1982 Power Ram 2.6L No spark from coil on hot restart

[wthom4]

Kind of a strange one that's driving me crazy. Truck starts right up cold. I can drive it all day as long as I don't turn it off. If I turn it off it will not restart--will crank but no spark from coil. I have changed the coil, changed the distributor (twice because I thought the first one must be faulty). I also added a ballast resistor thinking that might be a solution. (I don't believe my truck ever had a ballast resistor but I see the part on RockAuto). No improvement. Problem definitely seems to be heat related--starts right up when it is cold, might restart if I turn it off and right back on, def won't restart if it "heat soaks" for 10+ minutes. Any help would be most appreciated.

[85Ram50]

Starter solenoid?

[xboxrox]

VAPOR LOCK..? A fuel issue than can make restarting difficult BUT YOU VERIFIED NO SPARKS..?

Hope you find the problem soon

[wthom4]

Definitely no spark when cranking when hot

[wthom4]

As in starter solenoid causing no spark from coil when the truck is hot?

[SubGothius]

Starter solenoid is unrelated to ignition/spark. The only thing they'd have in common is that when the ignition key is turned to the Start position, it sends power to both the solenoid and the black+red wire at the ballast resistor. Pretty sure those are parallel wires, so a fault in one should not affect the other, and you're saying the starter does crank, so that rules out any problem with the solenoid anyway. The black+red wire should be connected to the same end of the ballast resistor as the wire to the coil; this bypasses the ballast while cranking to give a bit more oomph to the spark for initial start-up.

How did you verify no spark during hot restarts? Main spark test would be pulling the coil lead off the dizzy cap, then hold that wire terminal end not-quite-touching a ground while cranking to see if you witness a spark jumping that gap to ground.

You say you replaced the dizzy twice; was that installing a new dizzy both times, or just with used spares you had lying around? Seems unlikely multiple dizzys would have a bad ICM (which is integrated with the pickup trigger inside the dizzy), but if they were used spares, could be they were pulled in the first place because their ICM went bad. No ballast resistor might also explain why ICMs keep getting cooked, and a failing ICM could plausibly explain the heat-soak restart issue.

[85Ram50]

IDK I have had vehicles run when cold and fail to start when hot because of the starter solenoid. They would remain silent or click but no turn over.

[wthom4]

Yes, pulled coil wire from distributor and checked for spark to ground and found none (when cranking when hot). Lots of spark if cold start and starts immediately ( and runs great).
2 new distributors from RockAuto.

[xboxrox]

I might just bite the bullet and buy another coil it could be the problem 'n only way to tell is use another coil (new coil is best) AFTER that the next part I might throw at it would be the ICM spark trigger inside the distributor set gap 1986 Mitsubishi dist is .031" gap (If I remember correctly)

Maybe hand over hand inspect every inch of electrical wires under the hood (including the battery cables & main harness fuses located near the battery) ~ using a DMM & 12V test light

I recently tested my coil & ICM 'n they both were within proper OHM spec per Haynes manual (but my truck ran like crap after warming up) so I installed a new coil AND DANG that was the fix..! An oil filled coil should be mounted upright much as possible AND an epoxy filled coil can be mounted horizontally (sp?)

Ensure the METAL END of the high tension spark plug wire is fully & securely inserted into the coil outlet !!

Eventually the FIX will happen

[SubGothius]

Yeah, I concur it may be a failing coil. They can have transient heat-soak issues when they start going bad, so they might test fine cold or on the bench, but thermal expansion as they heat up can cause a short or open circuit in a failing winding, which resolves again once it cools down.

Threw me off that yours keeps running as long as you like after a cold start. I can only guess maybe airflow thru the engine bay was keeping the coil just-barely not-quite hot enough to cause the open/short, but then once it sits a bit with all that residual heat trapped underhood, that tips it over the line.

I really like the Herko B108 coil I got for my '87; it's the epoxy-potted "transformer brick" type (vs. the oil-filled canister type), comes with a ballast resistor, and pretty reasonably priced (e.g. on eBay). I disassembled the mounting bracket to flip the coil around for easier/tidier wire routing, not sure if that'd be any concern with your '82, so just a tip that's something you could do if need be.

[wthom4]

I'm not opposed to buying another coil, but I did already replace it. And the one I replaced was only about a year old. The Herko says it is for 1987-89 (not my '82). That said, I'm desperate so if you think it will work I can try.

[tortron]

Have had a few coils die over the years, last car one had a date code of 1963 and was warming up and missfiring after about 15 mins driving, so i got my moneys worth out of it. Last motorcycle ones were NLA and had big visible splits down the sides, but were ok if you smeared silicon all down it incase it rained (lucky i could make some after market harley ones fit in the same spot with a little bending).

sometimes, when it wont start, you can dump some cool water on the coil (after you have watersealed the connections), and it will start again. Showing that they are heating, expanding, and failing.
Another point is, you can make a spark easier in the open air than you can under compression, so the spark test can sometimes be misleading if the system is marginal



You will be fine with any replacement coil, they all do the same thing on older cars the "hot" performance ones arent really needed and seem to cause more issues, just make sure its the right voltage and is a ballast or non ballast setup as required

[wthom4]

I already switched out my 1 year old Accel coil for a Duralast and saw no improvement. I don’t think there was really anything wrong with the Accel coil and I’m skeptical that the new Duralast is somehow faulty. I feel like it’s something with the distributor but I’m on my second one of those (both new from RockAuto). Feels like distributor is not telling coil to fire when the truck is hot. When cold it starts right up and runs great.

[wthom4]

Anyone think replacing the starter relay I see just above the fuse box could possibly do anything good for me? Also, I'm thinking about buying yet another--it'll be my 3rd--distributor. Is that crazy? I could also buy and try yet another coil. I'm at a complete loss as to what could be going on here

[SubGothius]

I had an Accel coil on a different vehicle that failed at a bit over a year old, just out of warranty lol. Funny thing, I'd installed it as preventive maintenance, as that car still had its 30 year old stock coil. Once I determined the Accel coil failed, I put the original stock coil back in, still running fine another decade-plus later.

As for Duralast... those auto-parts chain house brands can be a real crapshoot sometimes. Even their "lifetime warranty" stuff often means you're just buying into a lifetime supply of free replacement units just as crappy as the first one they sell you that fails a year or two into service.

[wthom4]

Changing coil was “preventative.” Same with distributor. Wish I could have a do over on those 2 decisions. Unfortunately, I didn’t keep the old parts to put back in.

[wthom4]

Hoping to keep this thread alive. Problem continues and I am at a loss at to how to fix. I have found a junkyard distributor in Portland OR--which will at least be OEM design--but still trying to convince pick-and-pull to ship it to me. Changing coils (again) had no effect. (I'm pretty sure I've ruled out the ignition switch as a source of the problem, btw.)

[camoit]

So is it getting power to the + side of the coil when cranking?
next have you changed the puckup / ignition module inside the distributor?
with my 1980. It would just fail and not start. 100 bucks later and a quick swap of the module it was running.
but every time it failed. I would get home and that was it.

[wthom4]

I’m 99.9% certain it’s getting power to the + side. It’s been a bit since I tested so I will test again this weekend. I think it’s likely the ICM inside the distributor but the distributors I’ve bought from rockauto look different than oem and I haven’t quite figured out how to change it. That said, I’m on my second distributor from rockauto so also on my second ICM.

[SubGothius]

The ICM can be replaced by itself; just two screws holding it in place on the advance plate inside the dizzy. RockAuto has several to choose from, listed under Ignition > Ignition Control Module (ICM). Snap a photo of the wiring connections on the old one before you remove it, so you can be sure of replicating that with the new one. They should come with a packet of thermal paste to apply between the ICM base and the plate it mounts to. An even paper-thin coat should be fine; it just fills the microscopic gaps between the metal-to-metal mating surfaces for better heat transfer. Use a feeler gauge to set the gap between the ICM sensor head and reluctor teeth on the dizzy shaft, should be gapped at 0.031" on an '84-89 2.6L. (The '86-89 2.0L used a different dizzy/ICM, gap there should be 0.008-0.015".)

[FMS88]

Got a volt/ohm meter? Check voltages at the coil and the ceramic resistor. Check the resistance and continuity of the ceramic resistor and the ignition wires including any ground wires. Do this testing when the engine's cold and then when it's hot and the no start condition is present. Any difference in measurements could point to the fault's location. Also, check the fuseable link on the driver's wheel well toward the firewall.

[wthom4]

I think I solved this issue. It seems there is a compatability issue with the first 2 distributors I ordered from RockAuto. Brand was SKP. I bit the bullet and ordered a 3rd dizzy, this time brand was Autoline, and it worked immediately. Hot start issue no longer an issue. Fires right up. I always believed the issue was ICM, but ICM in SKP distributors didn’t look like OE ICM so I was unsure how to replace just that. Thanks to all for your suggestions. This community is a great resource.

[xboxrox]

wthom4

What source had the Autoline dizzy..? A new or rebuilt unit..?
Thanks for sharing the fix my friend..! Good Job..!
BTW I read somewhere online that even if a coil tests sat for ohms it can be a bad coil (that was my exact issue 'n fix)

[wthom4]

Thanks. The Autoline is also from RockAuto. It is a remanufactured unit that looks just like OEM. The truck is running great.

[SubGothius]

BTW I read somewhere online that even if a coil tests sat for ohms it can be a bad coil (that was my exact issue 'n fix)

Yup, all you can tell with confidence is a coil that tests bad in any scenario is definitely bad, but a coil can test fine at rest or on the bench, yet still develop a fault as it heats up in operation, which may go away when it cools down again.