Troubles after carburetor rebuild

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Q23456789
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Re: Troubles after carburetor rebuild

Post by Q23456789 »

So I have another update. The car seems to be idling relatively smooth right now, but it still stutters a bit. It still randomly diesels and backfires out of the intake though. I set the base timing at 10 degrees advanced. I did notice that once I plugged the vacuum lines back in, it didn't advance the timing at all at idle. Is it supposed to adjust timing at idle? The cap and rotor look to be in pretty rough shape, so I am going to do that along with plugs and wires. That might improve the slight roughness, but I doubt it will help much with the dieseling. Something weird though, the choke doesn't ever seem to shut. I am pretty sure that it did before I took the carb off the last time. Is there a spring that's supposed to pull it closed? The two vacuum diaphragms only seem to open it. The two piece set up on the back side of the carb that the choke linkage goes to is all in the right place with the one spring in the middle, but the choke never seems to shut? I am going to look up pictures to make sure it's all dead on right, but I am pretty sure I have it set up the same as I did before. I wonder if the choke not shutting has anything to do with the intake backfire? Weird little things. Thanks again for all of your guys help! I will be sure to post when it all gets figured out.
oldfaithful
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Re: Troubles after carburetor rebuild

Post by oldfaithful »

If you have your timing set at 10 degrees you can plug the vaccum lines, you don't need them and it will work away better, use premium gas not low octane fuel and that should eliminate your diesling problem as well.
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BaileySims
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Re: Troubles after carburetor rebuild

Post by BaileySims »

I have an extra vacuum advance piece for the dizzy if you need it. It's a little banged up but I know it works for sure.
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xirdneh
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Re: Troubles after carburetor rebuild

Post by xirdneh »

on front top of carb there is linkage that the vacuumm moves to lock choke open when engine reaches certain temperature. if the diaphram is bad it will not work or there is no vacuume getting to the diaphram, could be hole in vac line or TVSV is not functioning right. there are two diaphram housings on front driverside of carb and its the small one.
Love those Tercell 4x4 wagons but they sure suffer from road noise.
Q23456789
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Re: Troubles after carburetor rebuild

Post by Q23456789 »

The choke opens no problem, but it never shuts. Unless I shut it by hand. Even when I do that, when I pump the gas to start it, the choke springs open and stays there.

I did the tune up on it, and it helped it out a lot. There was some pretty worn parts. I found a little vacuum leak at one of the lines and fixed it, and I think I found a vacuum leak at the intake manifold to cylinder head gasket. That would explain a lot. So I am going to go and replace that, hopefully that is the issue. Drove the car around a bit, and it drives great! It just doesn't like to idle. I am sure that it's just a vacuum leak. It's tough to find the leak with carb cleaner, because the idle is so random. I will probably try and smoke test it before I pull the intake off to make sure.
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Petros
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Re: Troubles after carburetor rebuild

Post by Petros »

often the heat cycling of the intake/exhaust manifold causes the mounting bolts to back off. Usually all you need to do is tighten the intake/exhaust mounting bolts and it seals up just fine. No need to remove and replace the gasket unless it is blown out or damaged. Usually the metal gasket holds up just fine and you just need to tight down the bolts.

try and get to all of them, there a few hard to reach under the heat shield, and from the underside of the manifold. sometimes a mirror helps to locate them from underneath, a box end wrench helps to reach them.

good luck
'87 Tercel 4wd SR5 (current engine swap project)
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Re: Troubles after carburetor rebuild

Post by xirdneh »

Did you take the black plastic choke cover off, the coil spring in there can pop out of place. Only seen that once. I replace the rivets with screws. When drilling out the rivets it goes better if you punch the pin out of the rivet. Use a rivet stem to knock it out.
Love those Tercell 4x4 wagons but they sure suffer from road noise.
Q23456789
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Re: Troubles after carburetor rebuild

Post by Q23456789 »

I did take that cover off, is there some procedure to clock that spring on the housing when you put it on? I kind of just put it on how it looked like it should fit, I didn't see anything in the FSM about clocking it.

I will try and just tighten down the intake bolts and see if that helps.

Thanks again for the help, it is much appreciated.
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Re: Troubles after carburetor rebuild

Post by xirdneh »

The one I had problem with needed to have the contact point with the spring adjusted cause it would pop out of position. I bent it so it fit better. Been a while so I do not recall details.
Love those Tercell 4x4 wagons but they sure suffer from road noise.
Q23456789
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Re: Troubles after carburetor rebuild

Post by Q23456789 »

So I am pretty sure I found the problem(s)! Intake bolts all ended up being tight, so I determined that I should do the gasket. In the process of removing the bolts for the intake and exhaust, I pull a bolt out and I hear something metal fall. The bolt still had a washer on it, so I wondered what dropped. When I looked I found a chunk of the intake manifold laying on the water pump. The manifold had cracked around the number one runner, at the very front bolt. The break went clear into the runner, and not just the edge where the bolt hole is. So after a few nasty words, I start pulling the intake completely out and notice that the exhaust manifold has similar cracks toward the inside two mounting tabs, though not nearly as bad. So I need to replace both of them.

So I am now wondering if the intake manifold would work off of a FWD Tercel? I am sure the exhaust won't, but will the exhaust manifold off of a RWD 4ac work? Just trying to give myself more options for my next junkyard trip, in case I am not lucky enough to find a 4wd Tercel at the junk yard.

Thanks again everyone.
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Petros
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Re: Troubles after carburetor rebuild

Post by Petros »

I guess you found the source of the vac leak. when you put in a replacment, make sure the bracket that goes under the intake/exhaust manifold is in place and it is bolted to the side of the block. It supports the intake/exhaust manifold from underneath. I find that bracket a neusance and am tempted to leave it off every time I have to pull the head, but I suspect that is the reason it must be present.

If you need both intake and exhaust you might just get them both as an assembly. Not sure if the RWD 4ac manifold would work, though likely it is identical becasue the early heads of 3a and 4a are almost identical. all of the '83-86 second gen Tercels intake/exhaust assemblies should be interchangeable, not just the 4wd.

If you can not find one locally, there might be other forum members with extras they can sell you.

good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
Q23456789
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My tercel:: 1984 4wd Tercel, stock

Re: Troubles after carburetor rebuild

Post by Q23456789 »

I found a set of manifolds off of a FWD Tercel, did not realise they were longitudinal layout too. I got the manifolds on late last night and everything went on fine, the old support bracket was there and I reinstalled it. I will reinstall the carburetor and do the valve cover gasket today. Sense I have the carb off, I will try and figure out what's up with the choke. Hopefully this fixes my problems.
Q23456789
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Re: Troubles after carburetor rebuild

Post by Q23456789 »

Well, I got the intake all changed and everything put back together and it is STILL idling rough. It's acting like there's still a vacuum leak, but I can not seem to find one anywhere. What's kind of weird is it seems to be over fueling pretty hard. After running it for a while and shutting it off, I can see liquid fuel in the bottom of the intake through the throttle blades. Also, if I purposefully open up a vacuum line and give it a vacuum leak it seems to smooth out. I have reset the idle mixture screw to the 3 and 1/4 turns out, and tried adjusting back and forth a few rotations but it seems to have no effect on how it's idling. Once you take it up in the RPMs, it smooths out really nicely and sounds very healthy. It just doesn't want to idle. Valve timing and ignition timing are both set, and I have plugged the three hoses off the vacuum advance because the unit isn't working. I have checked all the intake and exhaust bolts to be sure they are tight. The only real lead that I have is it seems to be adding way too much fuel.
jimcrazy
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Re: Troubles after carburetor rebuild

Post by jimcrazy »

sounds like your slow jet may be still half pluged up,,i had to clean mine after it would not idle good,,did it with the carb still on and used a dob of crazy glue on the screw tip to lift it out of the hole
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Q23456789
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My tercel:: 1984 4wd Tercel, stock

Re: Troubles after carburetor rebuild

Post by Q23456789 »

I will check that slow jet out.

One more thing I forgot to add is that when you give it some throttle, usually it doesn't drop all the way back down to idle. Sometimes it will stick around 2000 rpms, sometimes around 1200, and anywhere in between. It also kind of bounces around when it's dropping to any of those rpms. It's not the throttle sticking, you can watch it drop all the way back down and can even push it all the way down when you give it gas.

It also decided to change it's mind and stop over fueling. It isn't flooding out now, and when you give it a vacuum leak, the idle drops and it runs worse. The inconsistency is probably the most annoying part.

Thanks for the input. I will be sure to check out the slow jet.
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