5 replies to this topic

[gingerbrick]

so far iv been able get away with searching the forums for answers, but that is a real Brian teaser for me anyway.

took the mini to mot yesterday, it past but on the road home started hesitating on acceleration as if their was no oil in the dashpot. it was getting worse very quickly to be dashpot oil so i thought id through fuel in incase my gage was wrong. didn't help just got worse until the engine eventually stopped and wouldn't start again, tried all i could at the side of the road but had to get a tow.

mini: 1992, carbed, 1000cc

checked for fuel or dirt in carb float bowl, wetting plugs. plugs in good condition so it was running well(when it was running)

discovered no spark after distributer, good spark straight out of coil (checked every thing before coil points, wiring etc), ht leads checked, tested cap and rotor arm. 

Means the only thing left is the timing but everything is tightened nothing could have moved 

is their any thing in the disco. linkage that could have slipped?

could a disco go like this, mechanical advance seized or something?

with points open full the rotor arm sit about half way between the points of the cap, take it that ain't right? 

is their anything else it could be, ive ran out of ideas and am not to keen on doing timing?

help is much appreciated, might just me stuck this time

[KernowCooper]

If you have what you said "discovered no spark after distributor, good spark straight out of coil" then the problems with the HT circuit.

 

If you have a constant spark from the coil king lead to a head stud when cranking and no spark from the ignition leads then the problem lies either the cap tracking, the carbon brush worn away, the rotor arm failed. I doubt the leads are faulty as they wont all develop a fault at once. Is the spark a blue spark when held to a head stud upon cranking.

 

You have a fault which stopped the car, so its not a issue with the advance weights

 

just put a voltmeter on the coil + and take a voltage reading to confirm you have a constant voltage there, and if you have a white/pink and a white/yellow on the coil + you have a ballast system and it should be 9v running and 12+ when cranking.

 

Check and come back if you can't find it

[adampat84]

Dave is the man when it come to electrics... so try what ever he says first. I will add this as it was my personal experience:

 

I had the same problem with mine.. had spark from the coil but nothing after the dizzy to the plugs.. i swapped everything apart from the rotor cap and it still wasn't working.. (Coil, leads, plugs, dizzy cap, points and even fitted electronic ignition)

 

I then decided to replace the entire dizzy with a powerspark points 25d (I have an a-series not a+) off the eBay for £30 and it started first time..

 

When i have a few minutes i will try putting the new cap on the old dizzy.. but for the time being i'm just happy it works.

 

Is a little bit of an extreme method but it worked and for £30 with a 3 year warranty i can't really complain.

 

Just my two pence worth.

[Tamworthbay]

I would follow Dave's advice, but I would also add that I changed to leccy ignition on my daily MGB GT because or poor quality condensers, I was averaging a new one every 6-9months and the symptoms are exactly as you describe. I am not normally a fan of swapping components before you know for sure they are to blame but its always worth carrying a spare condensor and it only takes a minute to swap. There is a way to cheat that I was shown once but for the life of me I can't remember it. You connect a condensor on a length of wire from the coil to the block using a croc clip, or something like that. I have tried to replicate it but never got it to work. If the engine then runs ok you know for sure its the condensor and it will get you home.

[gingerbrick]

thanks for the, advise i got sorted. after testing absolutely everything thought i would change the condenser, as a last chance. talked to the guy at my local parts dealer and he thought it could be a cheep rotor arm earthing, it was replaced with one off ebay, original one got smashed in two.

before i fitted the condenser i thought i would try to see if the rotor arm was earthing and sure enough spark through the plastic, dug out the old one glued it back together and hay presto. i dont know if it was going through the plastic or a fine crack that developed (didn't see anything) but i do know theirs a blue performance arm (plastic rivet not not metal) on its way.

Good job i bumped into that guy, i would still be scratching my head. thats another thing to look out for, another lesson learnt. thanks again, i guise this was an odd one or is that what you meant by rotor arm failure kernow?    

[KernowCooper]

Yes mate thats exactly what I ment, I actually did a article in the FAQs on testing Rotor Arms today here http://www.theminifo...m/#entry2874407