Technical Intermittant Electrical fault

[john2443]

My Uno 999 now and then just stops, and after a few minutes will start and be OK.

During the few minutes that it isn't working I've managed to narrow it down to the distributor - there are sparks coming out of the lead from the coil, but not getting to the plugs.

Any suggestions (other than replacing the whole dizzy!). I've got a spare dizzy cap and rotor arm so I'll try them.

I'm wondering if there's something that's getting hot, which would explain why it'll start after a few minutes, although today it stopped when doing 70 and then again when in a traffic queue which suggests that it isn't temperature!?

Thanks

 

[john2443]

I should have said that it's Electronic ignition.

 

[Chas Uno]

If the coil is giving sparks then that should mean that the distributor is sending the correct signals for it to fire. Thus if sparks are reaching the distributor cap then the only thing that would stop sparks reaching the plug/ HT leads is the rotor arm or the centre carbon electrode in the distributor cap. Rotor arms can, but rarely, fail. However, I've had a number of cars where the centre electrode in the distributor cap has either partially broken or the spring becomes weak and doesn't push it out far enough. Change the distributor cap first to try and rule that out.

If your problem only occured at high'ish temperature then the other culprit could be the ignition amplifier module (the silver finned unit on the distributor). Check to make sure this isn't getting too hot (it will be hot to touch under normal use but if it is very hot then it may be faulty). Also check the leads coming out of this unit as the insulation has a habit of failing causing shorting. Also make sure that the earth leads are clean and secure.

Hope this helps!

 

[john2443]

Thanks. That'll be what I'm doing tomorrow afternoon!

 

[alexGS]

My vote is with Chas (1986Uno45S) here. I think it's most likely to be the finned box on the distributor. Every Uno 45 driver should keep a spare in the boot

~Alex

 

[john2443]

HHHmmmm! It's run fine yesterday afternnon and this morning having changed the cap (didn't make and difference) then taken the dizzy apart, cleaned it and put it back together again.

So that leaves me with a running car, but no certainty about what was wrong!