Ignition problem 1982 4G52

[KGR1989]

Just tried a jump wire directly from the battery to the ignition switch wire while someone was starting the car and still nothing. I've exhausted just about all things I can think of on my own lol

[KGR1989]

Oh and to answer Star's question my coil is just an Accel coil. Doesn't say anything about ballast requirements and neither does the old coil which was a MegaFire one that looked like it was from the 90's.

[StarquestMan]

Ok im guessing that both coils should be internal resistor type. the reason you see about 12v on the coil- is that even though that is the ground side of the coil it isn't directly connected to ground. instead it gets its ground through the ICM which grounds to the distributor. this is good because it would indicate that power is flowing through the coil and that the winding's are good (well 1 of the 2 windings). I have a bit of an experiment for you to try that may tell us if the new ICM and or pickup coil are bad. try hooking up the coil with the power wires (black with white stripe) connected but leave both brown wires disconnected since the tach is extra and im not 100% sure about the little brown wire. then with the key in the on position check that there is power on the black and white wires, take a jumper wire and connect one end to coil ground hold the other (make sure it is insulated or that you have a glove so you don't get shocked. take tap the end of the jumper wire to ground and watch for spark. if you get spark then that means that the coil is good and that the wiring is not the problem. the little brown wire having .2v on it is probably just stray voltage that is throwing the meter off. Looking at the size of it too i would guess it is a low current signal going to the engine computer or something, it doesn't look heavy enough to power the ignition system like the black with white stripe wire.

[StarquestMan]

Also do you have a little test light? the reason i ask is that it may give a better reading for some of these tests since it draws a bit of current that can tell you if the ignition switch is flaky

[StarquestMan]

Just looked at my 86' conquest and it doesn't use a ballast resistor either, then i noticed that when the previous owner (the original owner) put in an aftermarket MSD coil he wired it in backwards! but the car ran just fine

[Giovanni89]

Time to start simple and check one component at a time. Disconnect everything on the coil. Run a plug wire from the coil tower to a plug with a spark checker. Run a jumper from battery to the + side of the coil. Run a jumper from the - side of coil. When you ground the - wire and then pull it away, you should get a spark.

[KGR1989]

Alright so I’m back after the holidays. Doing some testing right now actually. I’ve got another car hooked up with jumper cables since my battery is dead. I’ve hooked up everything as Giovanni said, I just don’t have a spark plug wire tester. I left the constant power hooked up and ran a jumper wire from the battery ground to the negative side and I got sparks on the moment it contacted, but no sparks coming from the wire end that is beside a ground.

I have the cap and rotor taken off and I’m using a multimeter and I’m getting 14V on both sides of my igniter (ICM). I’ve spun it over and verified that the distributor is actually turning also. I’m about to pull the igniter off and verify again the connections on it. I have a test light also, but I’ve just been using a multimeter instead.

[KGR1989]

14V going through the igniter as well and the pickup coil has 14V going to it also. I switched to the old pickup just to try and same results. I am stumped lol.

[KGR1989]

Well, this little black switch mounted on the same bracket as the ignition coil with a vacuum line to it is getting hot...not sure what exactly it does. Electrical harness with two wires on one side and a vacuum line on the other? 4D6EDC81-E6D4-422C-BA33-A71F9D56FD50.jpg

[KGR1989]

ANNNND I UNPLUGGED IT AND IT STARTS what is this LOL

[geezer101]

Well ladies and gentlemen, that... is a new one. I personally have no freakin' idea why the ignition system would need a vacuum triggered cut off/activation switch but that's what it looks like. The fact that it is getting hot means to me that it is causing a dead short across the coil (there must be a load being put on it for it to generate heat...) Where does the other end of the vacuum line go to? It would be a little tricky to test it as you'd need to be cranking the engine while applying a vacuum to the... 'thingy' to get it to break the circuit and allow the engine to fire.

[KGR1989]

If I remember correctly it went to the carb, I'd check but it's raining pretty hard today. It's been running just fine since I messed with it though. It might be a vacuum advance for the timing? I don't honestly know lol. Very strange and lucky how I found it though. Put the little truck to work yesterday and hauled a lot of logs that I cut and split. Not a single problem out of it either. Starts right up just like before. Now when I shut the truck off it seems a little odd. Turn the key off and it dies down like normal and then right before it's entirely off it sputters and then shuts off. Can't remember it doing that before, but I don't really think it's harming anything by doing that so I'll just leave it be and not fix what's already working. I'm just glad to have it back working again.

[KGR1989]

Here’s a photo of it loaded down. Back bumper was squatted down close to the ground!1260EA77-F756-4003-B33C-A94F29790337.jpg

[geezer101]

OK another theory from Geezer - the vacuum switch disables the ignition coil when there is zero vacuum available so it might be (for some bizarre reason...) there to kill the coil to prevent the run on issue after the ignition is killed (still don't know why it would even need it). The ignition advance servo is on the distributor so that is a different control peripheral. If it's running on afterwards, check your ignition timing and check your plugs to see if it's running rich. The run-on is not good for the engine. Gen 1's came in 2 load ratings - 500kgs and 1000kgs. The 500kg rated trucks are easy enough to identify - just look at the tail/drive shaft. If it looks like the diameter of the shaft is on the thin side, it'll be a 500kg truck. AFAIK the differences between the 2 rated load capacities are the drive shaft, the front stabiliser bar and the upper control arm pivots. Not sure of the spring ratings but it would be logical that there would be an uprated spring on the 1000kg trucks.

[StarquestMan]

Hmm this thread is interesting! Similarly to what geezer mentioned that vacuum switch could be for if someone turns the key on but doesn't start the truck and the rotor happens to be sitting on one of the firing positions it could maybe turn the coil on for too long thus burning something out? I believe this sort of thing happens with points ignition and now im thinking this may be possible with early style electronic ignition. maybe thats why they went to the later style ICM around 84' or so. Now i'm super curios what thats for and how its wired lol. maybe my generic chilton manual covers this setup, ill have to dig it out.

[KGR1989]

Well I drove it to work tonight and on the interstate for the first time since it’s been fixed and it’s fine until I get into 4th gear and then it just starts popping. If I back out of the throttle a little it’s fine, or if I drop to 3rd gear it’s fine.

One thing I noticed when I put the new wires on was that they’re slightly shorter than the ones I took off. About 3 inches each wire. Had to run them over the valve cover instead of in it’s keepers. Would this cause an issue like this? My mind is telling me no because if it was that it’d be constant not only at a certain load on the engine. I’m thinking that little vacuum thingy isn’t working properly.

Thoughts?

[KGR1989]

I should also mention that it’s 4th gear when I’m going about 65 mph or so.

[geezer101]

If it's breaking down under load like that, I'd suspect the ignition coil is sketchy. If you haven't swapped it and it's more than 10 years old, I'd think about replacing it. A tired coil will have trouble keeping up with higher rpm's and start misfiring.

[KGR1989]

Lol everything on the ignition system except the actual distributor and that vacuum thing is brand new. I’m going to replace it and see if it helps. When I drove it home last night it acted fine until it warmed up a bit and right at 70mph it starts popping if you’re more than about 40% throttle. After 60mph it feels a bit sluggish but doesn’t pop or anything until 70.

[claych]

^^^
[quote=geezer] If it's breaking down under load like that, I'd suspect the ignition coil is sketchy. If you haven't swapped it and it's more than 10 years old, I'd think about replacing it. A tired coil will have trouble keeping up with higher rpm's and start misfiring.[quote/].

[KGR1989]

Ignition coil is brand new. It's an Accel one from Oreilly's. I mean I guess there's a chance it could be bad though. I've got the old one that was on it and wasn't bad. I'll swap it out and see if I've got the same problem or not.

[geezer101]

Next question - you got the ballast resistor in place? Ignition systems can do weird stuff if the incorrect impedance is placed on them and there is a possibility that the distributor isn't liking the Accel coil. If it behaves itself with the old coil you have probably found the issue.

[KGR1989]

From what Star mentioned 1982 year models don’t have a ballast resistor. I also don’t see any wiring or anything indicating that it was there and is now missing, but I will swap the coils to see if the problem persists. If it does then I’ll know it’s something else, and more than likely it’ll be that vacuum thing.

[Giovanni89]

it only doesn't require a ballast resistor if you are using an OEM style internally resisted coil. When you say Accel coil, I assume you mean an 8140 Super Stock. These coils are not internally resisted. If you run them on 12 volts, they will burn up. They are also oil filled for cooling. They want to be mounted vertically so that all of the windings are submerged in oil. Run it on 12 volts mounted sideways like the oem coil, and it won't last long. My experience is that they fail gradually, giving weak spark under load.
Changing the pickup in the distributor can also change your timing. It may just be over advanced. Verify that your base timing, mechanical advance, and vacuum advance are all good. I did have my mechanical advance stick once, and it gave a similar situation. If i snapped the throttle it would release the mechanical advance. If it revved up and down slowly, the advance would stick and my base timing was up around 18BTDC. It would start pinging like hell under a load.
One other thought, make sure that the vacuum solenoid you unplugged isn't connected to the vacuum advance in any way.
Good Luck!

[StarquestMan]

Sorry it took me so long to find my Chilton book, but better late than never i guess. Here is a picture of 82-84 ignition wiring. I see a device labeled "solenoid valve" that is most likely that black vacuum device near the coil. it is controlled by a relay labeled "ESS relay". Ill study this diagram later tonight when I have some time and see if I can come up with any scenarios that would cause issues with anything shorting something out. Giovanni has great points on the coil compatibility and the vacuum advance sticking etc.
82-84 D50 Ignition wiring.jpg