1800: 1800E on carbs won't start!

[142 Guy]

Next in line please!

If you have a voltmeter, check the voltage at your battery + terminal while the engine is running. If the voltage is around 12 volts then your alternator is not charging. If the voltage is above 13 volts the alternator is doing its thing (13 volts being a tad low - 13.8 - 14 volts would be in the money) and your charging light illumination is caused by something other than a non working alternator. Assuming that the alternator is not working, I would be first inclined to check the connections at the back of the alternator and the connections to the voltage regulator to see if something came adrift or you have a broken wire.

I have attached the portion of the wiring diagram showing the alternator (14), regulator (17) and the charging light (21). The red trace shows the charging light circuit which is also the field flashing circuit for the alternator. The fact that the charging light is coming on means one of three things:

1) The alternator is not charging because the alternator or the voltage regulator has shuffled off this mortal coil (death can be temporary because of a loose connection inside the alternator or a one way ticket - totally mangled slip rings). Try tapping the voltage regulator case. If there is a stuck contact it may start working; however, this is normally a temporary patch.
2) There is a short circuit to ground somewhere on that red charging light circuit which causes the charging light to illuminate and prevents field flashing of the alternator.
3) The alternator is not charging because of a broken / open wire connection at the alternator or the voltage regulator.

[sleek lemur]

All great suggestions. Especially the IGN light, as ignition switch is a poor fit in the dash after....well, that's another story.... I have found a small black lead floating in mid air close to the alternator (I thought I knew every inch of this car!), but can't see any obvious home for it.

This is Groundhog Day.. when something suddenly goes wrong and unearths a years-old electrical bodge....

Ok, down to the garage now, with your list of suggestions in hand.

[sleek lemur]

Will go through you list this morning and report back.

[powen1]

Hi , I think your black wire is from the brake pressure sensor on side of wing inside engine bay, I'll send you a pic of mine via email
Cheers
Paul

[Laird Scooby]

Originally Posted by sleek lemur

I have found a small black lead floating in mid air close to the alternator (I thought I knew every inch of this car!), but can't see any obvious home for it.

Alternator earth strap by any chance?

[sleek lemur]

Rats! Shows 12.5v @ battery. Voltage regulator was replaced last year. Will Google for further tests.

Onward!

[Army]

Originally Posted by sleek lemur

Rats! Shows 12.5v @ battery. Voltage regulator was replaced last year. Will Google for further tests.

Onward!

When checking this start with your alternator - there are different types with different wiring requirements. Some alternators need a supply from the battery to initiate charging (a loose wire could be the culprit) - but don't assume check!

As the wiring loom has been changed going off "what it should be" isn't necessarily what will help.

Start from first prinicples then proceed.

[Laird Scooby]

If the car has been laid up for a while, don't discount the fact the slip rings may have corroded or oxidised so the carbon brushes aren't making good contact - you could try revving it above ~4krpm to see if it puts the alternator charge warning light out as often this can bring about a recovery for two reasons - one is residual magnetism in the rotor and it also helps clean the slip rings. Let the engine get a little bit warm first though so you're not "racing" it cold.

[Derek UK]

You didn't say if the ignition light came on when you switched the ignition on. If it doesn't come on the bulb might have gone. I think it needs to be on to complete the charge circuit. Put your meter leads across the battery and give it some revs to see if it is charging.

[sleek lemur]

Thanks guys for the suggestions. Derek, yes the red light comes on with the key as it should. Can't seem to get any charge from it, but now I read Army's response, I will check wiring again. There's still something telling me that I've disturbed something when removing the FI loom. All the more galling, as POWEN managed to remove his without trouble

Will also try the reving to 4k+. If not, I found an auto electrician in Bury St Edmunds which shows an Amazon outside his workshop on the google search !, so will take the alternator there for service.