10 replies to this topic

[frog998]

Model:converted 1275
Year:B reg so guessing at 84/85
Description of problem :
My mate has been having serious problems with his mini over the last few months and various garages have just thrown parts at it, which works for a few weeks before the original fault re-appears.
The car turns over but will not fire, he has had new points, condensors and even new dizzy and plugs but still after a few weeks the fault returns, this time though he was driving when the car suddenly stalls and wont re-start. i have promised to have a look at it for him but i'm also stuck.
There appears to be 12V at the coil but there is also what appears to be a white ceramic resitor in circuit before the wire goes to the coil (some sort of ballast resistor?) any way when i 1st got the car it started and ran just fine, then it cut out and know it want restart. I have checked this resistor and think that it is shorted out (almost a dead short) but also heard about how the ignition switches are prone to failing. Dont really want to spend anymore of my mates money without being totally sure of what the fault is or might be so any help or advice would be welcome.
I have tried and checked the coil by fitting an old (proven) coil that i have but there is no spark. I have tried checking the wiring with my haynes manaul but who ever changed the engine has cut and spliced that many wires that nothing corresponds to the schematics.
If i run a direct 12V to the coil would this allow the car to start just so i can prove that it is either this resistor (which i looked for on Minispares website and it costs £18 and is listed as a turbo fuel pump reisitor) or that the ignition switch its self is the problem.

Have spoken to my mate (who towed it round to mine) and he said that on the way round he got it started ny bumping it but as some as it started it cut out again

Edited by frog998, 05 September 2008 - 01:44 PM.

[frog998]

Just measured the Ohms across the coils terminals and they read 1.3'ish so it should be a ballast'ed ignition. Are (whoever re-wired the car) using the resistor (http://www.minispare....aspx?pid=33476) to drop the voltage for the coil. Would i be better either fitting this (http://www.minispare....aspx?pid=34434) or would it be easier to fit a 12V Non ballast coil and run a new 12V supply direct from the No1 fuse to the coil?

Edited by frog998, 05 September 2008 - 03:39 PM.

[dklawson]

As part of your troubleshooting, I would actually recommend that before you run out and even make any of the voltage measurements I list below... check the points. Make sure they are clean, dressed flat, and adjusted properly. Make sure the plastic heel block on the moving arm of the points has a little thin grease (Vaseline) on it as does the square lobe came in the dizzy. Points in Minis have a tendency to close up prematurely... particularly the parts that seem to be available now. Again, check the points first before even making the voltage measurements I recommend below.

Your measurement of the coil resistance should have been performed with the low-tension wires removed from the coil. If you make that measurement again (w/o wires) and still get 1.3 Ohms it would confirm that the car has a ballast coil. The resistor should be in series with the power from the ignition switch. Hook the low tension wires up again, open the distributor and place a coin between the points. Switch on the ignition and use your meter to measure the voltage between the following points 1) Measure the voltage between the supply (ignition switch side) of the resistor and an earthing point. 2) Measure the voltage between the low (coil side) of the resistor and an earthing point, and 3) Measure the voltage across the coil's low tension terminals. Again, all these are done with the coin between the contacts and the ignition switch in the run position. Let us know what you found as they will confirm what power is coming to the coil and what the resistor is doing.

Chances are that the person who fitted the ballast resistor because the car originally had a standard ignition. The wire supplying a standard coil will be white. A ballast resistor wire from the ignition switch will be "pinkish". If your voltage tests above confirm 12V on the supply side of the resistor and the wire is white, you'd be fine getting a normal (12V) coil and removing the ballast resistor and ballast coil. However, this may not address the problem.

You're saying that the car is hard to start and that a ballast coil and resistor have been fitted. To take advantage of these you really want a 4-terminal starter solenoid. The 4th terminal of the solenoid supports a small wire that runs from the solenoid to the coil (+) terminal. This allows the coil to produce a hotter spark for starting the engine while you operate the starter.

Get back to us with your tests results, but please don't spend money on alternate coils if the coil is actually making a decent spark. For more help on general troubleshooting of the ignition system, please download my PDF and perhaps work your way through its troubleshooting section.
http://home.mindspri...tsIgnitions.pdf

[frog998]

Right. managed to get 1/2 hour between rain so, 1.3 ohms across the coil terminals - Ballast coil,
12 Volts at the 1 side of the ballast resistor but only 4.5 at the other side (think resistor is to strong or knackered).
Tried to start the car with a direct 12V placed onto the coil and still nothing, got the wife to try and start the car with the dizzy cap still off and no sparks accross the points. Removed the centre HT leads and held this to earth no sparks.
Think there might be a number of faults.

Where do i go next?
Swap the coil for a Non-ballast 1 or buy a new resistor? Until i can get the correct voltage at the coil is it worth trying anything else?

[stormintrooper]

just hoping sum1 will clarify this for me, iv looked at haynes manual and it says both my white/pink and white/yellow wire shud be going to the + of the coil, is this right, and yes i have ballasted system and coil, also how does one check for spark as haynes doesnt make it clear (for us dumb folk)

[frog998]

To test for a spark, remove any of the spark plugs and with the HT lead stil on the plug, hold the plug so that the bent bit is touching an earth point (i usually position the plug by hold the lead with a pair of insulated pliers). Get someone to try and start the car and you will see a spark jump across the plug

[dklawson]

Where you go next, how to check for spark, and general troubleshooting of points ignitions is in the PDF I posted the link to. Please give it a read. In the opening section I try to explain how the system works. If you know what's supposed to be happening you'll understand better what your test results mean.

When you hook full 12V directly up to the coil as you mentioned earlier... only do this while starting the engine. Do not leave it like this. If you run a ballast coil on a full 12V supply you will pass too much current. This in turn will damage the points and eventually cause other components (including the coil) to fail. The ballast resistor is there for a reason.

The yellow/white wire mentioned is used on ballast ignition systems. It runs from the 4th terminal on the solenoid up to the coil (+) terminal. It provides full system voltage to the coil while the starter is operating.

Again, please look over the PDF and as I mentioned in my first post, since you're measuring voltage drops, you know current is flowing through the ignition system. Therefore, make sure the points are actually gapped right before you do anything else.

[frog998]

My mate had a new / second hand dizzy fitted by a garage and like i siad it ran for a week or 2 then died hence why i now have it (to try and save him some money).
I've read your PDF and have tried most things on there (not easy when your depending on the wife to crank the car over While looking after our 3 year old daughter!)
Who ever converted from a 1000 to a 1275 used the existing starter motor (no external solenoid) and for some strange reason this has a wire going to the - side of the coil (should this be to the positive side to give the Hot spark on cranking?).
Only had 30 mins or so between rain showers so only tried the basics

[dklawson]

I've read your PDF and have tried most things on there (not easy when your depending on the wife to crank the car over While looking after our 3 year old daughter!)

Who ever converted from a 1000 to a 1275 used the existing starter motor (no external solenoid) and for some strange reason this has a wire going to the - side of the coil (should this be to the positive side to give the Hot spark on cranking?).
Only had 30 mins or so between rain showers so only tried the basics

I can completely relate to the kid issue. Mine are older now but it was very difficult when they were the age of your daughter. Hang in there, it does get better.

For future reference, there should be a spade lug on the solenoid with a white/red wire. With the ignition switch on you can use a small jumper wire between the battery feed cable on the solenoid and the lug with the white red wire. When the jumper is held against the white/red wire lug the engine will turn over on the starter.

You say there is a wire between the solenoid and the coil (-) terminal... the terminal that is connected to the distributor by the white/black wire? If I understand that correctly... oh boy! You're lucky something hasn't melted and I don't see how there could be any spark at all. Remove that wire at the coil and cover its terminal with electrical tape and try again. If that wire is feeding battery voltage to the coil (-) terminal it will be creating the situation where both sides of the coil are at the same voltage... which means you cannot generate a spark at all.

[frog998]

Thanks for all the help.
The problem turned out to be a faulty condensor, £4.49 and a good battery charge and alls well.

[dklawson]

Excellent! I'm glad you sorted it and found an inexpensive fix for your friend. He should treat you and your family to a nice dinner!