no spark...I think? ...Anyone live in Frederick? (1 Viewer)

[DustyFJ]

Any progress on this?

Taking care of family stuff, haven't been home. I ordered a new coil, I'm thinking that will fix it...If not...then I dunno...

 

[DustyFJ]

Do you have an Ohm meter? If so, what is the resistance (Ohms) between the "+" and "-" terminals on the coil and between the "-" terminal and the high voltage output terminal on the coil?

If you don't have a meter, the $15 to buy one is a good investment.

Let me know what you find.

I'll have to check and report back. I've got a fluke 87 in the garage.

 

[rkymtnflyfisher]

That Fluke will do exactly what you need it to.

 

[emorth]

DustyFJ,
Did you see this thread? https://forum.ih8mud.com/threads/ignition-101.871796/
Fluke 87, nice!

 

[DustyFJ]

DustyFJ,
Did you see this thread? https://forum.ih8mud.com/threads/ignition-101.871796/
Fluke 87, nice!

I did today yes, helpful. Thank you. Though I'm not clear exactly on why the first "new" coil went bad after only six months of use. It is supposed to be internally resisted. The second coil(old one that came with the truck) says right on it that it requires an external resistor so it makes sense that it could have gone bad after ten minutes or so I guess.

and the fact that swapping coils made it run makes me think, yes the coil is bad. tomorrow after work I will pull the one on there and compare/share ohm readings.

 

[DustyFJ]

Do you have an Ohm meter? If so, what is the resistance (Ohms) between the "+" and "-" terminals on the coil and between the "-" terminal and the high voltage output terminal on the coil?

If you don't have a meter, the $15 to buy one is a good investment.

Let me know what you find.

first coil that went bad:

post to post 3.6 Ohms
Post to center 10.9K Ohms (same from both posts)

second coil, says internally resisted on it

post to post 1.7 Ohms
post to center 11.2K Ohms (same from both posts)

 

[emorth]

Interesting numbers. The measurements for the second ignition coil look right (1.7 & 11.2k Ohms). The 3.6 Ohms for the primary winding of the first ignition coil seems high - approx twice the resistance of the second ignition coil. Not sure how a failure could just slightly increase the resistance. Typically, the failure mode in the primary winding is an open (infinite resistance) circuit because it burned out. Is there any possibility that this coil came from an engine/vehicle with a 24 volt electrical system? That would explain twice the resistance for the primary coil.

One thing to consider, the resistance measurement of the secondary winding (11k Ohms) is at low (Ohm meter battery) voltage. It is possible that the insulation on the secondary winding breaks down at high voltage which allows the spark to fire within the coil so it never leaves the ignition coil.

The good news is, nothing caused the primary winding to burn out on the first (original) ignition coil. Hook up the new coil and see what happens. Insert a spark tester (light) between the coil and distributor so you have a visual indication when the spark occurs.

Please let me know what happens.
Ed

 

[emorth]

One more detail... the difference between the secondary winding resistances (10.9k & 11.2k Ohms) is insignificant.

 

[Stumpalama]

Again with the knowledge bomb!

 

[rkymtnflyfisher]

Prime opportunity to play with the megger.

 

[OTRAMM]

I've got a megger I've yet to get to play with.

 

[DustyFJ]

Installed the new coil...nothing...

Went through checking everything again found once again I had 12v on both sides of the coil but only one side of the pick-up inside the distributor. Found a second bad factory crimp connection inside the distributor. Cussed a bit for not finding it sooner but it was good earlier, it went bad during the troubleshooting process. Crimp LOOKED good but crimped too tight and the wire was broken inside the insulation. New spade connector and the truck fired right up. Too many vehicles to move to take it for a drive but soon...

Thanks for the help Ed and everyone. It was a good learning experience. Frustrating, and I spent 80 bucks I didn't need to but at least now I know how the ignition system works.

 

[Devilmans Hand]

Just think of those extra parts as spares.

 

[rkymtnflyfisher]

I've got a megger I've yet to get to play with.

Nothing like catching one of your buddies snoozing and hitting them with 1000v!

 

[emorth]

Happy Motoring!!!