No spark on 83 tercel

[80sYodafan]

Hi there have been using this forum for a while but recently joined because it seems I’m at the end of my rope. Im a big fan of 80s Toyota and have had most models of these cars offered in the states. I acquired the Tercel 4wd wagon a couple years ago at what I thought was a fair price 1200$(has 140k). However driving it home it died with classic coil symptoms(randomly died, restarts after a short time getting worse and worse) I replaced the coil which is not in the easiest to access location and the car ran pretty alright for a couple of weeks or about 200mi then started having similar symptoms only when started would die within a couple minutes. Using the valuable information contained in these pages I found the igniter to be bad so replaced it. It ran well for exactly one day and then similar problem. I figured some contact was loose and replaced or improved grounds(looking a little rusty) and then proceeded to test continuity and found while shaking wires the ignition switch was bad. I replaced that and had no noticeable change. I then went through and checked everything again following fsm procedures. Distributor all checked out. I saw someone suggested replacing the entire distributor so I got a used one ran bench tests and…no dice. I had a friend come over and help me so I could recheck the distributor isn’t sparking while motor is cranking and that rotor is spinning while cranking. No spark and rotor turning. I removed the fender to check if a rodent had chewed wires from fuse box to dash…nope. Everything under the dash looks good minus a hack radio install which instead of using one power looks to be supplied from a solid black wire(if I remember). Another interesting thing is the PO connected the electric radiator fan to the headlights so it turns on with headlights. I checked the wiring diagram and required the fan per spec replacing the temperature switch in the process which tested bad and was probably the impetus for the brilliant wiring. I’ve checked all fuses and the alternator fuse was missing but still charging. The problem is the car won’t spark and following the wiring it appears there are to proto computers hooked up to the distributor. Can anyone tell me if there is a no run condition involving one of these computers? The main distributor wire has power in vehicle on position. Could it possibly be the fuse block? Basically any ideas why a relatively simple car won’t run. I’ve converted a pickup to Efi and a van to carburetor and understand quite a bit about what’s necessary to run. I just can’t see why when everything seems to check out I can’t get spark( has power, rotor spins, body grounded) I’ve spent a ridiculous amount of time trying to figure it out!

[Paul]

I wonder if you have 2 bad distributors? Can you connect a meter between the power (B-Y) lead and distributor case ground to verify 12v during cranking? Are you trying a different cap and rotor too? Maybe the high voltage is getting stopped there. In the repair guides section, Nordical25 has a distributor rebuild posted that might offer clues to something that was overlooked. The emissions computer looks at the tach signal to put carb mixture control in "closed loop", but I'm not aware of any system that kills ignition.

[80sYodafan]

I’m almost positive that the blk/yellow has power when key is on but will recheck. I didn’t think to try while cranking but will try tomorrow when there is light and it’s a bit warmer. Thanks so much that be all I needed! I can’t believe I didn’t think of that considering all the stupid things I did think of. I’m fairly confident its not a bad distributor (either one). They both have been tested via Fsm and the bearings are good. Based on my experience the distributors are pretty hard to kill. Do you know if the other black wire running to distributor should have power at any point? Thanks for the insight. I have a new cap and rotor and have rotated through all three in combination with no luck

[dlb]

I've never heard of the ECM causing a no spark or any other kind of no run situation with these cars so I don't think that's your issue.

I'm not clear on whether you actually installed the second distributor, did you do that or did you just bench test it? I honestly find a lot of the FSM test procedures to not work -- most of the devices I have tested fail the test but in application work fine, with my cars running well and getting good fuel economy. So I wouldn't trust all of those results, personally.

I agree with Paul that two bad distributors is very possible. I'd also add that between the shoddy wiring of the stereo and rad fan, and the alternator working despite not having a fuse, I wouldn't trust anything in that car. It sounds like a previous owner really messed around with some things so I would sort out those known problems first since you know they are suspect, and then check the distributor wiring in the car to see if they messed with that too. Maybe they spliced something into it poorly.

[80sYodafan]

Man all this great help! I did try both alternators and neither seemed to change anything. The reason I ask about ecm and emissions control is that my understanding is that one or the other has the ability to slightly advance or retard timing based on inputs from vacuum switches and oxygen sensor.
Another idea is I’ve heard of cracked fuse blocks under the hood doing funny things when various loads are switched on and off. I’d prefer to diagnose before throwing a ton of parts at it. There is a cut wire under the dash that is solid black which is the same color as the other wire coming from the distributor. The wiring isn’t that bad it doesn’t seem. Whoever did the fan thing just melted the insulation off the headlight wire and twisted a splice. The main harness looks factory and unmolested.
I really appreciate all the help! I’ll hopefully get some time to mess with it tomorrow and do some more tests. If anyone knows exactly what influence the “computers” have over spark I’d love to know. Also is it possible to set the distributor on a bench provide 12v and spin the shaft by hand to get spark?

[SirFoxx]

Man all this great help! I did try both alternators and neither seemed to change anything. The reason I ask about ecm and emissions control is that my understanding is that one or the other has the ability to slightly advance or retard timing based on inputs from vacuum switches and oxygen sensor.
Another idea is I’ve heard of cracked fuse blocks under the hood doing funny things when various loads are switched on and off. I’d prefer to diagnose before throwing a ton of parts at it. There is a cut wire under the dash that is solid black which is the same color as the other wire coming from the distributor. The wiring isn’t that bad it doesn’t seem. Whoever did the fan thing just melted the insulation off the headlight wire and twisted a splice. The main harness looks factory and unmolested.
I really appreciate all the help! I’ll hopefully get some time to mess with it tomorrow and do some more tests. If anyone knows exactly what influence the “computers” have over spark I’d love to know. Also is it possible to set the distributor on a bench provide 12v and spin the shaft by hand to get spark?

the smog ecm does not interact with the distributor whatsoever on these cars. i think you are looking too deep into the ecm based on your history with FI on other toyotas. if youre losing spark you have a bad dizzy, or a shitty 12v connection.

yes, you can hook up 12v and ground to the dizzy and spin it to test for spark.

[Mark]

My automatic Tercel wagon has the primitive computer. It doesn't interact with the distributor. It just takes an input from the oxygen sensor and inputs from 2 vacuum switches (to tell if it's at idle or cruising speed). It then opens and closes a small air bleed valve on the carb every second or so to lean out the mix. This makes the fuel-air mix to go lean-rich-lean-rich, etc..., but the average of the swings should be about ideal. Maybe this is a stupid question, but are you sure that there's no spark or are you guessing? If you pull a spark plug with the wire attached and start the car, there won't be a spark unless the body of the plug (like the threads) is grounded to (touching) the engine. By the way, you said you replaced the coil which was in "a hard to access location". Does your distributor have an external coil? The 1st gen non-electronic distributors has an external coil, but our North American 2nd gens should have the electronic distributors with the coil in the distributor.

[Paul]

The black wire is tach output. After the ECM, it goes to the AC amplifier to disconnect the compressor if RPM is too low. Probably just a pulsed output signal on that wire.
The high altitude compensator (HAC) will advance timing by applying vacuum to the sub-diaphragm on the distributor, but no computer action here.
Do you have one of these inline spark checkers?

20241122_095624.jpg

You could also temporarily attach a small test light to the B-Y distributor power to verify it's solid.

[Mark]

If you have the electronic distributor, I wonder if the noise filter (capacitor) mounted to the side could be somewhat broken down and intermittently grounding the power supply. All it does is reduce the whining noise in the stereo from the electronic interference from the coil. I'd try disconnecting it (unbolting it from the side of the distributor) so it doesn't contact anything. It's a longshot, but an easy check.

noise filter.jpg

Here's a photo I stole off this site:

noise filter 2.jpg

[80sYodafan]

To be honest I wasn’t expecting so much help so quickly! Amazing the knowledge out there and people willing to share it! I guess that what it means to be a community. I haven’t had time to make any progress got called to go work.
@sirfoxx thanks for clarification on the output of ecm. I think you’re right and I’m overthinking this but I’ve never had so much trouble diagnosing something so simple(relatively) also cool to know I can bench test the dizzy without having it installed so can do quicker status testing.
@mark I’m sure it has no spark(used timing light and screwdriver trick). I checked ground from dizzy body to head and dizzy body to body. I used multi meter to check voltage at bk/y. I definitely have the integrated distributor which is not my favorite hard to get cap off while distributor installed and annoying. Thanks for more enlightenment on function of ecm I figured it was like the other cars from this era and not absolutely necessary for basic functionality.
@paul Now I know what the other black wire does! I do not have that test light anymore probably worth the couple bucks to get one again. Timing light should be equal though yes?
So I think thanks to all the help it is just me way over thinking it. seems the dizzy is basically a one wire setup that should fire through mechanical rotation. Toyota simplicity! So bad dizzy, or bad wiring as mentioned. I’ll bench test the distributor that isn’t in the car first and if I get spark install it and put the meter on it in series to see if voltage drops on crank. Thanks for setting me straight! I’ll definitely be back to let everyone know how it goes as I know it really sucks when everyone helps out and original poster doesn’t get back to let everyone know what worked or didn’t.
Just saw the noise filter thing. I saw it in the diagram and talked to my electrical engineer dad and he said it could do exactly what you said! I just didn’t know how to isolate it now I do! Amazing!

[80sYodafan]

So today I finally got a little time to work with the Tercel. I decided for redundancy sake to stop by the auto parts store and buy a new distributor cap because it was one thing that I hadn’t changed and while there it was just a few bucks for a new rotor too so what the heck! I got home and took the distributor that was out of the car and hooked up power to blk/y and grounded the battery I took and one of the old spark plug wires I replaced and an old plug and turning the shaft by hand got spark! While I changed out the distributor assembly I threw the battery on the charger(it’s been sitting a couple months) just to be sure I got power. I also dug around and verified the stereo install. It wasn’t totally bad and the dangling wires were all speaker wires and the black turned out to be the ground from the back of the stereo. None of the original harness had been cut! One less thing to worry about. I rechecked all the grounds and positive wire to distributor and plugged everything back in that was unplugged. When I couldn’t wait anymore i hooked up the battery. Since it had been sitting I dumped about a teaspoon of gasoline in the carb and went to crank it over. It fired right up! It still won’t idle exactly right(probably timing off).
I can’t believe my lack of attention to detail the distributor caps or rotors must have been cracked or something because on cursory examination they looked good plenty of brass left and springs in contacts still moved. I went through and changed plug wires, igniter, coil(once was actually bad?) magnetic pickup and failed to do the cheapest easiest and most basic thing because they passed visual inspection. I feel like a fool! It seems I likely had two bad distributor caps! Odds were against it so I ruled it out. I tore through so much of my car looking for a complicated solution when the simple one was right in front of me. Well K.I.S.S: really rings true.
Without the help of people on this board I would still be ripping apart my car looking for gremlins that don’t exist. I’m truly and deeply grateful for the help! Hopefully some day I can be that guy. Chances are I have another working distributor once I buy another cap and rotor(I have to test it still) so anybody in the area could borrow it to potentially resolve their issues.

[dlb]

Glad to hear you finally got it sorted out. I'm sure we've all done similar things a number of times so you're in good company here.

[80sYodafan]

So I got the distributor in and have spark(confirmed by timing light) I dumped gas in the carb bowl and got the car to start but would only stay running with foot to floor. Figured timing had been lost or buggered at some point so I pulled distributor and timing cover set to tdc(all marks lined up) re installed distributor per fsm and now even with wot won’t start. Still have spark, pulled all plugs and all are sooty so rich. Carb has fuel in sight glass and smells like gas while cranking. Every once in a while gets a little explosion from tailpipe. I didn’t pull crank pulley just used timing marks to confirm tdc and marks on the cam sprocket. Am I missing something here? The carb is a rebuilt Toyota unit from national carburetor. I installed the distributor with cap open and with marks at tdc rotor was just past the #1 post. Even with the distributor one tooth off it should run. I wanted to check compression but seems the adapter for my compression tester is missing. Plugs don’t have any oil on electrodes. I feel like I’m drowning in this thing.

[dlb]

You might be at TDC but on the exhaust stroke. Plug the #1 spark hole with your thumb while you crank the engine clockwise using a ratchet on the crank pulley bolt. When you feel pressure build up under your thumb as the piston reaches TDC, you know you are on the combustion stroke. NOW REMOVE THE RATCHET SO YOU DON'T FORGET IT AND ANNIHILATE YOUR RADIATOR WHEN YOU GO TO START THE ENGINE. Then make sure the distributor rotor is pointing Northwest (or 10:30, however you prefer to say it).

[80sYodafan]

I’ll try it that way but my understanding is that if both can and crank marks are at tdc it should be compression stroke ?i had to make almost 2 complete revolutions for both to line up I wanted to check that t-belt was installed properly. It is…I feel like this car will be the death of me. I also have a 89 corolla all-trac that’s getting bad fuel economy and want to move on to that project but this guy has had me pulling out my hair for months.