Classic cars forum & vehicle restoration.

TonyBrooks · Joined: 02 Jan 2008 Posts: 108 Location: Maidenhead

The engine is a Ford Cortina GT 1500cc. I have fuel and I have power at the points but no spark at the plugs. I have changed coil, points & condenser to no avail. Sometimes, after turning the engine on the starter, when you release the ignition key, the engine almost starts. Its allmost as if the starter is drawing current preventing any spark at the plugs but in that split second that the key is released, some spark get through. Any thoughts would be much welcomed.

Tony

Penman · Joined: 23 Nov 2007 Posts: 4755 Location: Swindon, Wilts.

Hi
Does this engine have a ballast resistor?
I had a car which wouldn't deliver any spark when the starter was operating but did once it was off.
Changing the B R cured it.

Will it bump start?

edit

Just had a read of this and it might be the wiring that bypasses a B R.
http://images.google.co.uk/imgres?imgurl=http://www.classictruckshop.com/clubs/earlyburbs/projects/trouble/igndiagram.jpg&imgrefurl=http://www.classictruckshop.com/clubs/earlyburbs/projects/trouble/ignition.htm&usg=__YrJyYvUgS_gPiebBNNeS6RkZ3iY=&h=480&w=640&sz=43&hl=en&start=3&tbnid=ONr0oGAkleA4vM:&tbnh=103&tbnw=137&prev=/images%3Fq%3Dballast%2Bresistor%26gbv%3D2%26hl%3Den%26sa%3DG
Perhaps I just disturbed things enough to get mine working. Surprised

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Ray the rocker · Joined: 01 Aug 2008 Posts: 187 Location: south wales

Hi tony---try flicking the points with the ignition on and hold the HT lead from the coil about a quarter of an inch from an earthing point.if there is a nice spark---i would tend to look for problems within the ignition switch assy
cheers ray the rocker.....

ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire

I would also look at a ballast resistor / connection problem, if the resistor circuit has gone o/s then this would explain why the engine will only fire when the starter motor is turning. Put a temporary supply direct to the coil, don't leave it on for long though as a ballested coil won't like 12v.

Dave

michael1703 · Joined: 22 Jul 2009 Posts: 349 Location: suffolk

have you tried a new rotor arm?

is the coil good? could you try another one on it from a known working car?

i find the modern rotor arms arent as good as the ones made 15+ years ago

TonyBrooks · Joined: 02 Jan 2008 Posts: 108 Location: Maidenhead

Thanks for all the replies folks. I don't have a ballasted resitor fitted and have tried several coils. I will try a different ign. switch and get (yet another) rotor arm!

victor 101 · Joined: 03 Apr 2009 Posts: 446 Location: East Yorkshire

Run a temporary feed from battery live to switch side of coil, that will eliminate the ign switch rather than changing it on the off chance. But I dont think thats the fault. Do as Ray suggests and flick the points whilst holding the HT lead from the coil near the engine and see if it sparks, if it does do the same again, but this time on the top of the rotor arm, if it sparks your rotor needs replacing, while the cap is off check the carbon brush is okay. You could also connect a jump lead from the battery earth terminal to the engine, because if your engine earth lead is poor you wont have a spark.

TonyBrooks · Joined: 02 Jan 2008 Posts: 108 Location: Maidenhead

Problem sorted. A new Ignition switch and a new set of points cleared the issue. I think either the low tension lead was shorting inside the distributor or the condenser lead was making a poor contact. This coupled with the dodgy ign switch made trying to solve the problem difficult but got there in the end. Thanks for all the suggestions.

Jim.Walker · Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield

Are you sure it is "sorted"? Or have you cured lesser faults which have raised the voltage available at the contact points?
The fault sounds like the classic symptom of a poor earth between the contact points base plate and the engine block.
What happens is that battery voltage falls to about 11 volts with the engine cranking (normal), but when the starter switch is released the battery voltage jumps immediately to about 13 volts (also normal). That extra 2 volts is often enough to compensate for the bad earth and fire the ignition system and if the engine is still rotating and you release the starter switch at just the right moment it will often start.
Connect a 0-2 (max) voltmeter between the earth contact of the contact breaker points and the engine block with the points closed and the ignition on.
Anything greater than 0.2 volts is BAD. Nearer zero is better.
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