Ignition problem 1982 4G52

[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 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 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/part...gr-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 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 houseI 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 . 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