Re: [doc] Stalling After 5 minutes

[Nick Tomlinson <nickandkathryntomlinson@xxxxxxxxxxx>]

Sounds like its electrical (going on your description)
 
Start by using an oscilloscope/ dwell meter to see if the coil is being switched to earth by the ignition amplifier.
 
If you don't have any of this equipment then you could perform a quick check for this is.
With the ignition on and in position no. 2 (dash board lights lit), remove the vacuum pipe from the distributor. Put another pipe on the vacuum advance and then suck it until you get resistance. This will move the baseplate round.
When you let go of the pipe and air rushes in the advance will be lost, the baseplate will move, it will induce/ change the field near the pick up in the distributor, the signal will be amplified by the ignition amplifier (fed from fuse #1 from main relay from top of my head) and will switch the earth side of the coil. This switching of the coil is also connected to the fuel pump relay that in turn operates the fuel pump and fuel circuit (computer?) that operated frequency valve near the cylinder head. If you can hear them buzz for a second then you know this side of the ignition system works. If you have no spark but this works then it is likely to be temperature related with the coil. You can confirm this by taking resistance readings of the coil when it is in a good state and when you get no spark. (Obviously without the engine running, ignition key out and all of the coil terminals removed including the HT lead).
 
Sounds a bit long winded but its a quick test and saves having to remove the fiddly coil cover.
 
How did you check for a spark? Did you remove the main lead out and see if you got a blue spark? This would only check for main HT. I would use a clip over timing light and see if you get an even fire from the flashing light.
 
Hope this helps,
 
NickT.

James Macpherson <james.macpherson@xxxxxxxxxx> wrote:


I think this might be the problem I first thought was the fuel pickup
problem I emailed about last week.

After more investigation I realised the car doesn't sputter or cough
like a fuel starvation problem it just stops like you have switched the
key off. So I did so further tests.

If I run the car from cold within about 5 minutes the car with stop and
not restart. 
There is no spark at the spark plug but after about 5 minutes more the
car will restart and will run without
problems for the rest of the journey. Then once left for a few hours it
will do the same again.

I've got to the point of running it on the driveway for 5 mins letting
it stop and waiting another 5 mins then starting it again before I can
go anywhere.

Anyone got any ideas what can cause no spark after 5min then fix itself
again?

James
doc 129
vin 2250



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