6 replies to this topic

[NED1108]

Dear all,

 

After completing my mini extensive overhaul I can not start the mini. Following facts and info

 

998 from 1988

wiring loom not replaced

mini good condition and drive in my garage 2 years ago

 

new distributor standard 

new coil

new hot leads

Carburator cleaned and new float valve because fuel came out the overflow. 

When starting it fires but when letting the key return from start position it stop immediately.

 

When first attempting to start after a few minutes the wiring loom started melting. I noticed a small crack in the brown cable. The white/pink cable to the coil melted. I replaced the melted part. Last 4 inches to the coil.

 

Now it’s not melting anymore but I noticed that the wire is getting worm with several starting attempts.

After few attempts the spark plug get wet and black. So I have spark and fuel.

 

The big question: I tried to measure the voltage over the coil. Assuming that I would have 12v over the coil if I switch the ignition key in the position before I switch to actual start.  No voltage at all. During start I can read voltage and after releasing the key no voltage and engine stops.

 

Can someone explain what I should read in what starting sequence in relation to voltage over components. 
What could have cause wire to melt?

 

And any advice how to continue.

 

HT leads, firing order, distributor position etc all checked.

 

 

 

 

 

[lsto]

The pink and white wire to the + side of the coil is your ballast feed wire. This should go to the ignition switch and have 6-9 volts with the ignition on.
On the same terminal of the coil you should have a white and yellow wire which goes to the starter. This gives 12volts to the coil when cranking to help with starting. Once the engine is running your coil should be fed with the 6-9v from the ballast wire (pink/white).
It sounds like this wire may have failed somewhere between the coil and ignition switch. Id trace the wire and see if you can find a fault. These wires can fail and melt as they are a resistive wire which drops the 12v from the ignition to 6-9v needed at the coil. Remember these wiring looms are 40 odd years old.
You can bypass the wire by running a wire from the fuse box to the coil but it would need a ballast resistor fitted so you don't overheat your coil and melt your points. You would also have to identify a fuse that becomes live with the ignition on and run it from that. Good luck.

Edited by lsto, Today, 07:53 PM.

[NED1108]

It’s strange. I just was measuring and when I removed the white yellow wire from the coil the engine started en kept running…

 

where can I find the ballast it self?

Edited by NED1108, Today, 07:53 PM.

[lsto]

I have had weird faults in the past where my engine kept cutting out but voltage always measured ok with ignition on. It ended up being a bad earth on the battery cable in the boot where it attached to the floor. I cleaned it up and it was fine after. May be worth checking that and the earth strap on the engine steady to make sure they are in good condition.

[lsto]

It’s strange. I just was measuring and when I removed the white yellow wire from the coil the engine started en kept running…

where can I find the ballast it self?

I believe the wire itself is resistive rather than an actual resister fitted.

If you have no voltage on that wire I'd be looking for a break in it or perhaps corroded terminals in the plugs under the ignition switch.

Edited by lsto, Today, 08:04 PM.

[NED1108]

I just measured it again.

 

white / pink also reads 12 volt. This might be the issue of melting pink wire???

 

I disconnected the white yellow and it’s starts and runs perfectly.

 

But I should not read white pink 12v

 

Because the starter motor is new might it be related to the starter?

 

I will clean the negative in the back in case of. Front earth wire is new.

[lsto]

If it runs with the starter wire disconnected perhaps the starter terminal has a fault and is shorting straight to earth when the starter is disengaged, this would short out you coil and potentially cause your melting problem on your ballast wire. Sounds like you might have found your problem.