1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Coil Sparks, but no spark at the plugs

  #31  
Old 04-23-2016, 10:10 PM
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have you done a compress check?
 
  #32  
Old 04-24-2016, 09:43 AM
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Thank you for the links; very informative. I have not done a compression test (although I have a record from the previous owner and it looks pretty consistent).

Keeping Occam's Razor theory in mind, I wonder if my new distributor cap could have a spot where spark is being lost or is it possible for the plastic bottom of the distributor to be a spot to lose spark intensity? Is ignition timing a possibility? I will double check that & compression test.
To clarify: when I said it would fire on ether, that was as long as it was being engaged with the starter.
 
  #33  
Old 04-24-2016, 11:06 AM
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Originally Posted by Telestar
Thank you for the links; very informative. I have not done a compression test (although I have a record from the previous owner and it looks pretty consistent).

Keeping Occam's Razor theory in mind, I wonder if my new distributor cap could have a spot where spark is being lost or is it possible for the plastic bottom of the distributor to be a spot to lose spark intensity? Is ignition timing a possibility? I will double check that & compression test.
To clarify: when I said it would fire on ether, that was as long as it was being engaged with the starter.
If you are unplugging the coil wire at the dist cap and a connecting the spark tester you are testing before the dist.
 
  #34  
Old 04-24-2016, 12:45 PM
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Agreed

Originally Posted by JimsRebel
If you are unplugging the coil wire at the dist cap and a connecting the spark tester you are testing before the dist.
Testing that way omits the distributor from the equation.
 
  #35  
Old 04-27-2016, 07:08 PM
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Originally Posted by JimsRebel
Very good question, DS2 will jump a .045-050 gap ... but not a .070 gap.

It cant start on ether if there is not a spark jumping the gap on the plugs.

I would gap the plugs at .030, OK I do know that is a small gap , like what is used on a old point set up, but I am running out of ideas here.
If it make you feel better my airplane engine has the plugs gaped at .015-.019 .. and it wont start much past that gap.
All that is left is dwell issues which should be taken care of buy the DS2 IGN module.
In proper dwell causes a weak spark.
How to Make Sparks
Coil Dwell, I don't think its right causing weak spark. - evolutionm.net

Jim
I gapped the plugs at .020 per Taylor coil recommendations... no start. I am thinking there is too much resistance on the coil tower connection of the distributor cap (brand new BWD brass coated or brass towers) testing the coil tower shows at least 100 ohms, spark plug towers show close to zero. What is acceptable resistance on the coil towers?
 
  #36  
Old 04-28-2016, 11:41 AM
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So, last night after dark I went out and tested for spark; I have good blue spark coming front the coil and an intermittent spark from the plug wire. Also, while testing, my bare arm was resting against the hood latch & I could feel a slight shock while cranking.
 
  #37  
Old 04-28-2016, 01:38 PM
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Originally Posted by Telestar
So, last night after dark I went out and tested for spark; I have good blue spark coming front the coil and an intermittent spark from the plug wire. Also, while testing, my bare arm was resting against the hood latch & I could feel a slight shock while cranking.
Lots of back and forth in this thread, so forgive me if this has already been suggested, but have you tried a new distributor cap and rotor? If yes, have you tried new plug wires? Per the current symptoms, those things are pretty much your only possible culprits.

If reluctant to spring for new, do you have the old pre-trouble parts? If already new, consider trying a different brand. I've had plenty of new parts bad from stock, so don't automatically rule out that possibility.
 
  #38  
Old 04-28-2016, 04:51 PM
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Originally Posted by kr98664
Lots of back and forth in this thread, so forgive me if this has already been suggested, but have you tried a new distributor cap and rotor? If yes, have you tried new plug wires? Per the current symptoms, those things are pretty much your only possible culprits.

If reluctant to spring for new, do you have the old pre-trouble parts? If already new, consider trying a different brand. I've had plenty of new parts bad from stock, so don't automatically rule out that possibility.
Yes, new cap, rotor & wires; I still have the old parts too. I am thinking the new cap may be bad as well, thank you for you help.
 
  #39  
Old 04-28-2016, 06:11 PM
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I would second the notion of putting the old parts back, one part at a time and see if any specific component is causing the problem.
 
  #40  
Old 04-28-2016, 06:17 PM
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Originally Posted by Telestar
Yes, new cap, rotor & wires; I still have the old parts too. I am thinking the new cap may be bad as well, thank you for you help.
Are the old parts pre- or post-trouble? The reason I ask is that you want to install a known good part (pre-trouble) if at all possible.

As far as new parts bad from stock, I went through a lot of grief with a new cap and rotor many years ago on a different vehicle. After installing a whole boat load of new parts while tackling some major repairs, the engine ran much worse than before. I reached a lot of dead ends before realizing some of the new parts were probably bad.

Unfortunately, I went back to the same store without really thinking, and got MORE bad parts from the same defective batch. Talk about a headscratcher! I was tearing my hair out trying to figure it out, as everything still pointed to a bad cap or rotor. Out of desperation, I tried another bring from another store and then the engine once again purred like a kitten. This is why I recommend changing one part (or making one adjustment) at a time whenever possible, instead of a whole bunch of things at once.

Just something to consider. YMMV.
 
  #41  
Old 04-29-2016, 06:48 PM
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Originally Posted by kr98664
Are the old parts pre- or post-trouble? The reason I ask is that you want to install a known good part (pre-trouble) if at all possible.

As far as new parts bad from stock, I went through a lot of grief with a new cap and rotor many years ago on a different vehicle. After installing a whole boat load of new parts while tackling some major repairs, the engine ran much worse than before. I reached a lot of dead ends before realizing some of the new parts were probably bad.

Unfortunately, I went back to the same store without really thinking, and got MORE bad parts from the same defective batch. Talk about a headscratcher! I was tearing my hair out trying to figure it out, as everything still pointed to a bad cap or rotor. Out of desperation, I tried another bring from another store and then the engine once again purred like a kitten. This is why I recommend changing one part (or making one adjustment) at a time whenever possible, instead of a whole bunch of things at once.

Just something to consider. YMMV.
I have tried these parts, some still test bad. I think there are (were) multiple problems. I did recheck the timing and found that the distributor was off one tooth, it sounded like it wanted to start. I was encouraged by that & will attempt to start when I get a chance. After seeing the intermittent spark from the plug wire in the dark; I started thinking about the timing; I could not see the spark in the daylight with the HEI tester. My thinking is: maybe the timing being off one tooth could create an intermittent spark & a no-start condition... I could be all wrong, but it sounded like it was trying to start, maybe a little ether & fine tuning the timing will do it?
 
  #42  
Old 04-29-2016, 10:19 PM
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Originally Posted by Telestar
I have tried these parts, some still test bad.
I'm confused here. Are you saying some parts (which ones?) have tested bad but are still currently installed? That doesn't make sense but that's how I'm reading your statement.
 
  #43  
Old 04-30-2016, 09:06 AM
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Originally Posted by kr98664
I'm confused here. Are you saying some parts (which ones?) have tested bad but are still currently installed? That doesn't make sense but that's how I'm reading your statement.
The old cap, rotor, coil, ICM & ballast resistor which are currently not installed.
 
  #44  
Old 05-03-2016, 02:54 PM
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Originally Posted by JimsRebel
The next step will be to run 12 volts directly from the battery to BOTH the coil positive and the red wire on the DS2 IGN module.
This will eliminate all truck wiring. It will / should start with your remote starter.
Full voltage at the coil will help deliver a hotter spark. Check this at the coil wire, spark tester to ground.

Jim
I readjusted the timing to a base 10 degrees and tried to start with the remote starter & ether... would not fire. I then hooked up the jumper wire from the battery to the ICM and tried it with ether and it fired up, it would stay running as long as I sprayed ether. I checked and it's not getting fuel. I replaced both in tank pumps awhile back. One tank is full of old gas, the other is empty. I am just wondering about this weird fuel system; do you have to use the ignition switch to prime the pump or should it work with the remote starter?
I will get some gas for the other tank in a day or two when we go to town.
 
  #45  
Old 05-04-2016, 02:23 AM
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Well done!

The fuel pump should only run with the key on.

Do you have power to the ICM with the key on? If you don't then you have to wonder about the key and ignition switches, and fuses.
 

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