351M. Took the heads off to replace the gaskets. Put everything back together now no spark. Put a screwdriver in the wire from the coil and put it next to ground and no spark. Put a regular electrical wire in the coil opening and the other end near the block ground and no spark. Checked the coil for voltage, getting 12 at the POS termingal on the coil. checked the values on the coil - terminal to terminal getting 1.3 ohms, coil to terminal getting 7.1K ohms. I really don't think the coil is the problem but it seems a little off the standard of .75 and 11K.
Replaced the control module on the drivers side fender, (79 Bronco) also replaced the electonic contoler on the passenger fender. Checked the relay points which have one terminal going to the battery, the opposite side to the starter motor and in between two posts one labeled S and the other I. The S is obviosly the POS from the interior key switch and that works, the one labeled I is showing 12V with key in run position. The connector from the firewall/ key swith shows 12V from both leads. I am out of ideas. I thought maybe ensuring the coil is grounded by placing a wire from the NEG post on the coil to ground but was not sure if that would damage anything. Anyone have any ideas? I could use the values at certain points to test. Thank you. Ed Johnson. 443-789-6207

 

The negative side of the coil does not get grounded. It gets a signal from the "points" which in your case is the reluctor in the distributor. You need to see if you are getting a signal to that point. Without a scope I don't know how to really check that. I would think that an analog DC voltmeter might work if you connected it and watched for a needle swing as someone turns it over.

My problem with this is thinking of a way to troubleshoot without an ignition scope close at hand. How about trying this: with 12 Volts on the positive side of the coil and the lead that goes to the distributor center set up about an 1/8" from a good ground, use a jumper wire on the coil negative. Strike it a few times and see if you get a spark. If you don't get a spark the coil is probably bad. If you DO get a spark then check out the distributor. The problem could be the small module that takes the place of the points.

Find a procedure to check it though, don't just throw money at it by buying and replacing parts as an experiment.

Good luck,

 

Would it be logical for me to purchase a scope for this issue and future issues or are they rather expensive? Weird thing is it worked, replaced head gaskets and not it does not makes me feel like a wire is open or shorted. Can you suggest testing voltage points? Like make sure your getting 12V at the Coil etc. I disconnected the batt when doing the work so I can't imagine something working yesterday and not work today under these circumstances. Is there an in-line fuse somewhere? Any way to test the lines to the electronic module? I had my oil pressure gauge hose burst under my dash about a month ago. Perhaps the oil under the dash around the wires worked its way into something causing a short that is only now showing up? Thank you. Ed.

 

the pickup in the distributor puts out about .5 vac if you have a wveform viewer or scope you can see a graph of volts & time, but its just an ac voltage generator so if you see about .5vac from dist pickup, it should be ok. The module is a more likely candidate

 

Make sure everything is plugged in and the contacts inside the connectors aren't corroded. If they are spray a little wd-40 in them and use some fine sandpaper. The grease will hold onto the crap and allow you to rinse it out with more wd-40. You might want to make sure you have good wires. If you put a test light in the NEG side of the coil and ground it it should flash when the coil fires.

 

Alright, I tried another coil and electronic module, no luck. I need test points to determine where the problem is. Positive on the red wire to the coil etc if anyone has those facts, thanks. Otherwise I am going to the local ford dealer, flashing a hundred bucks and telling the widest eyes to come to my house and fix my issue and the 100 is yours. Someone who knows exactly what to look for at certain points should be able to isolate the problem in about 15 minutes.