No sparks

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hdavy
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No sparks

Post by hdavy »

I was having trouble with (side valve) engine running but had sparks on all cylinders. I then removed, torqued and replaced cylinder head but after that no sparks. I had not done anything to the electrics. Ignition key on shows ingnition warning light OK. Test bulb lights across battery - car is positive earth. Bulb lights from both negative and positive coil terminals to the positive battery earth terminal. Neither will light to battery negative. There is a black and white lead to the main loom from the positive coil terminal and a white lead coil positive to loom.
There is a white lead from dash (presume from ignition switch) to the low tension connection on the side of the distributor which does not light test bulb. I presume that should be a positive connection? There is high tension coil to distributor. Ouch! Distributor cap connections look OK.
Before I grovel under dash would like advice and comments on the whole set up.
oliver90owner
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Re: No sparks

Post by oliver90owner »

For your information only. The ignition light actually has nothing to do with the ignition system apart from indicating the ignition switch is in the on position and the battery is not being charged. Nothing more!

The positive and negative connections on the coil are better described as ‘more positive’ and ’more negative’. In your case (of positive earth) the positive will be closer of the two to the earth and the negative will be closer to the battery live.

Now let’s get down to diagnosis of the ignition circuit.

Remove the king lead (the HT lead from coil to distributor cap) from the cap. Remove the distributor cap and turn over the engine until the contact points are closed. Now turn on the ignition switch (the key) and while holding the bare end of the king lead close to an earth (engine will do) use an insulated screwdriver to carefully open the contact points. Each time the points are opened, there should be a strong blue spark between the king lead and earthing point. It should easily jump 6mm, and likely more. It should be audible, too!

If that is the case you either have a distribution problem (rotor missing or dead). the points are not closing properly (unlikely), a leaky distributor cap or the rotor has failed (or has been removed and not replaced!)

If no spark, coil could be dead, the contact points are not allowing current to flow through the coil while closed (should be about 4Amps), or there is a high resistance feed to, or from, the coil (the ‘pigtail lead can often be at fault).

If the spark is yellow and weak, it could indicate a low current through the coil (high resistance connection/lead) or that the condenser is faulty.

Do this test and report back with the results. We can then better isolate the problem, within the system, to one of a few faults.

RAB
hdavy
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Re: No sparks

Post by hdavy »

Wow thanks. Will take a while because I can't get starting handle through without taking bumper off which is why I have not turned the engine manually yet!
oliver90owner
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Re: No spark

Post by oliver90owner »

You could bump it over with the starter motor, until it rests with closed points, or put into a suitable gear and gently rock the vehicle forwards or backwards to turn the engine a tad. Another alternative is to turn over the engine with the fan belt. No need for a starting handle as it needs less than one half of a turn.
RobThomas
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Re: No sparks

Post by RobThomas »

Hello again, Hugh.

On mine the shaft going up to the Dissy had been cut away so that it became possible to slot the Dissy back in 180 degrees out, even if it had been left in the head when the gasket was changed. That took a whole heap of thinking to work out!

Is it the Green Saloon? Did you ever sell the old Alta head from it?

The normal run is a white lead from the ignition switch down to the "Non earth" terminal on the coil (in your case + or SW) and then a white/black lead from whichever terminal on the coil matches the earth on the battery that then runs over to the dissy. Oversimplified, but hopefully it will give you a starting point.

Cheers

Rob
Cardiff, UK
hdavy
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Re: No sparks

Post by hdavy »

Rob. Yes the green one. I eventually sold the Alta head for £2000 to a guy in Oz. Under pressure I am looking to sell the car and several useful spares but don't want to try unless I can get it to run. Also a few people want to see photos so I need it out of the garage.
hdavy
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Re: No sparks

Post by hdavy »

OK guys. did RAB test and no HT spark when points are opened. So next I will check whether there is current between coil and points when they are closed. RAB which is 'pigtail' lead?
Rob I should have said I have and black and white from positive (which I presume is effectively 'SW' terminal) to loom and white lead from coil negative to loom.
All- The lead coming out of the dash is going to the LT connection on the side of the distributor is that right?
RobThomas
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Re: No sparks

Post by RobThomas »

hfiutoiyp.jpg
hfiutoiyp.jpg (282.04 KiB) Viewed 2396 times
White from ignition switch to (on yours SW or -ve) coil, white/black from the other coil terminal to the distributor. I didn't post this pic up before because I also have a white/grey wire added to run my electronic revcounter and that makes the photo confusing.

Plain white on one side of the coil, white with black from the other side , through the loom and down to the distributor.
Cardiff, UK
oliver90owner
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Re: No sparks

Post by oliver90owner »

Pigtail lead is the one between coil and points. It is a prime candidate to get damaged.

To test the coil you can do the spark test by changing the coil connection with a piece of wire and simply touching and removing it to an earth point. You would then know whether the problem was upstream or downstream from the coil. To test for the supply to the coil you could connect a test lead directly to the battery. From all these simple little tests, the fault will easily be isolated.

Note: The spark from the king lead will be weak, if testing without the condenser in circuit and there will be more sparking (at disconnection) at the coil/earth point.

RAB
hdavy
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Re: No sparks

Post by hdavy »

Rob where is the white lead from the coil attached to the dizzie? It is of course different from mine.
hdavy
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Re: No sparks

Post by hdavy »

a lead from either coil terminal will spark to earth battery terminal.
myoldjalopy
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Re: No sparks

Post by myoldjalopy »

Ok, so there is voltage at both low tension connections on the coil.
So, as has been suggested earlier, test the coil itself. Remove both coil low tension leads, leave the king lead on the coil but take the other end out from the dizzy cap and position it on the engine block as described earlier for testing for a spark .
Run a wire from the -ive terminal of the battery (if you have +ive earth as stated in your original post) to the -ive/SW connection on the coil. This bypasses all the wiring from the battery via the ignition switch to the coil (although I suspect this wiring is OK as you say you have voltage at the SW connection).
Now connect another wire to the +ive/CB connection on the coil. By quickly touching and removing the other end of this +ive/CB wire to earth (car body would do) you will be simulating the action of the points in the dizzy. If the coil is good you should see a little spark where you touch and remove the low tension wire and a nice fat blue spark from the end of the king lead to the block.
If it doesn't spark, suspect the coil. If it does spark, suspect the wiring to the dizzy, or something shorting out in the dizzy (like the points or the little pigtail connecting wire Oliver90 mentioned earlier).
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