Tercel 3A Carburator

[Bad-4-Toyota]

Hi Members!
I have been having lot's of carb issues with my 83 Tercel 3A Carburetor. My carb works some what, it idles at 2000; if I go lower it stops. When I shut off the engine it won't start until it cools! And it won't start up cold unless I pump the heck out of it. I checked the fuel pump, and it's OK. Now I would like to know is: what can I do to fix this carb? Is there something I need or maybe fix? Please help!
Thanks a Ton!

[dlb]

hi bad-4-toyota. you said the engine idles at 2000 pm but dies if you go lower than that. are you holding the throttle open to keep the revs at 2000 or have you adjusted the idle speed screw so that it always idles that high? besides the weird idle and starting issues, does the engine run ok?

i would first check and adjust the idle speed, fast idle, and throttle positioner screws. then i would check the choke to make sure it's closed when cold and wide open when warm, and check the AAP to make sure it's not leaking.

[Petros]

Welcome to the forum,

sounds like a bad vacuum leak. it makes it lean and difficult to start, it will die at low rpm, and likely be weak at all rpms. check all your vac lines for connections at both ends, cracks or cuts in the hoses, and they are routed properly based on the vac diagram for your car year and model (it is in the FSM on this site).

Also check that the manifold bolts are tight, and the vac line from the lower part of the carb to the airfilter valve body is connected and in good condition.

do not start messing with the carb until you eliminate all other things that can cause a run lean condition. Always diagnose the problem BEFORE you try and fix it, or you can make it worse, and cause more problems for yourself. at best you are wasting time finding and fixing the cause.

i once bought a Tercel4wd that ran like crap, seller said it needed a carb rebuild. I got it home and found 9 (yes, nine) vacuum leaks and misrouted hoses. after a carb adjustment it ran perfectly after that. I never did rebuild the carb, sold it after I clean it up and fixed some other issues, at a small profit. so do not assume you need to "fix" the carb,

[dlb]

petros makes a good point. a bad vac leak could cause your symptoms. in addition to the vac hoses and manifold bolts, make sure the 12 mm carb mounting nuts are snug. you can reach all of them with an extension but be careful not to overtighten them. i have had a few of the studs snap off.

if you don't find anything there, you can also let the engine idle and then spray carb cleaner around different areas of the carb and intake manifold. if you hear the RPMs rise when you spray a particular spot, there is a vacuum leak there.

[Bad-4-Toyota]

Hi Again!
I don't think it's a vacume leak, because A it runs very well and revs up nicely and B I checked all the vacume lines. It seems more like a fuel issue. Under 2000 it sort a runs out of fuel. (Thats where I set the idle) The carb was gummed up before, and was cleaned. But still has some issues like I said. Do you think a carb cleaner would work? Or is there something else I could use/do to get the fuel flowing through better? Thanks a Ton!

[irowiki]

Does it flat out just die below 2000 RPM? I'm not so sure it is a fuel issue. Maybe your throttle positioner is adjusted too far out. Did you verify everything is connected to the correct port? This can take a while and there's several nice diagrams in the repair guides section of these forums.

It can still run well, rev nicely and die at low RPM's due to a vacuum leak because the engine is running too lean past that point.

It is not just about the vacuum lines. You might have leaky diaphragms. When testing a diaphragm it should be able to hold air when you put your tongue over the end of the line after you suck in. Get a decent length of vacuum line and test the following:

1. Vacuum advance located on the distributor. Count the ports, it'll either have two, or three. If it has three, test the upper (single) port by itself. Hold your finger over one of the lower ports while you test the other port.
2. Choke breaker (rear right of carb as you are looking at it), two ports to check
3. choke opener (front right of carb)
4. Throttle positioner (front of carb)
5. EGR valve
6. Maybe the EGR modulator, not sure about that one

Is the rubber boot over the acceleration pump intact? Are all check valves, VTVs (vacuum transmitting valves), and jets intact? IS the TVSV (on the coolant outlet with 6 hoses connected to it) cracked?

There is a rather large line from the base of the carb to your air filter, is that in place?

Is your PCV valve intact? Is that line to the base of the carb intact?

You might make sure the intake manifold bolts are properly tightened, perhaps check the carb bolts too.

You say the carb was cleaned, how so?

Have the spark plugs, plug wires, distributor cap, and rotor been checked?

There are other things that could cause poor idle, try the troubleshooting section of the Engine MEchanical section of the FSM available for download on this site.

[Bad-4-Toyota]

Hi Again!
It seems like that the carb is working now. It stops and starts OK. And revs well. But it stops at 1500 now. It just chugs a little while then stops. The pump rubber it ripped up, but still works a bit. I cleaned the carb by soaking it in diesel for three days, then taking it apart and brushing it out. Then I brushed it out with gas, and finished by blowing it out with air. This morning I took the top off the carb, and fished some wire into the little inlet for the left and right injector. Some junk came out and now it runs. Maybe there's something else I could do to clean it better? All the lines/valves/etc are good. And I don't think there are vacume leaks. The other thing is that this carb came off of a motor that was sitting upside down. And a lot of oil got into it. The original carb was having all sorts of problems. So I replaced it this this one. Does anyone know of a real good carb cleaner maybe? Or is there something else I'm missing?

[irowiki]

Still sounds like a vacuum leak. Every one of my cars has refused to idle any lower than 1.5-2.5k rpm and after digging I find some evidence of a leak.

Not saying it isn't doing it but you have to be through!

[dlb]

what do you mean "it stops at 1500 now"? do you mean it is now idling at 1500 when warmed up?

there are so many potential spots for vac leaks on these carbs that i don't think you should rule them out without actually checking every possibility. it only takes a few minutes. many folks here have been surprised to find loose intake manifold bolts or even a cracked manifold. no matter how many times you rebuild a carb, it can't make up for a those kinds of leaks.

i actually just edited the section of the FAQ that pertains to this sort of stuff so take a look there. it's FAQ #6.

https://tercel4wd.com/forums/viewtopic.php?f=2&t=7442