Distributor cap fouling

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May 14, 2013 | 11:13 PM

#16

FordFanboy

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Quote:

Originally Posted by fmc400

I'm not one to recommend people replace parts unless there's a compelling reason to do so, but in this case a coil is cheap enough that you could pick a new one up to eliminate all doubt.

Yeah, I'm the same way. Of course there are 3 or 4 parts that I could say the same thing about. Always good to have a spare, too.

Quote:

Originally Posted by fmc400

Sorry if I missed this, but when the truck won't start, have you checked for spark?

No, that's the obvious next step. Unfortunately each time it has happened, I have been stuck on the side of the road with somewhere to be in a hurry. I'm trying to recreate it now, but I don't won't to drive too far from home. I may end up driving around the block 100 times.

When it does happen, I want to be prepared with some tests to narrow down the problem. So...

Check for spark. Spark good, not electrical. No spark...
Take ICM to Autozone
??

Is there a way to check the coil or coil pick-up when it goes down? Anything else to look at? Is there a way to check the ICM myself?

May 14, 2013 | 11:32 PM

#17

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

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From: Austin, TX

You can measure the resistance of the primary and secondary windings of the coil. You can check the function of the ignition module (and the distributor pickup) by connecting a test light between the negative (TACH TEST) terminal of the coil and clean, unpainted metal on the engine (ground). When you crank the engine over with the key, the light should BLINK. If this doesn't happen, you won't even have spark.

Sounds like checking for spark during the failed state needs to be top priority, since a lot of what-if's ride on that.

May 22, 2013 | 11:39 PM

#18

FordFanboy

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Alright, I think I have it narrowed down.

I think the reluctor is contacting the coil pickup (#9 on this diagram) and causing all the fouling inside the distributor cap. I'm going to get a new pickup; however, my truck is missing the wire connector for this part. The old one is just spliced into the wires. So, would you recommend I:
a - cut the connector off the new part and solder splice the wires
b - try to find the right connector and splice it in (anybody have a source for the connector by itself?)
c - fabricate some sort of homemade connector
d - something else

Also, I think I have a bad connection in the coil socket (#11 on the above diagram). This seems like it would be a common problem. Is there a home remedy for this issue or should I just get a new one?

May 23, 2013 | 07:21 PM

#19

MeanGreen460

Elder User

Joined: Mar 2013

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From: In Hastings Delton area

I'd replace the cap and rotor with good ones with brass contacts and a little dielectric grease .Check for spark you may have a bad ignition module also that blue cap vacuum port on left front of carb is where your vacuum should be hooked to your distributor .

May 23, 2013 | 08:17 PM

#20

Blue and White

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Joined: Nov 2011

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Quote:

Originally Posted by FordFanboy

It sounds like the distributor has had a rough life. All that dust couldn't help the advance mechanism. I would personally swap it for a reman that should be cleaned up and tested. For the coil connections, crimp and solder a ring terminal, nut and lock washer works fine. Just label the wires. On the reluctor connection, I'd look for the matching terminal. Solder would work but it really needs to be serviceable. One option would be to cut one off a jy harness and splice to your engine harness.

May 30, 2013 | 09:32 AM

#21

FordFanboy

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Just to close out this thread:

I believe that the fouling was caused by the reluctor contacting the magnet in the coil pickup and grinding off material. I have replaced the whole distributor and will be monitoring the cap to see if the fouling comes back.

I also got the coil pickup wire connector from an 80s Bronco at the junk yard and soldered it into place, so now I have an easy connection there. I got the coil wire bracket as well, but I tightened up the contacts on my existing bracket and that seems to be nice and snug now.

I have been driving around some with no problems so far. Thanks for everyone's help.