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Electrical please help! ive tried everything! no spark from coil!

  • Thread starter Thread starter conigz
  • Start date Start date May 18, 2024
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    crank but no spark
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Mcmahst

5 Year Member
Jan 19, 2021
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Laguna Woods CA, fort Mohave AZ
May 19, 2024
#21
  • May 19, 2024
  • #21
I wonder if the neutral safety switch connector is lose or has a bad/incomplete connection, removing the primary voltage to the coil. Just an idea to check.
 
P

Praetorious

Active Member
May 22, 2020
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living room.
May 20, 2024
#22
  • May 20, 2024
  • #22
That's a great suggestion, I'm of the opinion that during the tranny change something was disturbed, i know it started after that a couple of times but now it wont, something could be loose not making contact.
 
C

conigz

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May 18, 2024
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ohio
May 25, 2024
#23
  • May 25, 2024
  • #23
Mcmahst said:
I wonder if the neutral safety switch connector is lose or has a bad/incomplete connection, removing the primary voltage to the coil. Just an idea to check.
Click to expand...
It still cranks over. I've been super busy the last week. So this holiday weekend it's time to jack it up and see if anything was disturbed during the tranny install.
 

Mcmahst

5 Year Member
Jan 19, 2021
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Laguna Woods CA, fort Mohave AZ
May 25, 2024
#24
  • May 25, 2024
  • #24
Yea, I’m not sure it’s that, but those two harness connectors you had to disconnect in the previous trans effort might be the issue. These >30 year old cars can come up with interesting problems. If nothing else, you could do the clean them throughly, make sure the male pins are expanded enough to make contact, put some electrical grease on them, and retest.
 
C

conigz

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May 18, 2024
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May 25, 2024
#25
  • May 25, 2024
  • #25
I give up. I have no idea. Everything has the right voltage. Everything is connected correctly. Guess she will just be sitting for a long time. Nobody will work on her because nothing is stock and I am out of ideas.
 

rednotch

I'd like to remain having one chocolate starfish
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May 25, 2024
#26
  • May 25, 2024
  • #26
These cars don't need the ecu to create spark, you most likely have a grounding issue, or a signal wire voltage issue from the fuse link wires altering the pulse signal if the coil won't fire with the ecu in.. unplug the computer, have some one crank it while you verify spark. If you have spark check the conditions of the ecu grounds on the rocker by the computer should be 2 black wires, good idea to check the ecu relay at the same time your in there, its tucked up a bit on the harness. Also check the ecu ground that runs from the negative battery post to the fender apron by the starter selonid. This post has alot of the info you need to check it along with some pics on both pages. https://stangnet.com/mustang-forums/threads/help-no-spark-off-coil.736759/

He has more then a few videos showing how to check it, start with this one..


This video also shows the common problems on the EFI main harness, he pulls it out and goes threw it about mid way threw... Honestly at this point when I get cars with issues like this first thing I do is pull the main harness out, fix the 30yrs of abuse from multiple owners and throw in a new ecu relay and recap the ecu. Its no where near as hard as people make it out to be once the harness is out and its like 30mins to pull, take pics if your never.done it so you can remember where wires going on the selonid and and body grounds.
 

rednotch

I'd like to remain having one chocolate starfish
Founding Member
Aug 14, 2000
1,387
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south jersey
May 25, 2024
#27
  • May 25, 2024
  • #27
 
C

conigz

Member
May 18, 2024
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May 25, 2024
#28
  • May 25, 2024
  • #28
rednotch said:
These cars don't need the ecu to create spark, you most likely have a grounding issue, or a signal wire voltage issue from the fuse link wires altering the pulse signal if the coil won't fire with the ecu in.. unplug the computer, have some one crank it while you verify spark. If you have spark check the conditions of the ecu grounds on the rocker by the computer should be 2 black wires, good idea to check the ecu relay at the same time your in there, its tucked up a bit on the harness. Also check the ecu ground that runs from the negative battery post to the fender apron by the starter selonid. This post has alot of the info you need to check it along with some pics on both pages. https://stangnet.com/mustang-forums/threads/help-no-spark-off-coil.736759/

He has more then a few videos showing how to check it, start with this one..


This video also shows the common problems on the EFI main harness, he pulls it out and goes threw it about mid way threw... Honestly at this point when I get cars with issues like this first thing I do is pull the main harness out, fix the 30yrs of abuse from multiple owners and throw in a new ecu relay and recap the ecu. Its no where near as hard as people make it out to be once the harness is out and its like 30mins to pull, take pics if your never.done it so you can remember where wires going on the selonid and and body grounds.
Click to expand...
I have verified no spark with the computer out. Also I can hear the fuel pump priming with old and new computer. I have replaced everything with ignition system. Still no luck. I did go under the stang today. Everything seemed in order.
 

limp

wrap a little cheese around it and its a done
5 Year Member
Oct 4, 2020
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May 25, 2024
#29
  • May 25, 2024
  • #29
conigz said:
I give up. I have no idea. Everything has the right voltage. Everything is connected correctly. Guess she will just be sitting for a long time. Nobody will work on her because nothing is stock and I am out of ideas.
Click to expand...
Is there a member close you that might give you a hand?
What about a local Mustang or Ford club..... I bet someone in the club would give you a hand? A new pair of eyes might spot your problem quickly...
Most people I know like to help out a fellow enthusiast keeping these cars on the road?
 

rednotch

I'd like to remain having one chocolate starfish
Founding Member
Aug 14, 2000
1,387
621
143
south jersey
May 25, 2024
#30
  • May 25, 2024
  • #30
conigz said:
I have verified no spark with the computer out. Also I can hear the fuel pump priming with old and new computer. I have replaced everything with ignition system. Still no luck. I did go under the stang today. Everything seemed in order.
Click to expand...
Then you 100% have a wiring problem check the voltage on some of the 5v sensors, if any are reading low its a dead giveaway. I've bough so many cheap cars this way and its all most all ways in the main harness or injector harness when the injectors won't fire or it has no spark. Main harness is dead nuts simple to remove and go over on a work bench, injector harness just needs the upper pulled but if the injectors work I don't bother. Broken, chewed , molested wires are even fuse link corrosion is a common issue, hell the connectors are trashed on many from so many screwing with them over the years, you can buy pigtails for most.
conigz said:
Little update. But maybe a start? I unplugged the computer (which is the stock one right now.not the mega squirt, which none them worked and did the same thing.) Tried to fire it up and see if i had spark. It almost started on the left over primed fuel. I believe that both computers are good. I suck at wiring! What does that mean?
Click to expand...
Though it fired here without the computer? Wiring issues from the trans swap would generally cause a no crank issue from the neutral safety circuits so it generally won't trigger the selonid unless some one bypassed it, which isn't that uncommon on these cars now.


You said your test light goes out while cranking, do this test with a bump switch on the selonid to jump it with the key in in the key on engine off position, it cuts outs all the neutral safety wiring so make sure its out if gear. If the test light isn't flickering on the negative side its not seeing the signal and points to the main engine harness... Most likely a chaffed wiring issue in the harness which is why I suggest pulling it to repair. These kind of issues can kill tfi's and coils pretty quickly so throwing parts at it isn't the best idea.

the Tfi ignition is pretty damn simple people don't even bother changing them with carb swaps.

Dead simple way to bench test both the coil and tfi
 
C

conigz

Member
May 18, 2024
24
4
13
ohio
May 27, 2024
#31
  • May 27, 2024
  • #31
I wish. I have a couple guys who build up mustangs like myself
limp said:
Is there a member close you that might give you a hand?
What about a local Mustang or Ford club..... I bet someone in the club would give you a hand? A new pair of eyes might spot your problem quickly...
Most people I know like to help out a fellow enthusiast keeping these cars on the road?
Click to expand...
I do have a couple of guys who build up mustangs like myself. Yet..adulthood has hot us by the balls with children in sports and careers. Finding time is the hardest part. Yet you are right. A second set of eyes would be great. I'm in the country area of mid ohio. About 35 minutes north of columbus.
 
Reactions: Mcmahst and limp
C

conigz

Member
May 18, 2024
24
4
13
ohio
May 31, 2024
#32
  • May 31, 2024
  • #32
rednotch said:
Then you 100% have a wiring problem check the voltage on some of the 5v sensors, if any are reading low its a dead giveaway. I've bough so many cheap cars this way and its all most all ways in the main harness or injector harness when the injectors won't fire or it has no spark. Main harness is dead nuts simple to remove and go over on a work bench, injector harness just needs the upper pulled but if the injectors work I don't bother. Broken, chewed , molested wires are even fuse link corrosion is a common issue, hell the connectors are trashed on many from so many screwing with them over the years, you can buy pigtails for most.

Though it fired here without the computer? Wiring issues from the trans swap would generally cause a no crank issue from the neutral safety circuits so it generally won't trigger the selonid unless some one bypassed it, which isn't that uncommon on these cars now.


You said your test light goes out while cranking, do this test with a bump switch on the selonid to jump it with the key in in the key on engine off position, it cuts outs all the neutral safety wiring so make sure its out if gear. If the test light isn't flickering on the negative side its not seeing the signal and points to the main engine harness... Most likely a chaffed wiring issue in the harness which is why I suggest pulling it to repair. These kind of issues can kill tfi's and coils pretty quickly so throwing parts at it isn't the best idea.

the Tfi ignition is pretty damn simple people don't even bother changing them with carb swaps.

Dead simple way to bench test both the coil and tfi
Click to expand...
I did this test. I had spark. I pulled the codes also. Code 11/10. I have all the right voltage on everything. Like I said. Pulling my hair out!
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
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#33
  • May 31, 2024
  • #33
This is my opinion and not based on any real mechanical training but I would say if you have power at the coil with ignition switch on but no power when cranking it's between the coil and switch, fuseable link or switch. Find the wire at the switch that should be 'hot' in start, check for power out of switch
 
C

conigz

Member
May 18, 2024
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ohio
May 31, 2024
#34
  • May 31, 2024
  • #34
General karthief said:
This is my opinion and not based on any real mechanical training but I would say if you have power at the coil with ignition switch on but no power when cranking it's between the coil and switch, fuseable link or switch. Find the wire at the switch that should be 'hot' in start, check for power out of switch
Click to expand...
Speak to me as I knew nothing about electrical. Which I don't by the way. My plan this weekend was to pull the whole wiring harness and look for shorts or any irregularities. I still find it odd that 2 runs after the tremic was installed it killed. Luckily about 500 ft from my house.
 

AeroCoupe

lube between the nut and the face. I know my lubes
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#35
  • May 31, 2024
  • #35
Have you verified that the coil has 12V+ during cranking?
 
C

conigz

Member
May 18, 2024
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ohio
May 31, 2024
#36
  • May 31, 2024
  • #36
AeroCoupe said:
Have you verified that the coil has 12V+ during cranking?
Click to expand...
Yes. Test light doesn't pulse though on the negative side when cranking.
 

2Blue2

will be trying this sex one when I can find it
Mod Dude
Mar 5, 2019
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May 31, 2024
#37
  • May 31, 2024
  • #37
conigz said:
I still find it odd that 2 runs after the tremic was installed
Click to expand...
that makes ya think neutral salty switch?
 
C

conigz

Member
May 18, 2024
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Jun 1, 2024
#38
  • Jun 1, 2024
  • #38
2Blue2 said:
that makes ya think neutral salty switch?
Click to expand...
It still cranks though. I will try to bypass it today. Today is clean all grounds and pins and maybe bypass the neutral safety switch.
 
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General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
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#39
  • Jun 1, 2024
  • #39
If it's cranking over with the key, clutch pushed down, then it stops cranking when you release the clutch, with key still in crank position, then the NSS is working. I believe the NSS has nothing to do with weather or not the coil is getting power.
 
Reactions: 2Blue2
C

conigz

Member
May 18, 2024
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ohio
Jun 1, 2024
#40
  • Jun 1, 2024
  • #40
General karthief said:
If it's cranking over with the key, clutch pushed down, then it stops cranking when you release the clutch, with key still in crank position, then the NSS is working. I believe the NSS has nothing to do with weather or not the coil is getting power.
Click to expand...
Thanks. Coil is getting power. Just not sparking.
 
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