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No Sparks
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Author:  PDJ [ Sat Feb 25, 2012 5:28 pm ]
Post subject:  No Sparks
Good Evening y’all
After finally getting my moke back together the time came to try and start it. This is where my troubles began. Basically I have no spark. No spark coming from the coil and no spark between the points. The engine is a 998 and I think it’s a late 70's one from a Clubby. I've had the engine out whilst I painted the engine bay. The head and cam have been changed. The dizzy has been out. All wiring was labelled up before removal and is now back (hopefully in the right places)

So far I have..........
1. Changed the Coil (Bosch) and HT Leads.
The old one was open circuit across all terminals (it was pretty crusty). Disconnected the HT lead from the distributor and put it to the block (I even scraped off the paint) turned it over, no spark jump.
2. Changed the points and gapped to .016 and changed the condenser. Cranked the engine over, no spark. Turned the ignition on and manually opened the points, no spark.
3. Checked all the fuses. One dodgy one so I replaced it. Still no sparks.
4. Checked voltage going to the coil. 11.6V Ignition on. 8.6V engine cranking.
5. Checked all connections and replaced crimped terminals.
6. Checked the battery voltage. 12v.
7. Checked the wiring diagram and everything looks to be O.K. It has 2 wires on the – side of the coil. One to the Dizzy and I think the other is for the tachometer (according to the Haynes Manual)
8. Removed the paint from behind the earth strap to get a better earthing point.
So, after doing all of the above I still have no HT from the coil and no spark across the points.
I have no idea what to try next so any help would be greatly appreciated.
Author:  Mick [ Sat Feb 25, 2012 5:40 pm ]
Post subject: 
I think your voltage from the battery is too low. Once the engine starts cranking the voltage will drop again to maybe 9 or 10 volts. The starter draws maybe 100 amps, and if it struggles to get this then the battery voltage drops dramatically. Then there's not enough potential from the coil output then to jump the gap.

You need the battery to be around 13 volts and up. Although its only a small difference the 11volt measurement represents a massive lack of charge in the battery.

Give it a good solid charge, or if the battery is a dud swap it out with another and give it another go.
Author:  PDJ [ Sat Feb 25, 2012 5:51 pm ]
Post subject: 
I've had it charged up (overnight) a couple of times.
I've just got one out of my Peugeot and I'll put that on overnight and try again in the morning.

I know you should have 14+ volts when connected with the engine running but I though disconnected 12 volts was O.K. I'll know for sure tomorrow when the other is charged.

Just checked and I've got 12.7V on the battery.
The engine turns over like a lil rippa too.

Thanks.
Author:  Mick [ Sat Feb 25, 2012 6:11 pm ]
Post subject: 
PDJ wrote:
I've had it charged up (overnight) a couple of times.
I've just got one out of my Peugeot and I'll put that on overnight and try again in the morning.

I know you should have 14+ volts when connected with the engine running but I though disconnected 12 volts was O.K. I'll know for sure tomorrow when the other is charged.

Just checked and I've got 12.7V on the battery.
The engine turns over like a lil rippa too.

Thanks.


Watch the battery voltage as you turn it over, if it drops to single figures then there is definitely a problem. Try starting it with the jump leads still connected from the donor charge car and see if there is spark then. Even then, the amount of volts required at the spark plug goes up dramatically once the air in the cylinder is compressed.

Once we've ruled the battery out, what value of ohms do you get across your coil?

And although your condenser is new, they have been known to be dud from the box as well or there may be a short to ground with the points connections...but try one thing at a time.
Author:  PDJ [ Sat Feb 25, 2012 6:29 pm ]
Post subject: 
It was brand new and I got a Lucas one.
Can’t remember exactly what it tested out at but the ohms and k ohms where spot on to what I'd googled.
I even took it off and checked it again to make sure once I'd tried with no success.
As you've said though it seems a big voltage drop when cranking over.
Author:  simon k [ Sat Feb 25, 2012 6:32 pm ]
Post subject: 
disconnect everything except the necessary wires on the coil - 12V on the +'ve side and the wire to the coil on the -'ve side

you might as well take the 12v direct from the battery side of the starter solenoid - get it as simple as possible to find your sparks

edit: flicking the points open (from closed) with a screwdriver will make a spark across the points, good way to check connections
Author:  Mick [ Sat Feb 25, 2012 6:34 pm ]
Post subject: 
PDJ wrote:
It was brand new and I got a Lucas one.
Can’t remember exactly what it tested out at but the ohms and k ohms where spot on to what I'd googled.
I even took it off and checked it again to make sure once I'd tried with no success.
As you've said though it seems a big voltage drop when cranking over.


Yes, with voltage at the coil, a new coil and points and condenser then its reasonable it should spark. I really suggest backing a car up and jump starting with the other car connected through jumper leads. It will hold a near perfect voltage in this case and show the battery up if it's at fault.
Author:  PDJ [ Sat Feb 25, 2012 6:44 pm ]
Post subject: 
edit: flicking the points open (from closed) with a screwdriver will make a spark across the points, good way to check connections[/quote]

I did this as my "operated manually" with no sign of a spark.
I think I need some known good power as Mick says and check the on load voltage drop. Fingers crossed it’s that simple. The thing is it turns over so freely. I'd have thought that a week battery would have it turning over slowly.
Saying that though all my cars have had fuel injection for the past 14 years. I've been spoiled :lol:
Author:  Mick [ Sat Feb 25, 2012 6:52 pm ]
Post subject: 
PDJ wrote:

I did this as my "operated manually" with no sign of a spark.
I think I need some known good power as Mick says and check the on load voltage drop. Fingers crossed it’s that simple. The thing is it turns over so freely. I'd have thought that a week battery would have it turning over slowly.
Saying that though all my cars have had fuel injection for the past 14 years. I've been spoiled :lol:


I'm a little concerned that it did not spark even without the battery turning the car over. I might be proven wrong yet, it may be your new condenser. You could try disconnecting the condenser and retrying Simon's trick.
Author:  drmini in aust [ Sat Feb 25, 2012 7:01 pm ]
Post subject: 
With the points open and ignition on, pull the `-' (to dizzy) wire off the coil and touch it back on there. If it sparks you have a short to ground in the points/condenser wiring in the dizzy.
Author:  simon k [ Sat Feb 25, 2012 7:15 pm ]
Post subject: 
it's not the battery - you can push start a car with a dead battery, right? if the battery will turn the motor over, then that ain't it
Author:  Mick [ Sat Feb 25, 2012 7:25 pm ]
Post subject: 
simon k wrote:
it's not the battery - you can push start a car with a dead battery, right? if the battery will turn the motor over, then that ain't it


When the battery gets low enough to turn the motor over, the compression in the cylinder will blow out the spark (well not actually blow, but it needs a higher voltage in a dense environment to make the jump, like when you over boost a turbocharged car. It begins to miss). The battery does all it can to supply the hungry starter motor and voltage drops significantly. This is reflected in the spark voltage proportionate to the input voltage and the transformer ratio of the coil.
If you're really tricky, and you know the problem you can get lucky and start a low battery car by letting the key go at the right spot. The car will flick over compression, and the voltage will return strong enough to give a decent spark in the nick of time. Useful on a cold morning when you're getting to be late for work.
Author:  Rob1970 [ Sun Feb 26, 2012 1:49 am ]
Post subject: 
Disconnect the tacho wire from the coil to make sure there's not a short in that part of the circuit.
If there is a short to earth on the negative side of the coil you wont get any spark as the coil needs the break in connection to discharge then recharge. Ie the points closing and opening will do nothing if the tach wire is shorted to earth.
Just another 2 cents worth to the cause.
Cheers Rob
Author:  Convertible Mini [ Sun Feb 26, 2012 5:47 am ]
Post subject:  no spark.
Rob beat me to it. Disconnect the tacho wire from the coil and leave only the ignition feed on the + side and the wire that goes to the Dizzy on the - side. Also make sure the insulators on the points are correctly placed. Some points are tricky to fit and easy to place the wire terminal on wrong side of insulator causing a short like the points are permanently shut. When you sort this out fit one of my electronic ignition kits to it. (But first find the problem or you will blow it up too)
Author:  PDJ [ Sun Feb 26, 2012 9:02 am ]
Post subject: 
I made up a lead to go from the coil to the dizzy (to bypass the tacho lead), no dice.
I then disconnected the lead to the dizzy and checked the resistance between the dizzy lead and the earth strap to the body. This showed a direct short :?
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