No spark on my 84 Ram.

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Lars

Lars

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My truck has been giving me fits lately with randomly not having spark. It has finally gotten to the point where it isn't firing up at all. While trying to track down the problem today I found the coil is seeing 5 volts in the run position, but only 8 while cranking. The contacts in the plugs on the alt/coil harness are corroded pretty bad, so I am thinking that is where I'm losing the volts I need (I think I should have at least 9 volts). The hall effect senor in the distributor is triggering, the ECU module fires up my Dart fine, and the ignition switch seems to be working fine.
 
12 volts to start Ballast resistor lowers that to about 7.9 in run.
Follow the the red Battery wire away from the alternator. If there is a connector near the rear of the right valve cover, check the red wire there.
Im just guessing since I dont know model, engine, etc..
 
Oh my bad (stupid brain). It is an 84 D150, pretty much the same ignition setup as an A body.
 
You may well have a concern. Rustle up a wiring diagram, and measure cranking voltage at the bulkhead "going into" the cab on the line feeding the ign switch, then check it on the wire leading to the resistor bypass AT THE COLUMN connector and see how those two look. If the column reading is somewhat lower than the first, then work back from there. If the ballast is somewhat lower than the column reading, then work between those two

What does it read (cranking) at the battery, starter relay?

I'd say what you have sounds pretty low
 
Get a ohm meter and check the second hot wire from battery to starter relay and from there to the starter too. You already know there is a voltage drop. Finding where the resistance that causes the drop is the fun part. Good luck
 
67Dart273 said:
You may well have a concern. Rustle up a wiring diagram, and measure cranking voltage at the bulkhead "going into" the cab on the line feeding the ign switch, then check it on the wire leading to the resistor bypass AT THE COLUMN connector and see how those two look. If the column reading is somewhat lower than the first, then work back from there. If the ballast is somewhat lower than the column reading, then work between those two

What does it read (cranking) at the battery, starter relay?

I'd say what you have sounds pretty low
Click to expand...

I checked the voltages at the column and bulkhead, they were fine, no serious drop. I also had the bulkhead connector apart a couple of times and there was only minor corrosion on it that I scraped off.

RedFish said:
Get a ohm meter and check the second hot wire from battery to starter relay and from there to the starter too. You already know there is a voltage drop. Finding where the resistance that causes the drop is the fun part. Good luck
Click to expand...

The truck spins over fine, I just don't have consistent spark. I verified this with my timing light, and with a screwdriver jammed into #1's plug wire while the wife was cranking.
 
Lars said:
The truck spins over fine, I just don't have consistent spark. I verified this with my timing light, and with a screwdriver jammed into #1's plug wire while the wife was cranking.
Click to expand...

I wasn't referring to the main battery cable that runs the starter. It's the other smaller one that is suspect.
 
RedFish said:
I wasn't referring to the main battery cable that runs the starter. It's the other smaller one that is suspect.
Click to expand...

Ah, no I haven't checked that one yet. Was going to mess with it some more today before work, but my alarm didn't go off. :p
 
Well it isn't the wiring to the coil. I went through the trouble of cutting out the plug and the voltage didn't change. Only then did I decide to check what my Dart does and it only see's 4 volts in run, and 5.25 volts while cranking. It fires off with no trouble with less voltage. Something I did find. When turning the key from the "run" position to the "off" position the truck will huff sometimes, like it is sparking. I verified this with my timing light with the mag clipped onto the coil wire. When I click from "run" to "off" it will give me a shot of light every time.

To complicate things I was trying to figure out the coil thing and I jumped a wire from the + of the battery to the + of the coil, then started cranking (I found the above problem with my timing light before this). Didn't make any difference, although afterwords I remembered a coil reads as a short, so might have fried my ignition box.
 
None of that makes any sense to me, especially the Dart starting on 5 volts. I dont know where you are measuring voltage though.
Maybe someone else can chime in with more help.
 
I have the + on my dmm on the + of the coil and the - of the dmm to the - of the coil.
 
Plus + on + side of coil or better yet somewhere before the coil. - goes on ground not - side of coil.
 
Try checking the ballast resistor to see what the voltage is going through it. Also check with your meter on the + side of the coil and chassis ground with the key it the on position. I have seen this happen many times over the years. There will be no power to the coil during cranking, only in the run position.
 
Lars said:
My truck has been giving me fits lately with randomly not having spark. It has finally gotten to the point where it isn't firing up at all. While trying to track down the problem today I found the coil is seeing 5 volts in the run position, but only 8 while cranking. The contacts in the plugs on the alt/coil harness are corroded pretty bad, so I am thinking that is where I'm losing the volts I need (I think I should have at least 9 volts). The hall effect senor in the distributor is triggering, the ECU module fires up my Dart fine, and the ignition switch seems to be working fine.
Click to expand...
Could be a body ground strap from the fire wall to the engine.Must have a good ground or it won,t fire.
 
RedFish said:
Plus + on + side of coil or better yet somewhere before the coil. - goes on ground not - side of coil.
Click to expand...

It see's 9.6 volts with the dmm on the + side of the coil, and the - side of the battery while cranking.

Traction Dynamics said:
Try checking the ballast resistor to see what the voltage is going through it. Also check with your meter on the + side of the coil and chassis ground with the key it the on position. I have seen this happen many times over the years. There will be no power to the coil during cranking, only in the run position.
Click to expand...

leroymoparrr said:
Could be a body ground strap from the fire wall to the engine.Must have a good ground or it won,t fire.
Click to expand...

I'm getting good voltage at the resistor, better then my Dart.

I was thinking a ground problem since it was so intermittent before now. I had a problem with the dash lights acting all stupid at random on the Dart last year and it turned out to be a ground that gave up the ghost.

I also noticed that after cranking the neg cable is pretty hot, where as the positive cable isn't. Which indicates resistance. I have the ground going to the block (head actually), then another strap running from that point to the frame. Been like that for a few years though, doesn't look corroded, but that doesn't really mean much.
 
9.6 is closer to run voltage than crank voltage.
The grond link from firewall to engine can effect ecm operation but nothing else ignition related. Maybe we should check inside the van. Knowing there are 12 volts into and out of the ignition switch will help narrow down the fault.
 
RedFish said:
9.6 is closer to run voltage than crank voltage.
The grond link from firewall to engine can effect ecm operation but nothing else ignition related. Maybe we should check inside the van. Knowing there are 12 volts into and out of the ignition switch will help narrow down the fault.
Click to expand...

Right before I left for work I remembered I have a spare ignition switch, so I swapped it out, but it still wouldn't fire. Although I might had cooked the ecm when I jumpered the coil to the battery, so I'll need to test it before I push any further.
 
It was the airgap in the distributor. Whoda thought. I pulled the distributor, someone on another board suggested I check it. Was at .030 when it should be at .006. I wonder how it got out of spec. Stabbed the dizzy back in and it fired right up. Go figure. Thanks for all the ideas guys!
 
Very strange. Did you not find anything else wrong in the distributor ?
 
My other thread disappeared, this issue cropped up again a few months ago. Still fighting it. I have the timing close, my timing light indicates that #1 is getting spark, new distributor, correct voltage at the coil during start/run sequence (at least the same as my Dart and it fires no problem). Old truck is driving me nuts. It does this every few years, just up and one day decides it isn't going to run.
 
I would go back to your old screwdriver in the spark plug wire trick, and make sure the sparks jump a gap of 1/4" or more with a good spark. A timing light may trip on a lot less spark energy than the fuel/air mixture when cold.

Fuel in the fuel tank? If there is spark, what have you done to look at the fuel to the egnine?
 
Carb is squirting fuel, has a little less then half a tank of fuel. Carb is less then a year old. Ran fine until this latest bout of no starts.
 
I don't know if 1984 had the ECU module or the later "Lean Burn Spark Computer". It sounds like an ECU since you said you swapped it with your Dart. A common problem is that the ECU body doesn't get a good ground. The sheet metal screws the factory used worked OK for the first 20 years or so, but might need a better ground today.
 
Swap out the mag pickup in the distributor with a new one, or the one from your dart. These can come and go, and play all kinds of intermittent spark issues. I chased your exact issue for a year, and after hundreds of dollars worth of ignition boxes and coils, it was the $16 mag pick-up, deciding to work when it felt like it.
 
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