Ignition problem 1982 4G52

[KGR1989]

Alright, so the other night I was driving on the highway and suddenly it backfired and it lost all power. Still had lights and all though. Coasted to the side of the road and checked what I could. Friend came with a trailer to get me and brought it to his place where we've been working on it some the past few days.

So we've followed it all down to the ignition system. Tested the coil and wasn't getting anything from it so went ahead and replaced it, but still the same result. So pulled off the cap and rotor button and cleaned up them. They're not in perfect shape and I'm going to replace them, but I don't believe that it's the problem because the coil isn't even getting signal to fire.

Now, I've never messed with anything this old, but behind the rotor button there's what looks to be an early style ignition control module that's kind of like a small coil that goes around the shaft of the distributor and screws in at two points and has two wires that come off of it going back to the coil which I assume is for the signal to fire? Is there a way to test this? It kind of looks like a points eliminator?

Thanks in advance and excuse my lack of knowledge on the older stuff lol.

[geezer101]

Any chance you can post a pic of the distributor up for us? The only time I've ever messed with a 4G52, it had a points distributor in it. Judging by what you've said, it sounds like the igniter/pick up in the distributor died. You can swap the distributor from a 4G54 into it.

[KGR1989]

I'll have to take one tomorrow. I don't think the actual distributor is bad, but I'm not sure of how to test it. From what I can understand about it just by looking at how it's wired it looks like the pickup/igniter sends a signal of some kind to the coil. The two wires that come off of it one goes to the negative side of the coil and the other goes to the positive.

Is the distributor in the 4G54 a newer design? I've never seen a points style distributor, but I don't think this is one. My dad said that it seems like the part I'm describing is a points eliminator of some sort, but a factory style of it. To me it kind of looks like an early style of an ICM (ignition control module). I'll post a picture tomorrow though and guess I'll go from there.

[KGR1989]

So, I found the actual part. It's a distributor ignition pickup. Here's a picture of it. It sits behind where the rotor button mounts to and to take it off you just take off the bolt in the center for the shaft that the button mounts to.https://cdn11.bigcommerce.com/s-z4od74zs7s/images/stencil/1280x1280/products/166343/357030/410-2MmVHiL__79045.1571948239.jpg?c=1&imbypass=on

[KGR1989]

I just realized that it blew up the picture and didn't fit it to the forum sizing...my bad lol
https://cdn11.bigcommerce.com/s-z4od74zs7s/images/stencil/50x50/products/166343/357030/410-2MmVHiL__79045.1571948239.jpg?c=1 There's a smaller one lol

[KGR1989]

Found it on rockauto, but it's also showing a separate ignition control module that it says is located inside the distributor, but I don't remember seeing one? Is it possible that some engine variants had one and some didn't? Sorry for all the questions

[StarquestMan]

I agree with geezer, it sounds like the igniter is bad. they go by different names like igniter/icm/coil pickup etc. its job is basically like you mentioned it being a replacement for points in an older distributor. its a self contained module that contains a pickup coil and some circuitry to switch on and off ground to the coil to generate spark. one wire powers the circuitry inside and the other is coil ground if i remember correctly. there may be a way to test it but ill have to check my service manual for my 87' that uses a very similar module. i had one die on me and it acted like a dead coil. if you replace it you may need to set the gap between it and the rotor for it to work properly.

[StarquestMan]

i studied your picture better and realized how your pickup coil is separate from the icm on your distributor. you should be able to check the coil with an ohm meter and if it checks out than the icm is probably bad. i bet that the plug in icm part of it is bad but the coil could have gone too so i would check it out too

[geezer101]

Even if the it's only the coil, there should be some life in it. It will misfire and die at higher rpm, or alternatively it will quit when it gets hot (classic symptom of a cracked ballast resistor) If the coil is original, it will be really tired - a coil normally lasts about 10 years before it starts to break down.

[KGR1989]

Ah, ok that all makes sense. I went ahead and ordered a few things from rockauto since it was pretty cheap and can't hurt to replace it all. Basically the only thing I will have that isn't new in my ignition system will be the actual distributor itself and I spent around $55 shipped to me for it all.

When it gave out it backfired pretty loud one time and then just lost all power. The actual ignition coil was replaced at some point with an off brand "performance" style one. It looks to be pretty old also. The pickup coil that I was mentioning earlier was the original part, so it's nearing 40 years old.

If this doesn't fix it then the only other thing it could be is the actual distributor, I think...I'll have new plugs, wires, pickup coil, cap, rotor, and ignition coil. Beyond that I don't think there is anything else other than the distributor, correct me if I'm wrong though.

[geezer101]

Once you have replaced anything electrical related to the ignition system, you're only left with the distributor itself. The counter weights for the advance can have the springs break or come off which causes erratic ignition advance or the vac advance servo can split which will leave the engine response down on initial open throttle. The advance mechanism can also gum up with junk which will prevent the ignition curve from ramping on throttle.

[KGR1989]

Alright, so the parts came in last night and I just went to install them and I'm still getting no spark. I'm not entirely sure I've got everything hooked up to the coil properly though. The old coil is labeled (+) and (dist) which I assume the distributor is acting as a ground for the coil? The new coil is labeled (+) and (-) and I have the main power and the ignition wired to the (+) side and the two signal wires from the pickup coil and the tach to the (-) side.

Of the two wires off of the pickup coil, one of them has a rubber nut cap to slide over the top of the ignition coil stud that it goes on. So that one can't be hooked up to the (+) side because the main power has one of those as well and they can't both go on the same side. I've switched the second wire coming off of the pickup coil to the (+) side, but still no spark.

Now, the new pickup coil I bought from RockAuto did not have a new ICM I guess you would call it. It's just the actual wires with the coil itself that goes around the distributor shaft and out the side. Having a hard time finding the ICM online and parts stores aren't being much help either.

I'm just hoping that someone will tell me I've got it hooked up wrong and that will solve the issue, otherwise I'll have to search to find the ICM and hope that it's the problem.

Here's a picture of how I have it wired up. Hopefully it's shown a bit larger in the actual reply than it's currently showing on my screen.

23760

[StarquestMan]

I think you may have two problems. i see right off the bat that both wires coming from the distributor are tied to coil ground (labeled "dist" on your old coil) the black wire with the white stripe coming from the distributor should be paired with the black wire with white stripe from the harness side. the black wire with white stripe on the harness side is your 12v supply to the coil and the ICM needs power to function too so it has a matching color wire that sends power to it. the blue wire is correct in that it provides a ground path through the ICM and im not sure what the light and dark brown wires go to (im guessing the dark brown is going to a tach and/or computer ignition signal and light brown being B+ for said computer?). the second thing is probably a bad ICM itself but the wiring should be corrected first. if moving the ICM black w/white stripe over to the coil + doesn't bring back spark keep the two black wires on the + terminal and replace the ICM

here is the icm link
https://www.rockauto.com/en/catalog/dodge,1982,d50+pickup,2.0l+122cid+l4,1087310,ignit ion,ignition+control+module+(icm),7172

[KGR1989]

Ah, awesome! I'm gonna go try it out right now and I'll post back with the results. Hoping it will fire up lol. Thanks for the ICM link too! Not sure why I couldn't find it?

[KGR1989]

No luck, so I'll order a new ICM. Pretty sure that's all it could be now other than the actual distributor, but I don't think that's the problem. Unless there's something else I'm missing that I haven't replaced that is.

[KGR1989]

Ok, so the ICM came in today. I installed it and still no spark off of the coil. I paired the wires as Starquest mentioned and also tested to make sure I'm getting power to the coil and I am getting right at 12V to the coil. Swapped the new coil out for the old one just to see if maybe the new one is bad and still the same result.

So, new cap, rotor, pickup coil, and ICM and it's still not getting spark from the coil? What am I missing? I might be wrong, but if the ignition switch were bad then the engine wouldn't turn over right? It can't be a bad distributor could it? If it were bad it'd still get spark off the coil, right? Also, to test the coil spark I have done it a few different ways. First with the wire off the coil attached to a spark plug. Then with the wire with no plug, and then another time with my wife turning it over and I was looking inside of where the wire plugs in but with no wire.

I'm stuck lol :bang: :confused:

[Giovanni89]

A multi meter will be your friend here. Start simple. Turn the ignition to the on position. You should have about 7-9 volts at the +side of the coil. There are usually two wires from the ignition switch. One provides 12 volts to the ballast resistor when the key is in the on position, which feeds 7-9 volts or so to the coil. The other provides 12 volts directly to the coil when the key is in the start position (this is often connected to the second side of the ballast resistor and not directly to the coil). This is because the starter drops your battery voltage, and the ballast resistor would drop the voltage too low to get a good spark.
I'm not familiar with the 4g52, but I'm not sure why there are three wires to the negative side of the coil. I would think there would only be one (two if you have a tachometer hooked up). The coil grounding wire from the icm. If the coil is constantly grounded it won't throw a spark. The way they work, They are grounded, and build up a magnetic flux in the primary winding. When the "points" or icm open, the current stops passing through the primary coil. The built up flux has nowhere to go, so the flux field collapses into the secondary windings, and on the the spark plug. The ratio of secondary to primary windings gives you the massive voltage step up, like a transformer.

[travhous]

Black/White from distributor +
Blue from distributor -
Black/white harness (ign.) +
Small brown (tach) -
Large brown (starter?) +

When the ignition key is turned to the start position it cuts power to the entire truck. The coil then gets its power from the starter while it is cranking. I'm guessing that the larger brown wire is from the starter.

There should be a ballast resistor also that is missing, although that is not your current issue. There's a good chance that not having the resistor burned up the igniter in the distributor originally.

[geezer101]

+1 on the ballast resistor. Not having one in place will drastically shorten the life of the ignition components. If you're getting power into the coil, then the problem is between the coil and distributor. No power to the coil, there's something up from the ignition switch.

[KGR1989]

Alright, I'll try flipping the browns around like you mentioned and see if that works. Not sure where the resistor is supposed to be. I bought the truck like this and the previous owner didn't do much to it in all the years he owned it. I asked him about the ignition situation and he said he hasn't done anything with the coil or ignition in the time he owned it which was 10+ years.

I do know that there's 12V to the (+) side of the coil when the key is in the on position and when it's being cranked it doesn't change. Tested with my friend the multimeter lol. I do have a tach hooked up and I *think* it's the small brown wire with the newer red end on it that's in that picture I posted.

Currently I have it as follows.
Black/white from dist. to (+)
Blue from dist to (-)
Black/white from harness (+)
Small brown from harness (+)
Small brown with red end (-) and I *think* this is for the tach

I'll have to reconfirm that it's for the tach tomorrow. It's currently 1AM and raining.

Really appreciate the help on this though. Been about 2 1/2 weeks since I've had it running and I'm missing my little beater truck lol. Wife isn't too happy either with all the broken down cars we have. Currently we own 5 vehicles and 2 are running LOL. My Trans Am's oil pump took a dump on me back in September and I have yet to drop the oil pan and repair it and I've got an older Honda Accord that has bad alternator (in a horrible spot) and my wife lost the keys to it :shakehead: SO I've been driving my Miata around until the truck is back up. I really hope my car luck gets better in the new year/decade :lmao:

[travhous]

At some point there should have been 2 positive wires, one on each side of the ballast. One would have been hot when the starter was spinning and the other while the key was on. Whoever removed the ballast may tied some wiring together elsewhere. I would double check the black/White from the harness and make sure you getting power with the starter is cranking. If not check the brown with red crimp.

Do you have a factory tach or aftermarket?

If it is a factory tach I would assume the smaller wire from the harness goes to the tach.

The brown wire with the red crimp has me stumped. Where does it run to?

[travhous]

23801

[KGR1989]

Well then, it's obvious mine is missing something LOL, but it was working without it before so I doubt that's the reason it isn't currently running. I'll definitely get that though and after I get it running I'll wire it all up properly.

It's been raining all day long so I haven't gone to verify which wire goes where, but I'm pretty sure I remember the small brown wire with the red connector going to the tach through the firewall. The other brown wire goes into the harness.

So looking at your picture it looks like power goes to both sides of that ballast, right? One source from the ignition and the other from the starter I assume as mentioned before? Then there's a jumper wire to the coil? Basically mine seems to be configured the same, just without the power input from the starter and no ballast setup. Tomorrow's weather will be better so after I get home from work I'll verify which wires do what, I'll check all the wires for power separately to verify which ones are giving power, and I'll see if I can come up with any other configurations that would make sense to try.

My dad keeps saying I need to find out if there's a separate ignition switch and see if it's bad. I guess the way to test the ignition switch would be to have my wife turn it over while I use a multimeter on the signal wire, correct? Also, wouldn't the engine not turn over if the switch was bad and would it have shut off randomly while driving? I would assume that the signal from it is only to start and not to continuously run.

[StarquestMan]

Hang on! sorry for the delay, ive been super busy with school. it appears that they didn't start using a ballast resistor until 83 or 84, i looked for a wiring diagram but could not find one. I looked up a coil on Napas website and it shows one with "No External Resistor Required" printed on it. I can find ballast resistors for 84-86 trucks and 87-89 trucks with a quick google search but all the rest are just generic universal type. Unfortunately I don't have a parts catalog that covers 82 to confirm it 100% but im pretty sure yours doesn't need the ballast resistor, assuming you ordered a coil specified for an 82. do either coils have any markings on them mentioning ballast resistors? like others said the heavy brown wire that was added could be a work around for a flaky ignition+ contact in the ignition switch when turned to the start position. if all that fails check the connections between the ICM and the pickup coil/wire assembly. also make sure the gap between the rotor and pickup coil are close enough to trigger the ICM properly.

[KGR1989]

Alright, so I did some messing around and testing today after work and here's what I've got.

That brown wire with the red end goes to the tach. The other brown wire is the signal from the ignition switch. When I turn the key I am reading ~0.20V from the ignition switch. That seems a little low doesn't it? The black with white stripe wire from the harness is power and it's reading 11.3V. When it's all hooked up to the coil it's reading 11.3V on the (+) side of the coil and it's also reading roughly the same on the (-). I thought this was odd. Shouldn't the (-) side read nothing since it acts as a ground for the ignition system? I switched back to the old ignition coil and it's the same result on it as well. Correct me if I'm wrong please lol I'm no expert.

So far I've got a new distributor cap, rotor button, pickup coil, ICM, wires, spark plugs, and coil and I'm not even remotely seeing a spark from the system at all. :questionmarks: :helpsign:

[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 :shrug:

[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? 23825

[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...:shrug:) 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!23826

[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.
24034

[StarquestMan]

Well after lots of digging I cant figure out what that vacuum solenoid does? its definitely a valve though as opposed to a switch with contacts. the diagram below it for 79-81 has the same valve but labeled as "ESS solenoid" so that ESS relay in the 82-84 diagram is solely responsible for controlling that and nothing else. Heck I cant even figure out what ESS stands for:scratchheadyellow: since you say that that solenoid valve gets hot when plugged in and reads like a closed switch on a multimeter, I'm going to assume that it is shorted. since it is essentially connected across the coil but with a relay in between, it being shorted will pull the coil power down which killed your spark. this is a bit off subject but I honestly cant figure out why there even is a relay for the ESS solenoid since power flowing to both the relay and the solenoid is switched by the ignition switch. I think now that your truck is running without that part being connected the issue you will have with your spark should be along the lines of what Giovanni and Geezer are mentioning with the coil resistance and cooling. Hopefully someone will know what the deal with that solenoid is for. strangely it needs an ignition pulse the way its ground is tied with coil negative, which may be part of the reason it failed. It looks like it probably gets a high voltage kick back like a tachometer would which would probably break down the insulation on the windings over its 35+ year life;) I wonder if this is just a basic valve like an A/C idle up valve? that would make finding a replacement much easier. Maybe it just functions as some sort of emissions device and can be removed much like a persons appendix?

[geezer101]

The fuel cut solenoid in the electrical diagram is the 'fuel cut solenoid' on the side of the Mikuni carb (no power, disables fuel flow, no run on...) The 'thingy' is a electrical vacuum switch and not a control solenoid as there's no path for the vacuum to travel to once it's activated/deactivated and there isn't an obvious electromechanical assembly that would indicate it requires power to redirect vacuum.

So it's "apply vacuum, connect circuit" but for what purpose - got me beat :shrug: I've looked up 'ESS' for a reference and came up empty handed.

[StarquestMan]

I noticed the fuel cut and ball vent valves on the diagram as well. the vacuum device in question is shown on the diagram as having a coil inside it like the ball vent valve and fuel cut valve. I think the reason that there is only one vacuum line going too it is that it just releases external air into the vacuum line.

[StarquestMan]

I studied the pictures of that little device and im betting that cylindrical portion of that solenoid that is towards the engine side of the vacuum port is a mini cotton filter to allow air in. kinda like the one found on the 4 port thermo valves found on later trucks. I know the 2 port vacuum valve for the AC idle up on my 87 has a little filter too to let air back into the throttle opener when the AC cycles off to let the throttle opener release.

[StarquestMan]

I think I may have found the part number, MD006209. all the websites only go back to 84 but that should be it. it's number 18 in the diagram here https://www.moparpartsgiant.com/parts-list/1984-dodge-ram-50/emission-systems-egr-system.html

[KGR1989]

Man, you guys sure do help a lot! Glad to have a great group to turn to when I have issues.

I scrolled down to #18 and saw it was discontinued unfortunately. Did a quick google search for it and only came up with two results for it. One was the link you found and the other is one selling it for $6,000 of some random currency LOL, but it doesn't even have a picture.

Had my daughters 4th birthday party today with 65 people at our house :shootself: SO as you can imagine I didn't have time to do anything at all. Family is up tonight and leaving tomorrow morning. So long as the weather isn't too bad I'll swap the coil out for the old one that didn't have this issue, then I'll take it for a spin to see if the problem replicates. If it does then I can eliminate that being a problem, if not then I'll just leave it on there and return this one lol. I hope a simple swap back to the old coil resolves the issue because it seems this little vacuum switch might be trouble to find.

Really do appreciate all the research and time you all have put into helping me figure out this. Can't wait to have my little truck healthy again and zipping me back and fourth to work.

[StarquestMan]

Oh man, I cant imagine having 65 people at my house:shock:I left that part number for you mostly for reference for you and anyone who sees this in the future and to show that they used them up until 84 at least. This way you can do a search around different junk yards and know what years have it, basically 82-84 for sure and probably 79-81 since they had a similar setup just minus the bowl vent valve. hopefully someone here will have one or you can check car-part.com ,it has helped me find some obscure parts before, just search for a common part on a D50 like an alternator or something and find ads with pictures of the truck to see if it has the part you need and give the yard a call and cross your fingers that they have not crushed the truck already :fingerscrossed:. most of the yards don't list the more obscure parts so doing a search that way should turn up something. I have found that now that I have found that site I spend way too much time killing time looking at parts so be careful :lmao: