OK - I seem to have been working on the problem for weeks and can't solve it.

I have a 2.0 Pinto with Electronic Ignition (Make Unknown)

When I crank the engine I have a spark at the end of the HT Lead coming out of the Coil.

I then connect it to the distributor but the spark disappears and I get no spark at any of the plugs.

I have changed the Dizzy Cap, Rotor Arm, Plug Leads and still no change

Haven't got a clue what to do next but I won't be beaten!

Has anybody any ideas what could be causing this as I haven't come across this before.

Many Thanks for any advice!

Stephen

Edited May 6, 20251 yr by Worcester19

Coil breaking down?

Is the carbon brush in the centre of the distributor actually touching the rotor arm?

I’ve measured it and it looks like the carbon brush is touching the Rotor.

id not considered the Coil before as I knew it was pushing out a spark - but I need to check if it’s strong enough.

 For the ideas 

I checked the coil tonight with a Multimeter and all is good.

back to the head scratching!!

When you say you get a spark out of the king lead is this lead to engine block or have you put a spark plug in the end of the king lead and touched the plug body to the block?

The latter requires a higher voltage to create a spark and this is what the engine sees.

 

Hi , I had a similar problem 3 years ago If you dizzy connects with a plug from the wiring harness on the dizzy check it for corrosion mine did the same thing  I replaced the plug in the dizzy and the harness hey presto all good. just something else to check.👍

Thanks for the replies,

i’m going to start from scratch and check all connections tomorrow.

 

started to wonder if the coil is receiving enough voltage as there is a difference between holding the king lead against the body and holding the king lead with a spark plug against body as suggested.

still welcome peoples thoughts though!!

 

 

Coils can gradually die.

They are essentially transformers and work on change in electrical currant.

They have a few turns of wire between the + and - connections this is the primary of the transformer and a lot 10000+ more turns of finer wire as the secondary. The secondary and primary share a common connection the other secondary connection is the top of the coil where several thousand volts appears.

The wires ( primary and secondary ) are solid copper insulated with varnish. The secondary has to be wound carefully to prevent overloading the varnish insulation.

The current in the primary builds slowly because it is creating a magnetic field. The current in the primary is stopped causing  a large voltage in the secondary and a spark in the plug as the magnetic field collapses.

Creating the magnetic field also puts a force on the wires (magnets attract or repel) this tries to move the wires so that the rub against each other removing some of the varnish insulation. Sparks (or worse shorts) appear taking the energy intended for the spark and generating heat in the coil. The assembly should be impregnated with insulating material (like epoxy) to prevent this but bubbles can be left allowing a gradual degeneration of the insulation in the bubbles. This has little effect on the DC measured resistance of the coil but measuring the inductance will show it up. Unfortunately few electrical multi meters measure inductance.

The best test is to substitute a known good coil, sorry if I have been too wordy.

Edited May 9, 20251 yr by IanS
spelling

A coil is definitely a good suggestion.

Thanks guys - really appreciate the help responses.

had an old coil hanging round the garage so fitted that and now get a larger spark out of the HT lead but only a small spark at the plug.

The cars coughed a few times but don’t think there is enough to make it start.

ordering a new coil and let’s see what happens 

thanks again

 

 

One step forward keep on going and you will get there🙂

1 hour ago, Worcester19 said:

Thanks guys - really appreciate the help responses.

had an old coil hanging round the garage so fitted that and now get a larger spark out of the HT lead but only a small spark at the plug.

The cars coughed a few times but don’t think there is enough to make it start.

ordering a new coil and let’s see what happens 

thanks again

 

 

Sorry if I missed this but you have changed the leads?

Hi - yes have changed the leads, dizzy cap, rotor arm, checked for good earth, have replaced the coil.

could it be that the amplifier is failing. Was going to take the dizzy into a repair shop to get it checked but still grateful for any ideas

 

thanks!!

Bearing in mind it's a while since I worked with anything that had a 'basic' ignition firing system virtually everything I've worked on in the last 20 years has been electronic.

But how about going back to basics, turn the engine until your rotor arm is pointing towards one of the leads, (doesn't matter which one) pull out the plug, ground it with the lead attached, make sure the king lead is attached between the coil & the dizzy cap. Put a 12V feed direct to your coil, then take another lead from the negative & touch ground, don't hold it to ground just touch it. As you do that the plug should spark, if it does you've proved coil, king lead, rotor arm, Dizzy cap, plug lead & plug, so a good chunk of the circuit out of the way, if it doesn't you need to look at those components.