Last of my woes

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AlexArrow
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My tercel:: 1986 Toyota Tercel SR5 Wagon 4WD
Location: Moose Jaw, Saskatchewan
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Last of my woes

Post by AlexArrow »

Well, I got the majority of the problems fixed, but a few still left. Generally, it is running fine, but would still like to sort out a few of the problems.

Probably the biggest problem that was causing most of the trouble was the vacuum-operated 'choke opener' (not to be confused with the breaker). Turns out, it opened the choke immediately. I had to disconnect it and plug the line for the choke to stay closed long enough.

Dunno, but that might have something to do with the next problem; seems the regular and fast idle are not operated/set independently. Understandable?

Next is a little odd. Seems the electrical system is staying on for a second or few after turning off the key. This also causes the engine to run for a sec or few.

Speaking of the engine, it isn't all smooth yet. It is still a little, uh, 'lumpy'/'surgey'/'bumpy'. It is most noticeable when cool, accelerating or cruising(just enough throttle to keep it at speed). Worse at accelerating when cool - hesitates and repeats. Pretty sure it is from the engine, since there is less when warm and idling/light load and when I am moving, but put in the clutch. Can also bee seen on the tach's needle movement.

Is all that understandable?
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NWMO
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Re: Last of my woes

Post by NWMO »

seems the regular and fast idle are not operated/set independently. Understandable?
These are set/adjusted independently as covered in the FSM.

For rough running or surges, etc. I would consider carb service or rebuild.

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: Last of my woes

Post by Petros »

you describe cold starting issues that are normal to carburetor operation. we have been spoiled by modern fuel injection that automatically adjusts the fuel air ratio for temp and driving conditions.

when you are starting from cold, you have to stomp the pedal to the floor 2 or 3 times, this should set the choke closed, and sets up the fast idle cam on the linkage. as it warms the idle speed should step down each time you step on the pedal (if you just let it warm up from cold without touching the throttle, the idle speed will keep going up as it warms). Once fully warm the throttle linkage should be all the way down on the main idle speed stop that has a separate adjustment.

when it is cold and running, if you have a flat spot and it hesitates and stumbles when you try to drive off, that is an indication the choke is not working properly (the mix is too lean), or there might be a vacuum leak from somewhere making the mixture too lean. And/or, the Auxiliary Acceleration Pump (AAP) is not working, it adds extra fuel when you stomp on the pedal when it is cold to prevent hesitation, once warmed up this is cut out of the system, so it is only an issue for cold driving on first start up.

Either way you have to check that all the vac lines are routed properly, connected where they should be, and there are no cracks or leaks in any of the lines. once that is done there are several adjustments you have to make, each in turn, to the cold start and linkage, so it will run well, and you can narrow down all the issues. It is not that complicated once you have run through the checks and adjustments, you just take them one at a time as indicated in the Service manual. in the Service manual (FSM), that you can down load for free from elsewhere on this forum, there is a chapter that walks you though each of the systems tests (simple, usually no tools required), and adjustments to the linkage. Do it in order and it should help you locate any leaks, or out of adjustment linkages. than it should run fairly well. if not, than you will need to narrow down what might be not working correctly. but you can not diagnose anything until you know there is no vac leak, all the vac lines are routed properly, and the linkages are all adjusted correctly. that has to be done before you can find anything else because it will mask what ever else is going on.

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)
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dlb
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My tercel:: '87 sr5, '83 dlx parts car
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Re: Last of my woes

Post by dlb »

AlexArrow wrote: Sat Dec 04, 2021 3:24 pm Well, I got the majority of the problems fixed, but a few still left. Generally, it is running fine, but would still like to sort out a few of the problems.

Probably the biggest problem that was causing most of the trouble was the vacuum-operated 'choke opener' (not to be confused with the breaker). Turns out, it opened the choke immediately. I had to disconnect it and plug the line for the choke to stay closed long enough.

Dunno, but that might have something to do with the next problem; seems the regular and fast idle are not operated/set independently. Understandable?

Next is a little odd. Seems the electrical system is staying on for a second or few after turning off the key. This also causes the engine to run for a sec or few.

Speaking of the engine, it isn't all smooth yet. It is still a little, uh, 'lumpy'/'surgey'/'bumpy'. It is most noticeable when cool, accelerating or cruising(just enough throttle to keep it at speed). Worse at accelerating when cool - hesitates and repeats. Pretty sure it is from the engine, since there is less when warm and idling/light load and when I am moving, but put in the clutch. Can also bee seen on the tach's needle movement.

Is all that understandable?
If the choke opener is opening at the wrong time, it must be connected to the wrong vacuum source. Follow the hose and blow through one end while covering the other end with your finger. That way you can make sure that the hose you are playing with is the right one.

The engine running on after turning the key off is called dieseling and can be caused by a few things, usually it's either from running rich or the timing is too far advanced. Use a timing gun to confirm that the timing is correct -- with the vacuum advance disconnected and plugged, it should be at 5-10 degrees BTDC. For running rich, check the AAP like petros mentioned, and check the float level to make sure the level in the fuel bowl is between the two points of the sight glass (make sure to be parked on level ground when doing this).

The rough running you describe could be due to vacuum issues (make sure all the hoses are going where they are supposed to) but it could be due to incorrect timing. Another timing thing to check is that the mechanical advance is working properly: with the distributor cap off, twist the distributor rotor counter clockwise. It should give a few mm and then snap back to its original position. If it doesn't, you can fix it or replace the distributor.
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AlexArrow
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Posts: 18
Joined: Fri Nov 06, 2020 5:48 pm
My tercel:: 1986 Toyota Tercel SR5 Wagon 4WD
Location: Moose Jaw, Saskatchewan
Contact:

Re: Last of my woes

Post by AlexArrow »

Thanks!

I just kept working on it until I got things sorted out.
When I got the cars, they sat for years with untreated gas left in them, so the carb needed cleaning.

I actually figured out the 'dieseling' part; since the temp. sensor wasn't turning on the fan, I wired it to a switch and found if I left it on when turning off the car, it caused a short or something, causing dieseling thing to happen. So I just turn the fan off first.
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