Ignition problem? I'm confused, help...!!!

G

grifterkid

Member
Ok so my 1974 P6B has been fine, up until recently... It had a kind of mis-fire and then it died a couple of weeks ago. the recovery chap diagnosed an ignition fault as there was a spark but it didn't seem to be getting through to produce power. It went to the garage to have the points, condenser, rotor arm, distributor cap etc changed and all seemed well... Today it was running fine in the morning and then later on it decided to die again, same as before. Misfire, lack of power, death! When I turned the ignition key it churns but it will not turn over! Half an hour later, I returned to the car, turned the key and it sprang into life... this is causing me no end of headaches as I really do like this motor but it's severely testing me (and my wife)...! Can anybody offer any advice? DOes it sound like an ignition problem? Do I need a new distributor? Please help...!!!
 
it churns but it will not turn over! Half
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Sorry but do you mean it turns over but doesn't fire ? Have you checked for spark at the plugs and fuel flow to the carbs ?

Does it die suddenly or cough and splutter first ?
 
Did they also change the coil?

I had a wierd ignition problem many years ago. It was traced to a faulty coil that was gradually killing my condensor. Changing all the usual ignition circuitry fixed it until the next condensor died. Changing the coil fixed everything.

If not I'd try a new coil, but make sure you get one appropriate to whether or not you have a ballast resistor.

Brian.
 
DaveHerns said:
it churns but it will not turn over! Half
Click to expand...

Sorry but do you mean it turns over but doesn't fire ? Have you checked for spark at the plugs and fuel flow to the carbs ?

Does it die suddenly or cough and splutter first ?
Click to expand...
It turns over but doesn't fire... It gives a little cough and splutter as if to say "I don't want to play any more" then nothing, it dies... Then it'll turn over then won't fire but, as I said, half an hour later it'll fire up perfectly again. The question is, how long for as the last time it did this it just died again a few miles later...!!!
 
I would agree that the coil could be the problem.

Coils and condensers often work when cold but when hot ( after the car has been running for a while ) they tend to short circuit and don't work. Condensers sometimes will be OK at tickover but rev or load the engine and then the spark will be too weak.

Also just check that there is petrol being pumped up.
 
Be sure that the new coil that you purchase is the type that is to be used with a ballast resistor. It should say on the coil itself, but you can always measure the primary resistance which will typically be between 1.2 and 1.5 ohms.

Ron.
 
Or could it be the ballast resistor wire is faulty/has burnt through the insulation and is making erratic contact to earth?
 
darth sidious wrote,..
Or could it be the ballast resistor wire is faulty/has burnt through the insulation and is making erratic contact to earth?
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As grifterkid's engine won't start, I would be inclined to rule out the ballast resistor wire, as it is bypassed for starting. Once the engine fires and the ignition key is moved back from position three to position two, the 12 volts applied by the starter solenoid to the coil returns to zero care of the starter relay dropping out. From this point on, if the ballast resistor wire is the culprit then running issues will present.

Ron.
 
So coil it may be then...?! If so this is, typically, the only bit that hasn't been replaced since I purchased the car...!!!
 
There have been experiences on the forum recently of condensors lasting only a very short time and with similar symptoms. I'd try that first before you go into renew everything mode!

Chris
 
chrisyork said:
There have been experiences on the forum recently of condensors lasting only a very short time and with similar symptoms. I'd try that first before you go into renew everything mode!

Chris
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The condensor is literally about a week old...!
 
SydneyRoverP6B said:
As grifterkid's engine won't start, I would be inclined to rule out the ballast resistor wire, as it is bypassed for starting. Once the engine fires and the ignition key is moved back from position three to position two, the 12 volts applied by the starter solenoid to the coil returns to zero care of the starter relay dropping out. From this point on, if the ballast resistor wire is the culprit then running issues will present. <== But there are running issues; the bloody thing won't run reliably as it should! :p

Ron.
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But grifterkid said
grifterkid said:
It turns over but doesn't fire... It gives a little cough and splutter as if to say "I don't want to play any more" then nothing, it dies... Then it'll turn over then won't fire but, as I said, half an hour later it'll fire up perfectly again. The question is, how long for as the last time it did this it just died again a few miles later...!!!
Click to expand...

By "cough and splutter" I assume he means it fires for a bit (maybe while the starter solenoid is bypassing the ballast resistor and giving full battery volts to the coil), but stops (maybe after the key is released, when the coil is (at least meant to be) fed via the ballast resistor) IMHO, I think you are unwise to rule it out.

"half an hour later it'll fire up perfectly again". Though that may be a bad connection somewhere, it also suggests an erratic dead short caused by insulation breakdown. As you and others quite rightly suggest, it could be a condensor or coil problem. But IMHO it could also be the ballast wire making erratic contact to earth somewhere. (One possible effect of this though is that the wire may get very hot and burn the insulation!)

I admit that I may well be barking up the wrong tree; It's hard to fault-find from afar, and would be much easier if I was there with the car!
 
grifterkid said:
Where is the 'ballast wire' please...?!
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I think it's in the wiring loom. One end of it may well be visible in the engine compartment (maybe entering into a connector). Assuming they did the same on your car as was on our old 1972 2000Auto, it's a white-pink wire (IIRC). (It needed to be replaced on ours in 1988, it caused the car to not start and you could actually sniff a burning smell! :-S) A friend who had a 2200TC years later also had to have theirs replaced. Again, a burning smell was evident.

It's a bloody nightmare to change though! Best left to a competent auto-electrician.

BTW I'm not saying for certain it is that, just it may be. It could easily be the condensor, coil et al, as the others say. Check them first!
 
If the ballast wire has burnt out it would be easier to replace it with ordinary wire and a ceramic stand-alone ballast resistor
 
Hotwire the coil as a temporary measure and if it runs then you could assume that there is a fault with the ballasted supply. Alternatively put a voltmeter on it to see what voltage you've got there.

New condensers are a known problem and can fail in far less than a week.

Start again from the basics and work through everything again in a systematic way.
 
Check the P6 News index for an article on ballast resistors. Apparently they are very reliable and very seldom go wrong. On my '72 3500S the ballast resistor is built into the wire that runs from the rev counter to the coil. Harvey's suggestion to check voltages is best thing to do. The wire itself is dead easy to replace and certainly does not need a competent auto electrican.

Dave
 
Dave3066 said:
Check the P6 News index for an article on ballast resistors. Apparently they are very reliable and very seldom go wrong. On my '72 3500S the ballast resistor is built into the wire that runs from the rev counter to the coil. Harvey's suggestion to check voltages is best thing to do. The wire itself is dead easy to replace and certainly does not need a competent auto electrican. <== I beg to differ with you there, Dave! The wire on our old 72 2000Auto (not a V8, I admit, maybe it's different on them!) went into the loom quite "deeply". Even an old hardened mechanic of the P6 era said he would hate having to replace the wire!

Dave
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This is just my own humble opinion, btw! :-

Reading the article mentioned, and maybe reading too much between the lines, that article gives maybe a false sense of security about the ballasts. Certainly they may well be very reliable for a long time, but still you must remember even the youngest P6 is 32 years old, that is quite an age for a car! Speaking from my experience with our 2000Auto in 1988 (when it was 16 years old), and a friends 2200TC in 1994 (IIRC, cannot recall it's year, but I assume it was at least 16 years old at the time) (Admittedly, that is only 2), they can go faulty.

Good idea from Harvey, though! :)

If grifterkid feels competent to do it, then of course I wish him luck. (Assuming for the moment that is the problem with his car!)
 
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