ignition works fine when engine cold then no spark when warmed up?? help!

[contessaman]

here's a plea to those with kowledge of older petrol engines. I'm trying to help my father in law with his little thames river boat but alas my knowledge is limited to yachts and diesel engines.

engine is a watermota sea wolf which is a marinised ford 1100cc crossflow engine. it has ignition pretty much as per a mk1 ford escort other than last year he had one of these kits fitted which replaced the condensor and points with a little red box and an electromagnet. the engine was running great when the boat was put ashore for the winter.

now the engine starts fine when cold and runs beautifully for about 20 mins then goes put put and stops. he has one of these inline things with a neon light and we can see at this stage there is no spark. obviously with no spark it then wont start. walk to pub have a beer and let it cool down. starts and runs fine for another 20 mins. repeat.

I put a new coil on because I thought perhaps it had a break in it that appeared when warm. still the same. any other ideas??????

thanks!

 

[greenalien]

The 'little red box' is a CDI (Capacitive Discharge Ignition) unit - the problem could be insufficiently thick wiring to the unit, resulting in the capacitor not getting a full charge - or the CDI unit could be faulty. Try Googling 'CDI ignition troubleshooting' for more info.

 

[charles_reed]

here's a plea to those with kowledge of older petrol engines. I'm trying to help my father in law with his little thames river boat but alas my knowledge is limited to yachts and diesel engines.

engine is a watermota sea wolf which is a marinised ford 1100cc crossflow engine. it has ignition pretty much as per a mk1 ford escort other than last year he had one of these kits fitted which replaced the condensor and points with a little red box and an electromagnet. the engine was running great when the boat was put ashore for the winter.

now the engine starts fine when cold and runs beautifully for about 20 mins then goes put put and stops. he has one of these inline things with a neon light and we can see at this stage there is no spark. obviously with no spark it then wont start. walk to pub have a beer and let it cool down. starts and runs fine for another 20 mins. repeat.

I put a new coil on because I thought perhaps it had a break in it that appeared when warm. still the same. any other ideas??????

thanks!

Sounds like an ideal "force majeure" incident demanding a (increasingly voluptuous) series of 20' hops from one riverside pub to the next.

 

[contessaman]

The 'little red box' is a CDI (Capacitive Discharge Ignition) unit - the problem could be insufficiently thick wiring to the unit, resulting in the capacitor not getting a full charge - or the CDI unit could be faulty. Try Googling 'CDI ignition troubleshooting' for more info.

its one of these:

http://www.accuspark.co.uk/accuspark.html

im not sure that its what you think. I thought it still used the coil to generate the HT not a capacitor and it just uses a rotating magnet and a reed switch with a transistor to provide the interupted LT current that would have been provided by the points.

The provided gauge of wiring was used when installed and the fact that it ran fine all last season leads me to believe that its probably not an issue with the 12vdc wiring between the unit and the coil. I have tested the wires with my meter on ohms and the circuit is good.

of course the unit itself could be defective with some hairline crack that rears its ugly head when hot but I ws hoping there might be something else I can try before just replacing the red box as part of trial and error fault finding. Its getting expensive! damned thing.

I do wish he had a nice little diesel on the thing! still, when my engine doesn't start I either have to fix it at sea or find somewhere like barry or milford on the bristol channel that can be entered under sail. when his doesn't start he drifts into the river bank, finds a pub and takes a pipe while he thinks about it. its certainly a different approach to boating!

 

[contessaman]

Sounds like an ideal "force majeure" incident demanding a (increasingly voluptuous) series of 20' hops from one riverside pub to the next.

busted! would have gotten away with it too if it wasnt for those pesky kids....

no really I can assure you there has been no sabbotage!!

 

[nigelmercier]

last year he had one of these kits fitted which replaced the condensor and points with a little red box and an electromagnet...

Do you still have the points and condenser? You could try putting them back.

 

[VicS]

Do you still have the points and condenser? You could try putting them back.

Absolutely.

First thing I do would be to convert back to a conventional ignition system.

I had a neighbour and colleague at one time who had fitted some such kit to his Mk 1 escort. After replacing it a couple of times he eventually gave up with it altogether

 

[nigelmercier]

Absolutely.

I'm always pleased when Vic agrees with me, it means I wasn't talking bollox

 

[Iliade]

Sounds likely that the coil is playing up. I recall having had similar problems with old cars & bikes.

 

[contessaman]

Sounds likely that the coil is playing up. I recall having had similar problems with old cars & bikes.

but the coil was replaced

 

[contessaman]

Do you still have the points and condenser? You could try putting them back.

thing is, we went to this breakerless ignition because condensers and points werent lasting any time at all. chatting to an old boy in the village motorfactors, he believed the problem is - nobody needs them any more, so the only ones you can buy now are made in china and of such poor quality some are broken striaght out of the obx. to be fair they cost almost as much as the electronic unit anyway- thats about £35 so I think we will be just as well to try a new one of those.

the only points and condensors that seem to last are old stock ones found on a dusty shelf in a motor factors. these tend to be lucas or wipac and they actually last a season.

the more I think about it- the more it must be the elec ignition unit. theres not anything else to go wrong is there!? it just goes completey dead, no spark at all. HT leads were new last year too. now the coil replaced. must be that little red box....

 

[Alpha22]

but the coil was replaced

With one that was also faulty...... ???? Not impossible.

 

[nigelmercier]

Do you still have the points and condenser? You could try putting them back.

we went to this breakerless ignition because condensers and points werent lasting any time at all. ... must be that little red box....

I meant as a fault-finding exercise, to prove it is the red box.

 

[johnlilley]

Don't forget ignition leads, if the one from the coil to the distributor has failed then all will fail. Years ago the manufacturers changed from using solid wire leads to carbon impregnated leads which had a finite life & often did fail when the lead warmed up. Also caused missing. The longest lead failed first, followed by the others.

John Lilley

 

[Dino42]

As well as the leads I would also change the plugs and distributer cap if you haven't already.

 

[LittleSister]

First thing I do would be to convert back to a conventional ignition system.

Sounds likely that the coil is playing up.

but the coil was replaced

With one that was also faulty...... ???? Not impossible.

Don't forget ignition leads

As well as the leads I would also change the plugs and distributer cap if you haven't already.

Probably best to replace the battery, carburettor, engine and gearbox, too, just to be sure! ;-)

 

[rustybarge]

The transistorised ignition has an overload cutout built in to it, to stop the output transistor blowing up.

Locate the gubbins to a place where it will run cooler.............

 

[William_H]

Another option which may appeal to the OP is that you can buy from an electronics supplier freeze in a pressure can. When sprayed onto electronic components it reduces the temp dramatically so you can cool each component to see which one is faulty when it starts working again.
It does appear that this ignition unit simply replaces points with inductive pick up and transistor to switch current through coil.
Capacitive discharge ignition is similar but discharges a capacitor charged to about 250vdc into the primary of the coil giving a much higher voltage and an ability to operate at very high rates. (high RPM on 8cyl cars) good luck olewill

 

[grumpy_o_g]

It does sound like a case for the freeze spray. I had exactly the same symptoms on a Morris 1100 a thousand years ago and it was caused by the condenser (capacitor) inside the distributor breaking down as the temperature rose. That's looks to have been replaced but electronics does have a habit of stopping working as it gets hot, capacitors especially. If it's just cutting out completely all at once then the overheat cut out looks a possibility. If it's spluttering a fair bit then it's most likely an electronic component gradually failing as the temp rises. Squirt some freeze spray around (making sure you've got the non-flammable one) and see what happens. The effect is often almost instantaneous.

 

[Gymnopedie]

Sounded like the condenser failure I experienced on my BSA Bantam years ago; but as no points/condenser I would put money (someone else's) on the distributor cap. I had a marinised Ford in a motor cruiser (inland waterways) in the 70s which exhibited similar symptoms. Changed everything on the HT elecs side leaving the d.c. until last. It turned out a hairline crack was with oil in it was causing earthing when hot.