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Discussion Starter · #1 ·
Hey guys, I can get my 87' 318 rc to start. It's been running great for a long time now but when I went to start it this morning, it wouldn't fire. I checked for spark, and it's not getting any. Here's what I've figured out so far. I checked the ballast resistor by jumping the leads and trying a new resistor, doesn't seem to be a problem there. Power goes in one end and out the other. I gapped the pick-up coil (single pick-up) and checked the dist cap and rotor, no prob there. I'm sure I'm missing something really obvious, and I'm not done looking over it yet, but any help would be greatly appreciated. Thanks

Dan
 

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Check for 12+ volts to the coil when the key is in start position, and about 8 volts to the coil when in run position....

But, you're right, it is bedtime ! Good luck in the AM ;)
 

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Is there a module under the Brake booster on the fire wall? That was the exact problem I was having with my 84 Ram P/U. Not sure if theres one on the 86 but if there is I'l bet thats it. Your explanation is 100% description of the problem I had.
 

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It could be, but better to go thru a system of checks 1st before replacing 6 things and then the right thing.
 

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I agree, however if it does point to that module be sure to get an after market one. The dealer wanted $94 and I got it at Canadian Tire for $36, No problems so far and it's been 2 yearsish. You might want to remove the old module and clean it up on the back side and the fire wall to ensure a good ground (I think some had a little ground wire to one of the module mounting bolts) then put it back on and try it, and check your vehicle ground as well to the frame for a couple quick easy things to try before forking out cash for stuff. These things have been known to cause problems in a Mopar.
 

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Discussion Starter · #11 ·
I'm pretty sure you're talking about the ECU, and yeah, it might turn out to be the problem. I'm gonna go ring the bell on round 2 here in a minute. I have a spare ecu and a spare coil to try.

Thanks again

Dan
 

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Discussion Starter · #12 ·
Tried the spare ECU, and no jazz. Couldn't find the spare coil, but I held the coil wire near an engine ground with the key on, and grounded the negative terminal of the coil; no spark. Am I correct in assuming the coil may be the problem?

Dan
 

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Do you have 1 or 2 pickup assemblies in the distributor? Take a meter and measure resistence of the pickup/s at the 2 wires coming from them...should be 150 to 900 ohms. If the pick up is defective there will be no spark.:)
 

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Discussion Starter · #16 ·
I just went and re-checked it, and found something I had missed before. With the key on the negative side of the coil sparks when I disconnect it. This to me seems wrong. When I take the lead off completely, and try the coil test again, viola, we have spark. I'm going to go and pull the connector off the ECU. If the negative coil lead is still grounding out, I figure I'll be hunting for a short somewhere. Thanks for all the help guys, and I'm still very open to suggestions ;D

Dan
 

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Discussion Starter · #17 ·
Ok, here's what I have as of now. with all wires connected where they're supposed to be, I hold the coil to cap wire near a ground and ground the negative coil terminal with a jumper, I get nothing. If I unplug the ECU and do the same thing, I get spark. The same thing happens regardless of whether the pickup coil is connected or not. Am I wrong to assume I should go buy a mopar orange box and pitch the jobber ECU I have on there now, or is there something I missed?
Thanks again for being patient guys, I really appreciate it.

Dan
 

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Why are you grounding the negative coil terminal? Grounding that would prevent the spark.

Edit: (I was thinking you were doing this as you cranked it, was I wrong?)
Just to back up a bit: The coil is fired when ground is interrupted NOT when it is grounded.
Before a spark is needed, the coil is actually grounded (via the negative coil wire and the ECU) This is allowing voltage to build up in the coil primary. When a spark is needed, the ECU interrupts the ground (coil -) and this causes a rapid decelleration of current in the coil primary resulting in a spark.
 

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Discussion Starter · #19 ·
Ok, update. Although I never want to see another multi-meter again, I found the gremlin. I traced it to an open circuit in the pick-up coil which turned out to be a damaged wire right where it connects to the pick-up coil. I replaced the pick-up coil and low and behold, we have fire power ;D It now runs, but I've run into a whole new problem. I can't get the p/u coil-to-reluctor gap right to save my life. From what I can tell, something in the distributor (probably either the shaft or the pick-up plate) is bent loose or otherwise screwed up. I had the gap as wide as .010"(4 thou over spec) and while it seemed to be gapped way too wide at idle, as soon as I got on the throttle and got the vacuum advance pulling, I could hear the point on the p/u coil rattling off of the reluctor. It wasn't a light tapping either, it sounded like a friggin rattle snake under my hood. :-X
The distributor I have right now is a reman unit that seems to have more play than it should, and I've always kinda noticed a slight miss at idle, so in light of recent events, I'm seriously considering some upgrades to my ignition system, starting with the distributor.
Thanks again for all the help guys, you were steering me in the right direction the whole way. And Chump was spot on with paying extra attention to the pick-up coil {cool}

Dan
 

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I have had bad luck with reman distributors too, (you should try to set the gap on a dual pickup and a shaft with too much play!). That was the main reason I got an MSD distributor, you don't even need to adjust the air gap!
Just to cover all of the bases first, did you use a brass feeler gauge to gap it with? It can be difficult to gap it properly with a steel gauge because of the magnetism.
 
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