Not firing

[MarkCW]

Hi all,

Hope everyone had a lovely Chrimbo.

Now to the more distressing problem i seem to have:
Out for a drive today, seemed a bit lumpy then started to cough and splutter, followed by a complete lack of power (despite trying to keep the revs up in a low gear), followed by it dying.
Turned over but wouldn't fire.
Got towed home (the shame) where i have pulled the leads off, dizzy cap, rotor etc and then checked each part.
I have a very healthy spark at the coil into the cap but no spark from the cap to the leads.
I'm scratching my head as to why, my only guess is that the cap is US. It has no markings on it but its blue - so i have no idea if its the Lucus or a copy, it seems to be in good shape, no pitting, spring is good and the spark into it from the coil, as i said, is very strong.
Am i on the right track by changing the cap or am i missing something simple?

Any help is appreciated, currently stranded at my parents in mid Wales, not many places round here to get parts either!

Thanks in advnace
Mark

[spend]

Easiest if you can borrow cap & rotor off a friendly LR/RR owner (I wonder why so many of us also own them as well). 2nd LR/RR can be cheaper than buying bits to swap out for diagnosis

Dave

[MarkCW]

Thanks Spend - i was hoping you'd be along to help!
I take it i'm on the right track then?
Problem with all the farmers up here is they run diesel versions - cheap skates!
Will try and get hold of cap and arm tomorrow to try.

Mark

[freddytin]

Sounds like it is shorting through the rotor arm.

With the cap removed hold the coil lead close to the centre of the arm whilst cranking . It should not be able to track if the rotor insulation is OK

[spend]

Depends if you fired the coil manually avoiding the ign amp? Apparently you can test the amp by flicking the rotor arm and seeing if the coil generates a spark (thanks to an old f@rt from Longbridge), which I didn't discover until recently - it is also possible to check the voltage at the coil using this method (but I got too pissed to remember the explanation )

Dave

[MarkCW]

freddytin said:

Sounds like it is shorting through the rotor arm.

With the cap removed hold the coil lead close to the centre of the arm whilst cranking . It should not be able to track if the rotor insulation is OK

Thank you,
It would appear that this is what is causing the problem, tried as you described and its tracking from the spring at the top through the ceramic at the bottom.
Funny though as i can see no visble signs of deteriation on the arm.
Oh well, off to find a local LR/RR place tomorrow (or scrounge one off a local!) and shall fit new arm and dizzy.
Fingers crossed this will cure it.
At least its given me an excuse to take it apart and clean it all if nothing else, and by all that is holy at this time of year - those plugs by the bulkhead are....well, you know!

[MarkCW]

freddytin said:

Sounds like it is shorting through the rotor arm.

With the cap removed hold the coil lead close to the centre of the arm whilst cranking . It should not be able to track if the rotor insulation is OK

Thank you,
It would appear that this is what is causing the problem, tried as you described and its tracking from the spring at the top through the ceramic at the bottom.
Funny though as i can see no visble signs of deteriation on the arm.
Oh well, off to find a local LR/RR place tomorrow (or scrounge one off a local!) and shall fit new arm and dizzy.
Fingers crossed this will cure it.
At least its given me an excuse to take it apart and clean it all if nothing else, and by all that is holy at this time of year - those plugs by the bulkhead are....well, you know!

Mark