If I can help via the phone shoot me a PM
Not getting spark-towed it home
- Thread starter standup303
- Start date
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Mattax
Just the facts, ma'am
You need to compare that to the supply voltage while cranking.
Mattax
Just the facts, ma'am
If it around 10.5 V at the battery it would show the problem is not in the wiring.
We know for sure its not 12 Volts during start.
if there is a big difference, then check at some other accessible locations along the flow path.
standup303
Well-Known Member
Thanks I may take you up on that this weekend. I only had 20 minutes but completely unplugged the “key on” blue wire and the blue with brown wire from the ballast. This got me 11v at the coil under crank. So the ballast is causing about 2v drop even on the “start” circuit. But I have no negative under cranking between + and - on coil. I have a dedicated neg between the brand new ECU housing and battery for troubleshooting. Could it be something with the pickup in the distributor not closing negative side of the coil? I’ll keep digging.
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I don't know what you mean by negative. Please stop trying to troubleshoot by unplugging stuff. This changes the circuit and may introduce unwanted situations.
With the key in "run" the coil NEG should be very low to ground, perhaps 1/2--2V and no higher. This shows that the coil is drawing current at rest, with key "on."
TRY THIS and I'm surprised no one has said so. "Rig" an alligator clip wire between a battery source, such as the "big stud" on the start relay, direct to coil + and then try to start with the key. When/ if it fires and runs, pull that loose and see if it continuses to run.
With the key in "run" the coil NEG should be very low to ground, perhaps 1/2--2V and no higher. This shows that the coil is drawing current at rest, with key "on."
TRY THIS and I'm surprised no one has said so. "Rig" an alligator clip wire between a battery source, such as the "big stud" on the start relay, direct to coil + and then try to start with the key. When/ if it fires and runs, pull that loose and see if it continuses to run.
The "start" circuit for ignition is weird. With the key in "start" there is no IGN1 "run" power. The ONLY power for the ignition system for start comes from that bypass circuit that connects battery to the coil +. BUT HOW DOES the ECU get power? It actually BACKFEEDS through the ballast "backwards" from normal, and from the ballast terminal that normally gets run power with the key in "run," it backfeeds from there to the ECU power terminal
WHAT THIS MEANS IS, that with the key in "start," the coil gets full battery voltage (even though dragged down by starter current) but the ECU only gets ?? some lower voltage from running through the ballast!!!
WHAT THIS MEANS IS, that with the key in "start," the coil gets full battery voltage (even though dragged down by starter current) but the ECU only gets ?? some lower voltage from running through the ballast!!!
standup303
Well-Known Member
I gotcha. Plugged everything back and I have 1.2v coil - to ground. I will try the 12v to coil tomorrow. Thanks
standup303
Well-Known Member
Should I pull the blue wire from the + coil before putting the constant 12v to it? Won’t it back feed the circuit if I don’t?
standup303
Well-Known Member
Landed a positive wire to + of coil straight to battery +. Car cranked and ran for 20 seconds, I removed the wire and car immediately shut off. Can’t get it to start now and not showing spark on my spark tester.
Sadly, probably just going to hire a mobile mechanic to come to the house to fix it. I’ve had about enough of this.
Sadly, probably just going to hire a mobile mechanic to come to the house to fix it. I’ve had about enough of this.
Did it shut off by itself?
standup303
Well-Known Member
hard to tell, wife said she pulled the key for some reason before I pulled the wire. Now it won’t start again.
Even with the hot wire on it?
standup303
Well-Known Member
With the hot wire on it was running. Engine shut off the second I pulled it.
Ok so it's not getting a signal on the run circuit. Shouldn't be difficult to figure out. You gotta test light?
standup303
Well-Known Member
I do yes
Start ignition switch and work your way down
standup303
Well-Known Member
Found my BATTERY red at key ignition switch almost all the way broken, 3 other wires on the fuse block almost broken, both connections loose on my anmeter. Re crimped and tightened all. I can get a steady 12.1V throughout the ignition circuit in both IGN 1 and IGN 2 EXCEPT once I land the negative from the ECU to the - on coil I drop to 10.1V. This is the same trying 2 different well grounded ECUs and 2 different coils.
Tried disconnecting the tach to see if that was it and drops to 10.1 with or without tach connected. Did same with coil tower wire to distributor, same result.
I worried about the coils after I put a straight 12v to them from battery during troubleshooting.
Does that sound like a bad coil issue to you guys?
Tried disconnecting the tach to see if that was it and drops to 10.1 with or without tach connected. Did same with coil tower wire to distributor, same result.
I worried about the coils after I put a straight 12v to them from battery during troubleshooting.
Does that sound like a bad coil issue to you guys?
Coils can be a ***** to diagnose. I normally just try another one.
standup303
Well-Known Member
I’ll grab another one tomorrow
You can actually test a coil. Unlike "internet wisdom" you CAN NOT test a coil with a multimeter. You CAN check that it's open or if it's badly shorted, you can test for a short, but there's a lot of ground in between.
So......you round up just about any "condenser" (capacitor) out of a breaker points system. Does not matter, Ford, Mopar, etc. You might want to round up two because they themselves are hard to test.
"Rig the coil up with battery and clip leads."
Hook battery + to coil +
Hook the condenser wire to coil neg
Ground the condenser can to the battery neg and do whatever is necessary to make a good connection. Alligator clip leads are good
"Rig" a METAL core (not radio suppression) wire from coil tower to a test gap and to battery NEG. If possible you want about a 3/8" gap You can use low voltage wire if you "hang it in air" so it touches nothing
Now with yet another wire connected to coil neg, tap the other end on battery neg. post. Each time you tap it, a good coil / condenser combo will make a nice hot snappy single spark.
This test WILL NOT prove that the coil is perfect as it still could have a few shorted turns and could still be somewhat degraded in performance, BUT IT SHOULD start and run.
So......you round up just about any "condenser" (capacitor) out of a breaker points system. Does not matter, Ford, Mopar, etc. You might want to round up two because they themselves are hard to test.
"Rig the coil up with battery and clip leads."
Hook battery + to coil +
Hook the condenser wire to coil neg
Ground the condenser can to the battery neg and do whatever is necessary to make a good connection. Alligator clip leads are good
"Rig" a METAL core (not radio suppression) wire from coil tower to a test gap and to battery NEG. If possible you want about a 3/8" gap You can use low voltage wire if you "hang it in air" so it touches nothing
Now with yet another wire connected to coil neg, tap the other end on battery neg. post. Each time you tap it, a good coil / condenser combo will make a nice hot snappy single spark.
This test WILL NOT prove that the coil is perfect as it still could have a few shorted turns and could still be somewhat degraded in performance, BUT IT SHOULD start and run.
I still think this is what we talked about, check the drop, with everything connected, through the bulkhead terminal, and across the ignition switch. Check with key in "run" with one meter probe on the ignition switch power infeed terminal and the other on the "run" ign1 terminal. Then make the same test with your probes at those two terminals, back probing the two terminals for the wiring.
Also at this point, you should be able to jumper power to the coil, still with everything connected, crank the engine and get spark. Alternatively, you should be able to jumper power into the junction at the key feed to the ballast, everything connected normally, and the thing should get spark.
If not, start over on the ign system trouble and yeh, I would suspect the coil.
Make sure the coil(s) you have have got matched coil/ ballast, and again, as we talked, don't leave the system powered for minutes on end
standup303
Well-Known Member
Thank you for the advice. Easiest way right now is just buying a MSD coil at Advanced Auto tomorrow morning and giving it a shot, I will definitely check compatibility with my ballast. I did use the process we spoke about and felt like I flew through troubleshooting today to find the negative on coil issue. Hoping I have a running car tomorrow.
Screw that. I'd get the cheapest POS they have that works with a ballast reaistor.......IF you are running one.
There is a range of resistance that the coil operates under that is compatible with.
Also....
The term "turn over" refers to the engine spinning with the starter in use. If the the starter is working, the engine IS turning over. If the car isn't getting spark like your seems to be, it is still turning over, it just isn't firing, getting spark, etc.
Also....
The term "turn over" refers to the engine spinning with the starter in use. If the the starter is working, the engine IS turning over. If the car isn't getting spark like your seems to be, it is still turning over, it just isn't firing, getting spark, etc.
standup303
Well-Known Member
Engine is turning over but won’t start. Got the MSD because it’s the exact one I’ve had on the car for 2 years and it is compatible with my .8 ohm resistor. Put new coil in, key on, still getting the drop to 10.2v once the negative wire from the new ECU is attached to the coil. Did tap test on ECU, works fine. Car still won’t start. I scheduled a mobile mechanic to come to the house Thursday. If he can’t get it in 3 hours I’ll have the car towed to a shop to fix it.
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