sudden ignition failure

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barry young
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sudden ignition failure

Post by barry young »

Backed the frequently used 1957 saloon out of the garage and onto the street and then loaded up with two children and a dog the engine suddenly stopped (no spluttering first).

I've changed the points, rotor arm and condenser for new Distributer Dr items. There didn't seem to be a spark at the plug at first though now there is - I changed two ht caps after finding that putting the probe from my door bell circuit tester in the ht cap and the other one inside the terminal in the distributer cap wouldn't sound the bell. Can't see and crack or tracking on the distributer cap which is an original Lucas side entry one I bought at the National Rally about five years ago.

Still won't start. I've checked that petrol is pumping.

Strangely, the horn, radio and interior light won't work either. Neither fuse has blown.

I've no idea what's wrong with it. Can anybody point me in a likely direction.
myoldjalopy
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Re: sudden ignition failure

Post by myoldjalopy »

To be honest, there are a number of possibilities as to why it won't fire up. Now that you have new points, condensor and rotor arm now fitted, and you are sure fuel is getting through, I would go back to basics and:
1. Check there is a good spark at the king lead from the coil - if there is, then re-fit it to the dizzy cap and check eack plug in turn for a spark. If they don't spark the problem is likely the distributor cap (did you check the carbon bush in the centre of the cap moves freely and the spring is OK?).
2. If there is no spark at the king lead then further investigation is needed into the coil and various electrical connections. Rather than run through the whole sequence of tests now, it would be better if you report back first on the spark tests at the king lead and the plugs.
3. If the interior light and horn are not working but the fuses are OK, it may be bad connections in the fuse box - I'd clean them all up.
simmitc
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Re: sudden ignition failure

Post by simmitc »

Check the battery connections, especially the earth. Do all other electrical items work OK - lights, indicators, wipers etc? I suspect that the horn / radio / interior light are unconnected with ignition failure, but worth checking everything.

After changing the points, is the timing OK?

Remove all plugs. Take an HT lead direct from the coil so that the other end is about 1/4 inch away form the block. Ignition on and turn the enigne over, do you get a nice strong spark? If yes, the replace king lead from coil to cap and repeat the test using the ends of each plug lead in turn and confirm that all four provide good sparks.
barry young
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Re: sudden ignition failure

Post by barry young »

I'll check the sparking situation at all four spark plugs again tomorrow. I wonder if the sudden radio interference that started a few weeks ago might indicate a duff ht cable or two.
myoldjalopy
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Re: sudden ignition failure

Post by myoldjalopy »

Check for a spark at the king lead first. If there is a good spark, then replace the king lead in the dizzy and try the plugs one at a time. Let us know what happens...........
barry young
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Re: sudden ignition failure

Post by barry young »

There's a spark at each plug but the engine won't start. The battery's fully charged. Still no life in the horn, radio and interior light although I've cleaned the contacts round both fuses. I never drive without the radio on which is what makes me think this must have something to do with the non starting situation. All other electrics are working fine. Day three of fiddling now with no results.
barry young
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Re: sudden ignition failure

Post by barry young »

checking resistance of the first HT lead with a multimeter set to 20,000 ohms there's no reading. Signifficant?

Solved the mystery of the horn / radio / interior light. Although the fuse looked sound there was no current passing through and when I took it out again one of the ends fell off. Horn etc no working fine.
simmitc
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Re: sudden ignition failure

Post by simmitc »

If you have a spark at each plug then that rules out ignition - regardless of lack of power to other systems, there is power getting to the coil. That leaves a few possibilities. In no particular order: Lack of compression, lack of fuel, spark at wrong time.

With all plugs fitted and ignition off, handbrake on, gear in neutral. turn the engine on the hanlde. You should easily feel good compression on each turn. I do not expect this to be an issue, just ruling it out.

You say that the fuel pump is working, but you might have a blocked jet in the carb. Unlikely to have happened so suddenly, but take the top off the floar chamber and look to see if there is any debris in the bottom. You can also check the operation of the float valve.

Now to the plugs - are the leads on the correct plug? It's very easy to swap them round and then the spark is at the wrong cylinder and so the engine does not run. Remove spark plugs, put your thumb over number 1 plug hole (front of engine) and turn engine by hand until you feel compression. Once the piston is at TDC (you can see it through the plug hole) remove the dizzy cap and check where the rotor arm is pointing. Make sure that the corresponding HT lead is going to number 1 plug, then check the order of the rest: 1-3-4-2 anti-clockwise around the cap.

If still no joy, double check the timing to ensure that the points are opening when the timing marks are aligned. Even though the best timing will be a little different, the static settings as per the book should still ensure that it at least starts.

For the horn, light and radio, do you have a multimeter available as this will make fault finding much easier.
kennatt
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Re: sudden ignition failure

Post by kennatt »

before stripping anything tip some fuel into the carb,after removing filter and see if it now fires up.,indicating fuel problem,probably by a sticking needle valve in the float, pump working but not letting fuel into float chamber.
barry young
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Re: sudden ignition failure

Post by barry young »

Thanks for the advice, everyone. There's fuel in the float chamber, the plugs get wet with fuel when I try to start it ( although the plug in cylinder no 1 seems not to be). There's plenty of compression judging by turning the starting handle. The plug leads are all in the correct place having checked that each piston at tdc corresponds to the rotar arm pointing at the right place.

What about the resistance check I did on the ht caps? Is this just a red herring or have I misunderstood something. I tried to get a couple of ht caps from Halfords to swap them but was told they're no longer made (!)

I have no idea how to check the timing. When trying to start up it does fire up for just a second but sounds like less than four cylinders.
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mobylette
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Re: sudden ignition failure

Post by mobylette »

Try swapping back the old condenser and rotor arm (one at a time) to eliminate these.
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ianmack
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Re: sudden ignition failure

Post by ianmack »

Ht plug caps are still available, I got a set online. Several ebay sellers list new ones. The traditional type aren’t used on modern cars so high street car shops probably won’t have them.

Typical clueless Halfords!
simmitc
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Re: sudden ignition failure

Post by simmitc »

The original report said
the engine suddenly stopped (no spluttering first).
Then we got
Still won't start.
Followed by
When trying to start up it does fire up for just a second but sounds like less than four cylinders.
There is a slight conflict between the statements which could point to different problems. Has the short run on fewer than four cylinders started since we did the fault finding, or has it always been like that?

When fitting the points, did you set the gap correctly? Sometimes what appear to be similar points can have a slightly different profile that causes them to open at a different point from the old set, so it is always best to check the timing. I've found that many times there is no difference, but now and then it can be a good few degrees. Is the distributor clamp tight, or is it possible that the dizzy has moved round a bit?

Have you tried the fuel into the carb test suggested above?

Do you have a workshop manual to look at timing? If not then we can go through it here, but if you have the manual then it's all in there ready.
pgp001
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Re: sudden ignition failure

Post by pgp001 »

Barry

You say you have a spark at each plug, what colour is it.
Ideally it should be blue and you should be able to hear it. If you have a very weak whitish coloured spark with the plug removed from the cylinder, then it will struggle to work under compression when you replace it.

I had a recent instance of this on a friends Minor, it turned out the coil had failed. His car stopped in exactly the same ways yours did.
He messed around swapping all sorts of things, plugs, points and condenser etc. It looked as thought there was a spark but not a very good one and it was not until we tried my spare coil and then it fired up straight away.

Everyone will tell you "Its never the coil" but my own experiences both with Minors and Austin 7's does not bear that statement out.

It is unlikely to be fuel related from what you have said, so must be a component failure in the ignition system, you have tried everything else by the sounds of it, so I would either change the coil or borrow one and try it out.

Phil
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Re: sudden ignition failure

Post by Shropshiremoggie »

Had the same issue with mine , it WAS the coil !!!!!
barry young
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Re: sudden ignition failure

Post by barry young »

Th dizzy clamp seems tight and I don't think it's moved. The new points were the same make as the ones I took out and I'm pretty sure I've set the gap right. Where would the petrol into the carb test go if the float chamber's already full ?- the plug tips are getting wet with fuel.

The slight beginning to fire has happened since I've been fiddling but it's really only for a second or two. The spark at the plugs doesn't look particularly strong.

I've had coil problems myself in the past. The last was a Lucas coil from ESM which failed after less than six months. The AA man put a meter across the two attachment points and found an open circuit. He found a new NGK coil and fitted it - I suppose I could check the resistance. I hadn't thought of the coil, it's less than a year old.
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Re: sudden ignition failure

Post by irmscher »

As BMC Roy would of said its never the coil :lol: :lol: Oh but sometimes it is :D
oliver90owner
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Re: sudden ignition failure

Post by oliver90owner »

If you can draw a blue spark of in excess of 6mm from the king lead, the coil will be OK (at least while cold).

If the current through the coil is limited, the spark will be weak. It should be around 4A when connected resistively. Current reduces as engine revs rise.

If the spark is yellowish, suspect the condenser. Testing is with multimeter or by substitution.

The points could be restricting the coil current if not properly installed. Usually it is a matter of working OK, or no current at all, when closed.

The ‘pigtail’ lead is an occasional problem causing intermittent operation (and possibly subject to vibration).

The rotor arm is easily appraised - spark or no spark being transferred to the distributor lead connectors.

The distributor cap - it is usually easy to see tracking beween electrodes or earth. Sometimes distributor cap and rotor can need substitution to sort out which is at fault - but not often.

Leads and plugs - they don’t often all fail together!

The Kettering ignition is a simple circuit. Changing several items, without sensible diagnosis beforehand, is the usual easy way to not find the real fault (and waste resources at the same time). With a multimeter (or test lamp) and insulated screwdriver, it should take no longer than about ten minutes to isolate an ignition problem such as this.
myoldjalopy
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Re: sudden ignition failure

Post by myoldjalopy »

If the OP has recently fitted Distributor Doctor points, condensor and rotor it is unlikely to be these that are the issue. However, now he says the spark at the plugs "doesn't look particularly strong".....so the crucial question has to be ' what is the spark like from the king lead'? We have never had feedback about this and the answer will give us an important clue. Nor have we had feedback about the condition of the carbon bush and spring in the dizzy cap which I mentioned right at the beginning of this thread.....
oliver90owner
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Re: sudden ignition failure

Post by oliver90owner »

MOJ,

I deal with more magnetoes than coil systems these days. I have only once changed a condenser in an old magneto, I think.

Kettering systems are so easy to diagnose, and results of the basic tests rarely seem to be forthcoming, so I keep out of these recurring problems as much as possible. When I joined this forum, the cry was always ‘change the condenser’. No testing, no diagnosis, just assumption. Not a good way of sorting problems, even though some problems were not even electrical.

Many people look no further than the assumed cure to their last fault. Imagine how we would get on without fault codes and computer diagnosis checks on modern engines!
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