f250 coil problem
Postmaster
Joined: Feb 2011
Posts: 3,560
Likes: 1
i assume your talking ignition coils? maybe he's buying cheap parts, like the parts store's house-brand - i know oreilly's house brand, masterpro, is better called masters**t because their quality is horrible.
if its not that, lets get into a little more detail here - what year, engine, and ignition system? has he done any kind of customizing to the ignition system?
if its not that, lets get into a little more detail here - what year, engine, and ignition system? has he done any kind of customizing to the ignition system?
Postmaster
Joined: Feb 2011
Posts: 3,560
Likes: 1
what year is it - is that a TFI system or a duraspark? a duraspark system has a resistor that reduces voltage to the coil, and it it somehow got bypassed, or if the module has wires crossed or shorted and thinks its starting the engine, it sends a full 12v to the coil.
and what brand of coil are you using?
either you're buying junk coils, or you're dealing with a strange wiring problem
and what brand of coil are you using?
either you're buying junk coils, or you're dealing with a strange wiring problem
Posting Guru
Joined: Aug 2009
Posts: 2,271
Likes: 2
From: Mexia, TX
what year is it - is that a TFI system or a duraspark? a duraspark system has a resistor that reduces voltage to the coil, and it it somehow got bypassed, or if the module has wires crossed or shorted and thinks its starting the engine, it sends a full 12v to the coil.
Fleet Mechanic
Joined: Oct 2010
Posts: 1,690
Likes: 32
From: Delhi, Iowa
Not to hijack the thread, but in the discussion of coils, im looking at running a slightly hotter coil on my truck ( 81 F150, 300 six, duraspark ignition) and was thinking of running an Accel coil. Any thoughts?
Postmaster
Joined: Feb 2011
Posts: 3,560
Likes: 1
12V won't hurt the factory coil. I run an MSD 6A ignition module which puts out quite a bit more juice than the Duraspark system, and the factory Motorcraft coil worked fine with it. Never had any issues at all, even when I moved up to a .050" plug gap instead of the stock .046".
so if my guess doesn't work, what do you think COULD be killing his coil?
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Postmaster
Joined: Oct 2008
Posts: 3,026
Likes: 0
From: Renton, WA
OP a bad coil or plug wire, cap, etc could be letting the high voltage side jump to the low voltage side damaging the coil.
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Senior User
Joined: Jul 2007
Posts: 287
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From: Ohio
Well his truck is a 1980 and it is a dura spark. Also he said he use to have to change the coil about once a year. Now when he changes it he can drive for awhile and then it dies after about 15 mins it will fire back up. Then get 2 miles down The road and it dies again also its a coil from AutoZone.
Posting Guru
Joined: Apr 2011
Posts: 1,636
Likes: 5
From: Orlando area
Well his truck is a 1980 and it is a dura spark. Also he said he use to have to change the coil about once a year. Now when he changes it he can drive for awhile and then it dies after about 15 mins it will fire back up. Then get 2 miles down The road and it dies again also its a coil from AutoZone.
Moderator
Joined: Jan 2001
Posts: 56,990
Likes: 2,740
From: Virginia
12v on the coil can ruin it. It depends on the ignition system. On the old points systems and the duraspark system, they rely on the resistor to control the current through the coil and the points or ignition box. On the GM HEI and Ford TFI, they have a circuit internal to the module that controls the current through the coil.
I am not sure about the MSD and how it works, but I would assume they also have circuitry inside their box that controls the current through the coil and keeps it from overheating.
As far as the hotter coil on the duraspark II system;
You don't get something for nothing. A hotter coil means more load on the ignition box. Some people run hotter coils on their duraspark systems and have no problems. But it's just putting more strain on the system, and I do not like flirting with disaster. If you want to experiment with it, go ahead.
I am not sure about the MSD and how it works, but I would assume they also have circuitry inside their box that controls the current through the coil and keeps it from overheating.
As far as the hotter coil on the duraspark II system;
You don't get something for nothing. A hotter coil means more load on the ignition box. Some people run hotter coils on their duraspark systems and have no problems. But it's just putting more strain on the system, and I do not like flirting with disaster. If you want to experiment with it, go ahead.
Junior User
Joined: Nov 2012
Posts: 64
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From: ok
im thinking the hall type pickup in the distributor or the ignition control module. a quick way to tell is to manually fire the coil by energizing and collapsing the field while holding the coil secondary close to ground. id also want to see if the ign module hot wires are taped to one source as happens often in older machines. another place to look is the actual coil type. the only time they generally die that fast is if you use a point type coil with electronic ignition. just a few quick places to start hunting.
FTE Chapter Leader
Joined: May 2002
Posts: 42,641
Likes: 3,146
From: Fraziers Bottom, WV
The question I have is: Has the DS II module been replaced? If so there are 2 different units. 1976 module (if i remember right is a white connector at the module) and 77 and later with a blue connector. They are wired different between the two.
Next thing is, In all my years of vehicle repair working around a shop I have never had several coils go out on one vehicle and it be the coils. It is always something else that caused repeated failures.
Here is a link to AutoZone's DIY repair guide and it has a very good description on the system and testing. | Repair Guides | Dura Spark Electronic Ignition Systems | All Carbureted Engines | AutoZone.com
Rod
Next thing is, In all my years of vehicle repair working around a shop I have never had several coils go out on one vehicle and it be the coils. It is always something else that caused repeated failures.
Here is a link to AutoZone's DIY repair guide and it has a very good description on the system and testing. | Repair Guides | Dura Spark Electronic Ignition Systems | All Carbureted Engines | AutoZone.com
Rod
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 39
From: EXTREME southwest CT
I would say that if it IS the coil... and it doesn't seem that multiple coils are faulty... then either the resistor wire in the harness has been bypassed -or- he is leaving it with the ignition in the 'run' position, instead of 'ACC' for prolonged periods.
Listening to the radio for a couple of hours is a surefire way to overheat a coil.
Listening to the radio for a couple of hours is a surefire way to overheat a coil.
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