12 replies to this topic

[stormintrooper]

basically, got the engine back in today and hooked up the wiring too, we then found out that my pink ballast wire was runnin at 12V and not 9V and the cranking bypass from the starter was giving 9V not 12V so making the coil plus 12V at normal runnin position and 9V at cranking position

then we found that there wasnt even any spark coming from the coil whatsoever so after all my hard work today am a lil annoyed......anyone have any ideas?

[gumball]

Che ck if there is a RESISTOR in line on the pink wire...??

i found this problem once..

[stormintrooper]

where is the resistor though as the pink wire disapears into the loom

an still dnt explain why the cranking bypass what the starter kicks out is 9V not 12V

Edited by stormintrooper, 26 April 2009 - 09:35 PM.

[Nightrain]

Che ck if there is a RESISTOR in line on the pink wire...??

i found this problem once..

LOL the White/Pink wire is the Resistor !

[Dan]

Was the coil connected when you measured the voltage at the ballast? It only works when all the components are fitted.

The cranking bypass is very unlikely ever to read a full 12v, that's the whole point of why ballasting was invented.

[stormintrooper]

i thought the idea was that it ran normaly at 9V as thats what ballast coils run at isnt it? hence the point of the ballast wire as its been reduced to 9V with the resistance of the wire
and that the cranking supply gave it the 12V to boost the spark power?

Edited by stormintrooper, 26 April 2009 - 10:14 PM.

[Dan]

That's what a lot of people think, doesn't make it true!

Ballast coils run at 6 or 9 volts in different cars. The way a ballast resistor works is by balancing the resistance of the coil itself (which changes depending on if the coil is actually doing anything or not as it's an inductive component). If you just measure the voltage at the end of the resistor while it isn't connected to anything you aren't getting the whole picture. You need to measure the voltage at that node while the coil is connected to read the static voltage and while the engine is running to measure the running voltage. The resistor does drop the voltage but it only works in conjunction with the resistance of the coil itself.

The reason ballasting is fitted is because while you are cranking the starter, due to the balance of internal resistances the voltage available from the battery isn't 12v. It's usually about 9v or as low as 6 in the winter (when the battery is suffering and the oil is thick). So if you use a 12v coil it doesn't work very well while cranking, if you use a 6 or 9 volt coil it will work far better. But it will melt as soon as the starter stops spinning and the charging circuit output climbs to 14v. The ballast is added to prevent this, the cranking bypass simply takes the ballast out of the system during cranking because if you left it in place you would still have the undervolt problem. In good conditions the starter doesn't hit the battery so hard and so the voltage will drop less and in those circumstances the coil does get a bit of a boost from the bypass but there will never be a full 12v available while the starter is turning the engine. Unless you have a geared, low current starter.

[dklawson]

Just to add to what Dan's said (and Stormintrooper... I'm sure you know this already), to measure the voltage at the coil low-tension terminals, you need to make sure the points are CLOSED. If the points are open, everything you use your meter on will measure battery voltage (nominally 12.5V). Current has to be flowing through the coil (and ballast resistor) to give you good readings. You can either bump the engine over until the points are closed... or temporarily stuff a coin between the points while you measure the coil voltage.

[stormintrooper]

hmmm ok when the wheather is dry i will have a look at this

any idea about the no spark? i did turn the engine over to make sure the contacts opened and closed fine and they do as i took off the dizzy cap to check, i held a plug against the block to check, no spark, the coil had the 2 plus LT wires going to it, the negative had one white/black wire going to it. now i soon realised that theres ment to be 2 wires going to the negative, one for the tacho and one from the dizzy but there was only two of these white/black wires coming out of the loom, now i havent changed any of the wiring in that part of the loom since taking engine out and it used to run so im confused about whats happened.

shall i just find out which one goes to the tacho and connect that and then run my own wire from the dizzy to the negative on the coil?

[Dan]

There will be two white/black cables exiting the loom by the coil (assuming the car is wired for a tacho, you haven't said what year it is) and both of these should be connected to the coil. The third white/black, which is the other end of one of the two at the coil, exits the loom a little further along and should be connected to the dizzy LT cable. The three white/black cables don't emerge in the same place so if you have two together, connect them both up.

[Cooperman]

AAAAhhhh, the 'Pink' wire.
I had a Mini 30 in with the pink wire burned out. It also took most of the adjacent loom with it and 5 hours work to re-wire it. The loom was a mass of melted plastic from bulkhead to front panel and i had to make up a new loom insert with bulet conectors on eac end for each individual wire. With a new 12 volt coil it was a £150 job.!
My advice, for what it's worth, is cut the pink wire out and replace it with a nice piece of white ignition wire, fit a 12 volt coil and eliminate the risk of a burned-out loom. Just feed the new wire from the ignition switch to the coil and tie the wire back to the existing loom. Cut the pink wire at each end and leave it in-situ.

[dklawson]

any idea about the no spark? i did turn the engine over to make sure the contacts opened and closed fine and they do as i took off the dizzy cap to check, i held a plug against the block to check, no spark,

This is not meant to sound cute. In your excitement to check that the points were opening, did you remember to put the cap BACK on the dizzy once you saw you had sparking across the points? Also, was the rotor in the dizzy at the time?

If you don't find something obvious at fault, take a read through the PDF I have on points ignitions. There is a troubleshooting section in it. You may just need to work through the system point by point until you determine why/where you are loosing the spark.
http://home.mindspri...tsIgnitions.pdf

[stormintrooper]

any idea about the no spark? i did turn the engine over to make sure the contacts opened and closed fine and they do as i took off the dizzy cap to check, i held a plug against the block to check, no spark,

This is not meant to sound cute. In your excitement to check that the points were opening, did you remember to put the cap BACK on the dizzy once you saw you had sparking across the points? Also, was the rotor in the dizzy at the time?

If you don't find something obvious at fault, take a read through the PDF I have on points ignitions. There is a troubleshooting section in it. You may just need to work through the system point by point until you determine why/where you are loosing the spark.
http://home.mindspri...tsIgnitions.pdf

a fair comment as i have seen some people on here like hmm..err...

i took the cap off after finding no sparks to check contact operation


dan..this makes alot of sense to me now as i only found 2 white/black wires..maybe the other 3rd one is hiding within the mess of headlight wires, it was starting to get a little dark so could have easily missed it