finally got around to messing with this thing some more yesterday.  So it looks like my carb is off a 78 Corolla/Cellica, having the 4 port set up.  For future reference if someone has this issue.  Going left to right (rear of vehicle toward the front) for the Corolla carb, the ports go 1-EGR; 2-Spark control; air/gas mix screw; 3-AI Control; 4-Advancer Port.

So, I'm missing the EGR-R port for this carb.  Anybody got a suggestion of where to hook it up?  Just Y it into the EGR port?....I don't really understand what all of these components do.

Also, the truck diagrams show one of ports as "fuel cut port" whereas the corolla says "spark control port". I hooked my "fuel cut port" line into the "spark control" port....does this sound right.

So, aside from that something else has come up after truck sitting for few weeks.  Now, I'm not getting fuel to carb.  I should be able to pull the fuel inlet from the carb and turn on key and have fuel come out right?  Will the fuel pump run continuously with no back pressure from carb when key is on w/out truck running?

.....and finally, still having the high rpm issue.  I made it run by pouring gas in the top of the carb.  What seals the bottom of the carb and the head to that plastic plate that separates them?  I'm thinking a I may be sucking air in there, but didn't have a gasket in my kit or during removal.

Thanks for help I realize this is not the most interesting topic and I should just buy a Weber instead of trying to keep this old stuff limping along, but I've got time and money invested now and just want to get it rolling again.

[jmac80 [OP]]

the pump is mechanical....i thought that thing was some type of filter  ....showing my true colors here.

so how do we test a mechanical pump?  Do they fail often?  I can hear a slight hissing sound out of the carburetor when NOT running and after trying to pump it up using the accelerator pump on the carb....Could the mechanical pump seal have failed and I hear the gas sucking back down into tank?

[jmac80 [OP]]

the pump is mechanical....i thought that thing was some type of filter  ....showing my true colors here.

so how do we test a mechanical pump?  Do they fail often?  I can hear a slight hissing sound out of the carburetor when NOT running and after trying to pump it up using the accelerator pump on the carb....Could the mechanical pump seal have failed and I hear the gas sucking back down into tank?

Doing a little more research and pulled the/a fuel filter off. I guess there is only one. It's not 100% plugged but I wouldn't call it easy to blow through. I'll get another one tomorrow and see if that fixes issue..... Maybe the pump build up a little vacuum between itself and filter and relief of such was the noise I heard after running it by feeding fuel through the top of carb. Anybody suggest a brand or just get something off shelf at parts store?

Here's the old one.

Also, I saw that image of the 1980 20r vacuum diagram had come down so I took a pic of the printout i had made of it.

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[jmac80 [OP]]

Went with this for $10. I'll try it out tomorrow. Hopefully that's the fuel issue. It's considerably easier to blow through. I'll put the filter side facing the pump to allow larger surface area on tank side where all the crap comes from.

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[fireitup]

Check out https://parts.lakelandtoyota.com/ and type in your vehicle info.  Select "Fuel, Exhaust and Emissions" as the category and all the 20R Carb Assembly Diagrams will be displayed.  They have vacuum hose diagrams as well. You can save off the image files for reference.

You are fine to replace the fuel filter with an inline one.  I started using this one https://www.amazon.com/Mr-Gasket-9706-Universal-Clearview/dp/B00068OR8M/ref=sr_1_5?ie=UTF8&qid=1522255881&sr=8-5&keywords=inline+fuel+filter a while back and it works great.  Also nice to see the fuel flow through the clear housing.

So, aside from that something else has come up after truck sitting for few weeks.  Now, I'm not getting fuel to carb.  I should be able to pull the fuel inlet from the carb and turn on key and have fuel come out right?  Will the fuel pump run continuously with no back pressure from carb when key is on w/out truck running?

If the pump is working and you do that it will spray fuel all over the place.  I don't recommend it.  You should be able to monitor the float bowl level through the sight glass on the front of the carb to tell if you are getting fuel in there.

Also, I recently had some issues with my fuel pump and ended up replacing it. Before you do that though i'd double check that you don't have a kinked/clogged hose somewhere.  Disconnect the fuel inlet hose that goes from the filter to the fuel pump and use a vacuum pump + brake bleeder catch attachment to see if you can draw fuel up to that point.  If you can, reconnect the hose and see if the pump starts working properly.  If it is still not getting fuel into the carb then replace the pump.

.....and finally, still having the high rpm issue.  I made it run by pouring gas in the top of the carb.  What seals the bottom of the carb and the head to that plastic plate that separates them?  I'm thinking a I may be sucking air in there, but didn't have a gasket in my kit or during removal.

I don't think I have a gasket in between the carb and the plastic insulator on my 22R carb.

I just had a similar issue when getting a new replacement carb up and running (http://board.marlincrawler.com/index.php?topic=102904.0).  What i think fixed my issue:
1) Lubricating the fast idle linkage on the back of the carb and ensuring all the cams actuated properly. (assuming your 20R carb has this mess)
2) Possibly E-Choke was not being powered properly.  (I do not think the 20R Carb has this so probably irrelevant)

If there are any vacuum controlled idle up features on the 20R carb then get familiar with them. Make sure everything is doing what it is supposed to do both when the engine is cold and hot.

*edit* Also make sure your AC is not on.  If the compressor is on it will cause the fast idle stuff to kick in.

[Gnarly4X]

What is the GPM flow through that gas filter?

Gnarls.

[fireitup]

the pump is mechanical....i thought that thing was some type of filter  ....showing my true colors here.

so how do we test a mechanical pump?  Do they fail often?  I can hear a slight hissing sound out of the carburetor when NOT running and after trying to pump it up using the accelerator pump on the carb....Could the mechanical pump seal have failed and I hear the gas sucking back down into tank?

I believe the accelerator pump on the carb will only pump fuel from the float bowl into the carb air intake barrel.  The mechanical pump will only function if the camshaft is turning.  Due to the carb fuel inlet location high up on the float bowl, I doubt any fuel is leaking back.  If you had the engine running and just killed it maybe you could hear fuel draining from the pump back into the tank.

That hissing sound is interesting though. Not sure what would be causing it.

From my 83 FSM:

83-FP-1

83-FP-2

83-FP-3

[jmac80 [OP]]

What is the GPM flow through that gas filter?
Gnarls.

That hissing sound is interesting though. Not sure what would be causing it.

Thanks for chiming in fellas and taking the time to put up the fuel pump replacement steps.  I agree with you on the accelerator pump, I don't think it can pull on the inlet.....I think it would just barely pick up remnants of gas out of the nearly empty bowl and that was enough to make it run.  The bowl is nearly empty as I can't see level in sight glass (nice and clean/clear after rebuilding) and can see bottom of bowl being wet with gas but not full of gas when viewing from top with flashlight and opening choke and butterfly.  I think the hissing sound was the release of vacuum being built up between the filter and the pump.

Got home late yesterday and couldn't get the old clamps to fit over hose/metal barb area with filter installed.  I bought some regular hose clamps at lunch today and will clamp hoses and reassess pump this afternoon.  I will also try to listen for leak with vacuum and check out the the diagrams and linkages.  My vote is on a leak somewhere as if it was linkage it should have died when adjusting the air/fule mix screw.....which didn't phase it, 2400rpm at running temp with choke wide open and butterflies closed.  I'm also doubting a crimped line as it went from running to not without doing anything to it but will confirm.  Let me gas going back up there to the SOB, and we can go from there.

Gnarls-   GPM?.....no freaking clue, guess it depends how hard you suck on it.  No but really, it says for carb application on the back of the label and is very easy to blow through.  Its not for a high pressure system even though it's metal.

[fireitup]

My vote is on a leak somewhere as if it was linkage it should have died when adjusting the air/fule mix screw.....which didn't phase it

I actually found the exact opposite to be true.  With the linkage stuck keeping the fast idle engaged, my air/fuel mixture screw did nothing.  That circuit is only relevant when the throttle is fully closed. 

If the throttle is open, then airflow into the engine increases -> venturi sees more airflow -> more fuel is drawn into the carb intake bbl from the primary nozzle = higher rpms/idle mixture screw adjustments are irrelevant.

If the throttle is closed, airflow deceases -> venturi sees little airflow ->  little fuel is drawn into carb intake from primary nozzle = lower rpms/idle mixture screw adjustments become relevant.

I came to these conclusions from the following diagram + the observed behavior of the trail gear 22R carb:



Before figuring out the fast idle issues, i had very similar behavior from my motor.  ~2k RPM idle at operating temp, and adjustments to idle mixture screw did nothing.  After the fast idle cam was unset properly/throttle was able to fully close, rpms dropped and idle/mixture screw adjustments changed idle rpms.

[jmac80 [OP]]

I actually found the exact opposite to be true.  With the linkage stuck keeping the fast idle engaged, my air/fuel mixture screw did nothing.  That circuit is only relevant when the throttle is fully closed. 

If the throttle is open, then airflow into the engine increases -> venturi sees more airflow -> more fuel is drawn into the carb intake bbl from the primary nozzle = higher rpms/idle mixture screw adjustments are irrelevant.

If the throttle is closed, airflow deceases -> venturi sees little airflow ->  little fuel is drawn into carb intake from primary nozzle = lower rpms/idle mixture screw adjustments become relevant.

I came to these conclusions from the following diagram + the observed behavior of the trail gear 22R carb:



Before figuring out the fast idle issues, i had very similar behavior from my motor.  ~2k RPM idle at operating temp, and adjustments to idle mixture screw did nothing.  After the fast idle cam was unset properly/throttle was able to fully close, rpms dropped and idle/mixture screw adjustments changed idle rpms.

OK, so the carb saga continues. I now think my needle valve is stuck. The new one looked different than the old.

So here we go. Put on the new fuel filter and confirmed gas all the up to carb. I tried to blow through the carb inlet line (the one that goes into the banjo fitting). I could not get air to pass and thought that although it didn't matter before that the ignition shutoff solenoid was now shutting off flow. Tried a different one I had on another carb and hooked it directly to battery. Still couldn't blow through inlet tube. Removed the solenoid valve completely and still couldn't get air to pass through by blowing.

Now looking at the diagram above, it looks like the inlet leads to the needle valve and so I'm guessing it's stuck since I know the bowl is empty. Anybody got any tricks for this one?

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[jmac80 [OP]]

New version in bag. I had this pic another post.

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[fireitup]

Now looking at the diagram above, it looks like the inlet leads to the needle valve and so I'm guessing it's stuck since I know the bowl is empty. Anybody got any tricks for this one?

The float bowl cover is only held on by a handful of screws. You should be able to lift it off and pull the whole float/needle assembly out without having to remove the carb from the truck. 

[redneckcustoms13]

Not being a critic, but throw that rock filter in the garbage and get a correct fuel filter. Those are junk. I have watched way too many people chase their ass working on hot rods due to those little filters.

[jmac80 [OP]]

The float bowl cover is only held on by a handful of screws. You should be able to lift it off and pull the whole float/needle assembly out without having to remove the carb from the truck.

Will do...I think it's like 7 or 8 screws if I remember correctly, but not really sure what to look for with both seat and needle being new....maybe it'll be apparent upon inspection.  I checked the whole float and needle valve pretty closely during rebuild, especially because the designs were different on the new one and was considering using it again but went with the new after convincing myself.  The kit was a Walker brand from Orielly.  I may or may not get to it this afternoon but will report back.

throw that rock filter in the garbage and get a correct fuel filter. Those are junk.

What's up with these things? Do they have a tendency to break apart?.....I'll try to clean it and return it before the garbage...still have package w/ receipt in it sitting on counter. 

[redneckcustoms13]

They are so fine that they clog easily without even noticing it. They will appear clean but internally by clogged.

[jmac80 [OP]]

They are so fine that they clog easily without even noticing it. They will appear clean but internally by clogged.

That's why I put the outer portion of the filter pointing upstream.... I know what you mean though, it could still clog look cherry. It's packing not a "filter" per say.

.... Aside from that, I drove the truck around the block today...... So the gas thing was not a stuck needle valve. The old hose between the pump and carb is not in stellar shape and what looked like a piece of hose from reassembly got into line.... Big black chunk of something stuck in the seat. Pulled float and needle valve without completely removing carb.... Not to bad, all vacuum lines stayed attached, removed fuel and water lines only.

Rpm issue was dumbass tax, the AC throttle up screw was all the way in and the idle stop wasn't engaging because the AC idle up was catching it and not letting butterfly close. I swear I looked at this closely before putting carb back on, but obviously something wasn't right here... I may have messed with it in a panic after initial issues upon reinstall....it was running with various incorrect vacuum lines hook up attempts since I didn't realize I have the corolla carb at that time.

Now, if anyone else does this with the corolla carb. I just put a screw in the egr r tube as the corrola carb doesn't have the 5th (or 6th, if for some reason you have a 22 20 r monster). I didn't get it on the interstate and it may fall in its face but it ran up fast to 50 OK on a side street.

Now for a fess up, on a previous post I said my carb got around the ignition solenoid cut off by having the needle pushed in and the outside of the housings crimped to hold it back so that gas flows regardless of ignition. Although the the outside is mashed up pretty good, the needle still moves in and out with the spring back. Mine runs because the little o-ring on the tip of the solenoid is not there let's the in meet the out..... Probably not the safest for 4 by but something to keep in mind if you get stuck somewhere over it.

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[jmac80 [OP]]

Thanks for everyone's help by the way...wouldn't be riding without ya'll

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[fireitup]

Glad you are up and running!