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A troubleshooting tip for those with Duraspark ignition
Just a little fyi I thought I would pass along. My 79 F100 302 with Duraspark ignition suddenly died on the way home the other day. I took the air cleaner lid off to determine if it was air/fuel or ignition related. Since the air cleaner was off and not an issue and I could see a shot of fuel enter the carb when I worked the linkage by hand, I knew it was a "no spark" situation.
I tried cranking it again and noticed it would try to fire as I released the ignition switch. (I remembered these same symptoms about two years ago when I had to replace the pick up coil in the distributor.) It finally started then died again. I did manage to get it started and drive it home but it died two more times before I got it there.
I pulled off the distributor cap and sure enough as I suspected the wire was broke off inside the distributor right as it enters the pickup coil. The exact same thing happened two years ago and had to get it towed home. The wire was just hanging on by a thread and would intermittenly make contact.
The funny thing about this is, when I rebuilt the engine back in 1998, I replaced the original pickup coil with a new one just because it was old and had 174000 miles on it. The wire broke off the replacement 102000 miles later and this one broke off after 28000 miles.
Just a little tip for ya to keep in the back of your mind if you encounter similar situation.
Make sure you have plenty of slack in this wire. The pickup is mounted on a plate inside the dist that moves with the vacuum advance and the centrifugal weights inside, that's how it advances and retards the timing. So this wire is flexing continually, and is usually a special type wire like meter lead wire. Knowing the way parts are made now, they may be using inferior type wire, and like I said, make sure there is slack enough for the wire to move with the plate.
Thanks for the tip. There appeared to plenty of slack, yet they both broke off right at the magnet. I'm thinking, as you mentioned, the cause is inferior wire. The insulation of the wire in that area is hard an brittle. Probably some cheap stuff not rated for engine heat and/or movement. I saved all the ones I've replaced including the original one that came on the truck. You can clearly see the original is made from much thicker wire and is not brittle. If it weren't for the broken plastic connector outside of the distributor, I'd put the 174000 mile original back on.
Here's an update. I got a brand new replacement pick up coil from NAPA and installed it Friday night, still no spark. I just about pulled my hair out today troubleshooting this thing. I checked voltage to the coil, ohmed out the coil, swapped the module for the one I carry behind the seat, still nothing. I decided to ohm out the new pick up coil which is supposed to be between 400-1000 ohms. The ohm meter showed it was open. I immediately put the original 33 year old 174000 mile original pick up coil back on the truck and she fired right up.
This is a sad day in America considering all the technological advances we have made in the past 33 years, when a well used, high mileage part is better quality than what you can buy new today.
The quality of new parts is a major problem with some guys who like to use the "shotgun" approach. Some people have a problem, and instead of troubleshooting and keeping track of the symptoms, they just replace everything expecting it to be fixed since everything is "new". That's when they find out they have more problems than when they started with. See it all the time now.
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