1977 F-150 351M no spark

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Old 09-09-2017, 07:56 AM
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1977 F-150 351M no spark

Ok, engine cranks over fine, poured gas in carb, but it isn't firing. Checked and we have power to the coil connector, but when we pull the wire on the coil off the distributor cap to check for spark, nothing. Opened distributor cap to see if rotor is spinning, and it is. What or how to I check for spark from the coil to distributor, etc? Is the electronic box on the drivers side for the spark? Sorry, i'm not very good at this stuff. Bad coil, or bad ignition module box? I bought the truck from a guy who said it was parked because his Dad couldn't drive anymore. He claimed it did run, but that has been a few years ago (nine years, I believe). I'm thinking it must be either the coil or the ign module box. I don't know what else it could be since i have power to the horseshoe connector. Any advice would be appreciated.
 
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Old 09-09-2017, 08:24 AM
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I have been reading up on the ICM's for 1977 and early 1978 and understanding they were not very good. Could I go to like O'reilly's and get an ICm and just change it out? I understand they are fairly cheap, anyway.
 
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Old 09-09-2017, 12:01 PM
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If they're really cheap, it's definitely worth trying. If you can get a cheap coil, try that as well.

I'm not familiar with engines of that vintage. Does it have points in the distributor? A condenser for the points? Those should be really cheap, so check those out as well if you have them.
 
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Old 09-10-2017, 01:49 AM
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Got her fixed within one hour. I had power at the coil wiring c clip, but nothing coming out of the coil. I put a coil in it, and still no spark. Switched out the ICM and it fired right away. Fifty eight bucks later, I'm back in business. I didn't figure it should have been too big of an issue, just new to the old ford trucks.
 
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Old 09-10-2017, 04:21 PM
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Originally Posted by xlt4wd90
If they're really cheap, it's definitely worth trying. If you can get a cheap coil, try that as well.

I'm not familiar with engines of that vintage. Does it have points in the distributor? A condenser for the points? Those should be really cheap, so check those out as well if you have them.
77 had Duraspark .
 
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Old 09-10-2017, 06:29 PM
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Originally Posted by baddad457
77 had Duraspark .
Thanks, and I'm reading that it's a common upgrade for ignitions in old cars. Time to check the junk yards for something I can install into my 69 Mustang.
 
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Old 09-10-2017, 08:42 PM
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Originally Posted by xlt4wd90
Thanks, and I'm reading that it's a common upgrade for ignitions in old cars. Time to check the junk yards for something I can install into my 69 Mustang.
It's a good low buck upgrade. Only Improvement I made to my 77 Comet was converting to a large dist. cap, Ford Racing 9 mm wires and a hotter coil. Doesn't miss a beat up to 7000 rpms in my 331. I'm using a stock reman 85 Stang distributor as is, right out of the box.
 
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