Weak Spark! SUCCESS!

[illegalFSJ]

My J10 won't even start anymore.
I was having trouble starting it a few days ago, and found that I wasn't getting spark to the plugs, but that I had spark getting to the distributor from the coil. Changed the cap and rotor, and it was a little better. Still hard to start, though.
The tune-up guy at work said I had weak spark, so that's what I'm going on. Said I probably needed a new coil, since that's what produces the spark. Got a new Standard coil, and with that one hooked up, I think the spark coming from the coil is even weaker than it was before, and the truck won't even come close to starting. (to watch the coil spark I just laid the coil wire on a valve cover and cranked the motor.) As I crank it, it'll spark a bit and then quit for a second and then spark a bit.
Any ideas?
Thanks...

[ November 03, 2003, 08:54 PM: Message edited by: illegalFSJ ]

[jeepsr4ever]

could be the selenoid, usually when a coil goes out it doesnt get weak

[illegalFSJ]

The starter solenoid? How? Why?

[ October 15, 2003, 08:50 PM: Message edited by: illegalFSJ ]

[Chevelleguy]

Replace the pickup coil and igniton module.

[illegalFSJ]

I was under the impression that if the ignition module went south, the coil would not throw out any spark. Is this incorrect?
Does the Prestolite distributor even have a pickup coil?

[letank]

77, what do you have in there?

i would measure the voltage at the coil.... may be the resistor wire...... is toast.... alternate would be to connect a direct wire to the + of the coil and see if you have improvments.... do it temporarily so yu do not toast the rest

Michel
74 wag

[illegalFSJ]

Um, every '77 I've owned has had the Prestolite Dist. It was points until '75, then Presto (BID)in '76-'77, then Motorcraft (Solid State) '78 on, I thought.
I can't find a resistor wire. Where is this?

[letank]

It is the wire from the firewall to the plus side of the coil..... somewhere along the wire there is a solder for the resistor wire and then another solder before the wire to the + side

on the older (points) you should have about 9 volts..... when the resistor wire gets old... you may barely have 7..... i bypassed mine and put a splice from the solenoid and a 1.32 ohm resistor or what is 1.28.... that i got at Napa

Alternately you can go direct with 12v for a short time

Michel
74 wag

[illegalFSJ]

OK, I put battery voltage straight to the coil, and it made no change in the spark. It's still very weak. So, what does this mean? Ignition moduale or pickup coil? Or something else?

[kjax]

I've had ignition modules act the same way... it's worth checking. Last time mine started going out, I was 300 miles from home. It made it, but sure was running like crap- weak spark- smelled like the choke was on. Went out completely a few weeks later. Could still be coil. Test resistance. Otherwise, suspect module or pickup.

[illegalFSJ]

OK, I finally found my manual, so it's time for some serious testing with the multimeter.
Thanks for the help!

[illegalFSJ]

OK, the coil tests out perfectly. It's still getting spark to the distributor, but none is getting to the plugs.

The pick-up coil tested at 1.5 ohms, and the spec is 1.6 to 2.4 ohms. So, technically, it's outta spec, but only by a very small amount. Think that little bit would cause no spark out to the plugs?

I tried to test the resistor wire ohms, but the digital mulitmeter readout kept jumping all over the place, from 0.00 to 7.5 to 5.2, etc.
Even thought the reading is kinda weird, I doubt it's the problem because it's not a voltage supply to the coil issue.
I applied direct battery voltage to the coil and cranked it, with still no spark to the plugs.

I guess I'll get a pick-up coil and ignition module tomorrow. Any other ideas?

[will e]

When I disconnet the primary wire from the coil on my rig the spark will jump right out of the top.

(I found this out the hard way when I put on a new timing cover and had TDC 360 degrees off!)

[kjax]

"OK, the coil tests out perfectly. It's still getting spark to the distributor, but none is getting to the plugs."

Maybe a bad cap, then. Or the wrong rotor?

[illegalFSJ]

Yeah, the cap or rotor was my first thought as well. I got a nice new cap and rotor from CarQuest, and I was sure to get the right parts.
At this point I think it has to be something in the distributor (pick-up coil) or an ignition module. I'll let y'all know tomorrow night how it turns out.

[illegalFSJ]

Installed new Ignition Moduale and pick-up coil. Still no change!
Spark out of the coil is still weak and erratic (like it misses a beat sometimes) and it's not making it to the spark plugs.
What is going on here!?!!?!??!?!?
I've replaced cap, rotor, coil, ignition moduale, pick-up coil. Great Googley MoogleyGreat Googley MoogleyGreat Googley Moogley!?
Makes no difference in spark quality when I apply direct battery voltage to the positive side of the coil. Stragely, today I noticed a whineing noise when I touched the jumper wire to the battery +, when the other end was at the coil. It sounded like it was coming from the distributor, so I took the cap off and tried again. Then it sounded like it was coming from the coil. Just a soft, but high-pitch whine. I dunno, maybe I was just disturbing the demons that have taken up residence in the truck.
Please help - I got a $200 ticket this morning in my POS Toyota for all kinds of safety violations. I tried to explain that I was only using this car until I got my Jeep running, but the state trooper was unsympathetic....

[Michael]

Have you checked you timing? It has to fire in time. Just an idea. Some spark will usually try to hit.

[illegalFSJ]

It's not the timing. I drove it home 15 miles last week, and it had a big ignition miss. Drove very poorly.
Just for fun, I went out and rotated the distributor in varying degrees of advance and retard to see if it would make any difference. It didn't change a thing...

[kjax]

I would still contend that if you have a good spark at the coil, and it's not getting to the plugs, then it must be cap/rotor. Or wire.

If it's not good at the coil... well, then you need to retest and t/s the ignition system again. Did you check output voltage at coil? Did it look like a decent spark from coil?

You know by now that it's a fairly short list of things to check. Give it another look/see. Good luck.

[will e]

How did you check the spark at the plugs?

[illegalFSJ]

Voltage at coil is 12.2 V. Coil is still throwing weak spark, weather with the old or new coil.
To check the spark at the plugs, I used a ST-125 spark tester. Just looks like a spark plug with a clip built onto it's side. Clip it onto a brake line or whatever and crank away.
I've been over the whole system several times and just can't find why it's not working properly.
I'll spend some more time on it this weekend, but if I can't make it work, I don't know what to do to get this truck running.

[SAustinwag]

bad distributor?? That's all it can be man. Well, either that or your timing cahin jumped real bad... can only be so many things ya know?

[letank]

test your HT lead and the coil lead as well which being shorter should be like a lot less... should not be over ? 15 or 18 Kohm... do not remember the exact value

Michel

[illegalFSJ]

OK, I'll go through the timing again in the morning, just to be sure it's on.
I tested the coil wire: 5.35 K ohms. I checked a few plug wires as well and got reading around 7-9 K ohms, so that should be fine.
What's the HT lead?

[illegalFSJ]

I think I found a pretty big clue to the problem this morning. I was checking the wiring harness (as a last resort, of course) when I found a burn mark in the plastic conduit. Apparently, it had rested on the exhaust manifold at some time in the past. I stripped the conduit off, and found a big sticky mess where all the wires in the harness had melted together. There were broken, frayed and exposed wires all burned together.
So, whaddya think? Bad news, huh?
I'll post in the "wanted" section for an engine wiring harness, since my wiring skills are questionable at best.

[Al Johnson]

Just pull the wires apart and use some electician's tape on them to insulate from the other wires. Then you will know whether that is your problem. If so, you can go ahead and replace the harness ($$$) or get in there and solder/shrink tube to repair.

Good luck!

[carrotman]

The wiring harness on my motorcycle burned up when I was 30 miles from home. No lights, but I made it home. 16 wires were melted together. Here's how to fix it. Get an all-purpose wiring tool that can crimp, cut , and strip. Get some 16-14 gauge insulated wire. Get some 16-14 gauge butt splices. Cut out the burned part and use the tool to strip about 1/4 inch insulation from all the unburned wires. Use the tool to crimp on the butt splices to each wire. So you will have butt splices on both sides of the unburned wires. Cut and strip 1/4 inch on both ends of the insulated wire to fit between the butt splices, and match up all the colored wires, ie. red to red, brown with yellow stripe to brown with yellow stripe. Tape them all together and tie it with cable ties so it won't fall on the exhaust. Goes faster than it reads, and much easier than a new harness.

[andy d]

i 2nd what Al J just said. what is the likelihood of finding a wiring harness in better shape than the one youve got? i spent a full day rehabbing the harness on my new 88. it was only 15 yrs old and the wires were cracked and brittle. your gonna be looking for a 25 yr old one....i used practically a whole roll of tape, a dozen butt splices and almost 15' of loom but the harness is working and run well away from the exhaust. much rather work on it one wire at a time than trying to figure out where everything goes.

[illegalFSJ]

Alright, alright, I'll try to fix the harness. What's better, using the butt connectors, or twisting the wires together and using heat shrink wrap?

[andy d]

twisting the wires together and soldering them is the best, but its a PITA. i have been using crimps successfully for years. after you make a crimp, tug on it to make sure it grabbed. they are color coded. red is 16-18 awg, blue is 14awg, yellow is 10-12 awg. heat shrink looks better than tape, but doesnt really protect any better.

[OldGrayGhost]

Man I had the exact problems with the exact ignition system. New Dis, new cap, new rotor, new coil, new module, fresh wires and plugs, new ignition switch, 2 months of pain, hate & discontent endless multimeter testing, and no OGG running. 70 bucks for semi clean HEI Dis and coil at junkyard, 25 bucks accel wires, 25 bucks for proper dizzy drive gear,2 hours of work, 1 shot of ether , S*%t canning worthless BID system in it's entirety PRICELESS!!! I know your pain, It's so easy to switch, you will get rid of all those pesky wires and be down to one 12v wire to the coil. I even cut the resitor wire and mounted a Ballast resistor. Life is good.

[illegalFSJ]

OGG, if the wiring repairs don't work I'll be forced to try another ignition system. I've spent so much time, money and energy on this BID system and plus I'm a stubborn SOB - but I do like to keep my trucks as close to factory as possible for a number of reasons.
And my logic tells me that the truck drove 117,000 miles with the BID system, so it can't be all bad.
If the wiring dosen't fix it, I have a points-style distributor from a '74 that I could try, or I could install a Motorcraft SSI unit from a '79 that I have hanging around. Haven't quite decided which way to go yet.

The thing that bugs me is that when I put a jumper wire from the positive terminal of the battery straight to the positive terminal of the coil, the weak spark condition did not change, which would imply that the cause was not in the wiring, right?
Oh well, I'll start on the wiring repairs tomorrow.

[kjax]

Depends. In the mess of melted wires, was the ignition box wires included? Assuming nothing burnt through, just separating the wires and keeping them from grounding should allow you to check if that's your issue. If the ign. box wires were fused together, you may end up replacing that...

I usually use crimp connectors... with solder and heat shrink. You can buy crimp connectors w/o the plactic covering, or remove the plastic covering and then solder. That's what I do with my stuff, anyway. My trick with it is that I solder the connector to the one wire, filling the connector completely with solder so that when I'm ready to connect the other wire to the joint, I just heat and push the wire in, without the need to add more solder.

[OldGrayGhost]

Originally posted by illegalFSJ:
OGG, if the wiring repairs don't work I'll be forced to try another ignition system. I've spent so much time, money and energy on this BID system and plus I'm a stubborn SOB - but I do like to keep my trucks as close to factory as possible for a number of reasons.
And my logic tells me that the truck drove 117,000 miles with the BID system, so it can't be all bad.
If the wiring dosen't fix it, I have a points-style distributor from a '74 that I could try, or I could install a Motorcraft SSI unit from a '79 that I have hanging around. Haven't quite decided which way to go yet.
I am with you on the "keep it stock" frame of mind and I was stubborn as a mule also (sat for 2 months). There is nothing at all exotic about the HEI setup, it IS stock on Chevy mills and was for years. The improvement in MPG's, driveability, cold starts and over all power is very noticable and my stuff (except for accell DIY wires) was junkyard fodder. Mine is a DD and I love a simple upgrade that improves overall performance. Mine went 136k with BID, many have gone more with less. You seem to have handle on it, at least you know you have options.

[SAustinwag]

Uhh, yeah.. that'l do it. I wouldn't attempt re-wiring the whole truck though...

[illegalFSJ]

OK, wiring is all fixed up. I cut out the burned parts and got it all fixed up nice and neat.
BUT, it still has a weak (almost non-existant) spark!
I guess I'll try a new distributor...?

[Rokcrler]

Illegal... whats the worst that can happen if its not the dist? For the $55 or so it costs with a lifetime warranty you cant go wrong. It did work for me

[illegalFSJ]

Alright man, I'll get a new distributor.

It's just getting depressing spending $68 for a moduale, $28 for a pick-up coil, $35 for a coil, $15 for a cap and rotor... and still no change in ignition.

[illegalFSJ]

What I don't understand is this: My current distributor has a new cap, rotor and pick-up coil, so how would a new distributor be better than what I have already? It dosen't have excessive shaft play, in fact, it is a rebuilt unit from a year or so ago.

[Michael]

Possibly the pick up coil you put in is bad...
that has happened to me more than once.

[onitsside]

Just a thought but how close is the bottom of the ignition coil to the intake manifold. Sometimes the coil slides down the bracket and can actually ground out on the intake. Let us know. Hope this helps.

[kjax]

"What I don't understand is this: My current distributor has a new cap, rotor and pick-up coil, so how would a new distributor be better than what I have already? It dosen't have excessive shaft play, in fact, it is a rebuilt unit from a year or so ago."

Exactly.

"Sometimes the coil slides down the bracket and can actually ground out on the intake."

Only if the case breaks.

[illegalFSJ]

Kjax - are you agreeing that replacing the distributor dosen't make sense, or agreeing with Rokcralr that I should replace it?

And the coil is suspended a half inch or so above the intake like it should be.

[kjax]

I'm agreeing that it would be pointless to change the the distrib. (hehehe)

A rather expensive way to replace the pickup.

[Rande]

How is the ground cable from the engine to the frame?

[kjax]

Really, the negative side of the battery ought to connect to both the engine and the body/frame.

illegalFSJ- you never stated how bad the melted wires were- i.e., were any of the ignition wires melted to the point that they could short? You stated in general, but never answered on the ignition wires (ECM).

It doesn't take much to blow the ecm. I'm not saying that's it, but the list of things to check and the wire to track is pretty short. I've been in your shoes before- for me it's usually been either a bad ecm or poor connections. Grounding to the ecm is always worth checking. I've rarely had problems with coils or pickups, but they go bad, too. Never rule out a brand new defective part. That happens, too.

[illegalFSJ]

I've got a good thick ground cable from the frame to the block in the stock location - around the motor mount.

The negative cable of the battery has a 10 gauge wire to the fenderwell and a 2 or 4 gauge (whatever is standard thickness for battery cables) to the engine block.

I agree with Kjax, the list of things it could be IS fairly short, yet seemingly impossible to fix.

The melted wires were still contained in the harness, and not shorting to the engine grounds. But, with all the melted insulation, they may have been crossing with each other. Each wire had a burned part about an inch and a half long, but none turned out to be broken. What I did was just cut out that part and crimp butt-connectors over the wires. There was a thick yellow and a thick red wire as well as the red with white stripe (coil positive) and a green (coil neg.) and the wires for the temp and oil pressure sensor.

I'll keep trying. I'll get this truck to run if it kills me.

Thanks for all the help so far...!

[kjax]

Thick yellow runs from starter solenoid to ammeter. Thick red runs from alt. to cab and has splice- runs to light switch, ammeter, ign., all over the place. Green wire from neg. side of coil should run back to ecm, red/white is hot with ignition on- runs to ecm and positive side of coil, blue and yellow from dist. connector run back to ecm, and the ground off ecm to body.

No doubt, anything shorting to ground is going to be a problem. Check your ecm connector and dist. connector- make sure there is good contact, nothing broken/loose there. Double check all the wiring associated with ignition in the engine compartment- in other words make sure that the wires running back from the dist. and green from coil back to ecm are good to go- no cracks in covering, and that you've got 12v at ecm and 12v at coil. Take ground off of body for ecm and make sure that's good and clean.

Aside from that, it's one of the three parts- ecm, coil, or pick-up (make sure it's gapped right). Test as necessary. If it's all good to this point, then you should be able to connect a plug to the coil and see good spark.

[onitsside]

Tested my spark on the j20 with 360 and it provides better spark if its farther away from the intake. Just my .02 I know the coil is sheilded to keep this from happening but it makes a difference in mine.

[illegalFSJ]

Kjax - thanks for the "walk-through" on what I need to test.
I'll be working on it tomorrow and Sunday if need be.
Thanks to everyone for all the advice!

[KivaKid]

Just to add to an earlier question:

The Prestolite/BID ignition system does not have a resistance wire or ballast/coil resistor. That is controlled in the module. I'm changing this system to points as we speak, and have to add the ballast resistor (1.35ohm) or buy a coil with it internally. I'm curious to see what you find, Illegal! Good luck!

[shredby4]

This may sound silly to some of you, but my vote is a weak battery, bad battery cable, or bad starter. I had a similar problem with my Jeepster. A near death starter can suck up every bit of available electricity while trying to crank your engine. Whenever I'd try to start it there was no spark unless I jumped it off with my other Jeep. Once started it would run fine though.

Watch your amps/voltage when you try to crank it. Try jumping it off too...see if it starts better.

PS... I replaced my coil too...then I replaced the stock replacement coil with an MSD Blaster 2. Worth every penny.

Try cleaning ALL connections too...including the grounds.

[illegalFSJ]

Shredby4 - you may have something there. I just checked for voltage to the "+" side of the coil, and to the igniton moduale. They both had full battery voltage - BUT battery voltage was only 11.25 volts. So, it may be just a charging system problem.
Tomorrow, I'll swap in a known strong battery out of my daily driver and if the truck starts up, I'll know it was a battery/alternator/charging system problem.
Of course, if that is what it turns out to be. I'm gonna feel pretty dumb for spending so much time, money and energy on the igniton system.

[Crash_AF]

Of course on the bright side, now you KNOW the entire ignition system is in great shape... smile.gif

Later,
Joe H

[andy d]

Originally posted by Crash_AF:
Of course on the bright side, now you KNOW the entire ignition system is in great shape... smile.gif

Later,
Joe His this Joe H, formerly of Montgomery AL?

[illegalFSJ]

Well, I tried putting the good battery from my daily driver into the truck to see if that would do any good, but nothing changed. Still a weak and erratic spark. Maybe that starter drawing too many amps on cranking?
I could swap the starter from my '78 wagoneer in and see if it does any good, but that wouldn't explain the big ignition miss when driving.

[Simple Kind of Man]

Just hang in there you'll get it I know you will!

[illegalFSJ]

I'm installing a points-type distributor out of a '73 360 tomorrow after work.
Who knows, maybe that'll make a difference. It'll eliminate the BID system entirely, which I'm starting to think may be a good idea.

[illegalFSJ]

SUCCESS!
The points-type distrubutor got the truck fired right up!
I can't believe I spent 3 weeks screwing around with the stupid BID system. I drove myself half nuts trying to figure out why it wasn't supplying enough voltage. Now, I just don't care anymore. It's running on points, so I couldn't care less why it didn't run on the BID system.

[Shaggin' Wagon]

Congrats on your success and stick-to-it-iveness (that a word?)!

[Qudawg]

Congrats! I know what a pain a project can become, especially after 3 weeks! what a headache!

[Crash_AF]

Originally posted by andy d:
is this Joe H, formerly of Montgomery AL?Nope, I'm from SC... never lived in AL.

Later,
Joe H