Dead coil

[nick_vw]

Ok so after getting an intermittent no spark situation, I pulled all leads off the coil, put +12v to to (+) post and attached a spark plug to the firing lead and grounded it well. Then i momentarily grounded the coil with a jumper on the (-) post and i got NO spark on the plug, although the jumper lead sparked when touching the coil post. Can anyone confirm the plug SHOULD fire by momentarily grounding the coil?

This brings me to my next question, I believe I have a bad resistor wire. Because its about 1 coil per season that i have replaced. Can I get a coil with built in resistor, and just run a new lead from the alternator and starter (non resistive leads)?

thanks for the help.

 

[Howard Sterndrive]

Re: Dead coil

it should fire when you REMOVE the ground, not when you apply it.

and yes, you can eliminate the resistor and get a coil designed to run with full 12V + to the + terminal

 

[nick_vw]

Re: Dead coil

ok, got myself a mercruiser replacement (sierra coil) with built in resistor. Realized its a bit of work to route a new wire from the alternator so i just zip tied it to the back. Weird thing is it didn't work right away, I took the distributor cap off and opened/closed the points a few times manually and it made contact. must have been some corrosion.

bad resistor wire is the only logical reason i can see my coil breaking down every year, Its in a good spot as far as heat goes. I wanted to hook up my tachometer, and i can see there are 3 wires on the (-) side of the coil. one for the distributor, the other into a plug with 2 pins (assume this is shift assist/safety switch) the other into the big connector. both are a blue color with a faded stripe, not gray. Is it a safe bet that the wire running into the main connector that runs up front is the tach wire?

 

[astuckey]

Re: Dead coil

How much resistance does the coil have? You can burn up your points pretty quick if you don't have enough resistance.

 

[bradb]

Re: Dead coil

How old are your points and do you have the dwell set properly? You set then with a dwell meter...no just gap with a feeler gauge.

 

[Bondo]

Re: Dead coil

ok, got myself a mercruiser replacement (sierra coil) with built in resistor. Realized its a bit of work to route a new wire from the alternator so i just zip tied it to the back. Weird thing is it didn't work right away, I took the distributor cap off and opened/closed the points a few times manually and it made contact. must have been some corrosion.

bad resistor wire is the only logical reason i can see my coil breaking down every year, Its in a good spot as far as heat goes. I wanted to hook up my tachometer, and i can see there are 3 wires on the (-) side of the coil. one for the distributor, the other into a plug with 2 pins (assume this is shift assist/safety switch) the other into the big connector. both are a blue color with a faded stripe, not gray. Is it a safe bet that the wire running into the main connector that runs up front is the tach wire?

Ayuh,... The Points, not the coil is the Problem,....

 

[nick_vw]

Re: Dead coil

Ayuh,... The Points, not the coil is the Problem,....

Actually it was both, the old coil is dead (cant make even a little spark) but the new coil sparks bright blue. things just seem to have broken down over the winter :cold: