Lotus electrical nightmare of all nightmares...another one..

[omendata]

The rev counter works fine.

If the igntion amp was faulty wouldnt the engine fail to start on either position of the igntion?

I think my father has just wasted £40 on a new amp!
Everything hinges on the fact that he is not sure whether he wired the coil back up properly as he didnt take note of where the connections went before he removed them.

12V and 1.25v connections on +ve
The remaining two which are harnessed together to the -ve

I am working on the old technicians first question "what was the last thing you changed before things went wrong".
Bearing in mind my father has a habit of fiddling with things and causing all manner of problems - the last time he overfilled the oil reservoir and the car developed a nasty startup problem!

[Markexel]

The rev counter works fine ,but thats where those extra coil wires go to

If the amp was faulty id say u wouldnt get a spark so it will never start,so yes u are probably wasting ur money

[omendata]

Well from what i an gather he had problems with the new coil as the car wouldnt start at all
So he put the old coil back in and it started

The engine runs fine as long as the key is in the top position but that means you have to have a very strong hand and driving one handed isnt recommended in the highway code!

It will probably all come down to a faulty wire or bad earth or summat like that but ill find it now if it kills me!

Thanks for your patience guys - Ill deffo give the solution once i find it as you must all be thinkin this Lotus has a ghostus in the machine!

It certainly has cost a fair penny - I dont think many people would be willing to shell out £1500 for a service on a £4500 car!

I must admit im no Lotus expert (can you no tell) but it does seem that these cars have been built out of the parts from many other cars cobbled together. I have replaced the front fan Fiesta , Bonnet Strut - Volkswagen etc etc etc

The term Lots Of Trouble Usually Serious does seem quite apt but my mother loves her Lotus to bits and will not part with it- literally!
It is a headturner although ive always preferred the Lotus Esprit SII (White) myself but then I was always a James Bond fan!!!
Pity they arent as waterproof as Mr Bond suggested!

I hope I can get it sorted in time for the Callander event!

[Markexel]

Dont know if i should sujest this ,but try putting the wires to the coil the other way round

As for the rev counter ,they work by gettin the pulse signal direct from the coil thats what the extra wires a for

[omendata]

Tried every combination of the coil wires - nada

Im running out of ideas hence why im on here!
I think i may be a permanent resident!

[omendata]

I didnt realise you needed a special coil for electronic igntion - arent they all the same?

The car wouldnt start at all if there wasnt a spark or am i missing something?
In answer to the question of why the starter motor doesnt engage once the engine is started you need to know the difference between the older inertia starter motor and the pre-n type..

The pre-engaged starter does what it says. It engages the drive gear into the ring gear prior to the motor itself spinning up. On the whole this prevents wear to either of the gears.

To achieve this a solenoid is mounted above the starter.
When the starter is switched the solenoid pulls a plunger into itself. The plunger is connected to an engaging lever that in turn is connected to the starter gear. So switching the starter pulls a plunger in which pushes the drive out into the ring gear.

At the top of the solenoid are a set of 3 contacts. One comes from the battery, one goes to the starter motor itself and between them is a moving contact. The plunger (which I talked about in the previous paragraph) comes back and pushes the moving contact onto the others, thereby connecting the battery to the starter motor.

So the motor now turns, however as the drive is now engaged in the ring gear before the motor spins, it doesn’t wear out the gears.

On pre-engaged starters the drive has an internal one-way clutch. This slips in one direction and locks up in the other. This is again designed to prevent the starter running with the engine as it helps to stop over-speeding, because when the ring gear is going faster the drive it slips.

I hope that answers your question - Being an older car i believe the Lotus Excel uses the inertia type but some have had pre-n types fitted i can only assume like ours!

My Dutton kit car being a Xflow engine used to use the inertia type but it is prone to jamming in the flywheel (a common starter motor problem on older cars) as well as mashing up the barrel and pinion teeth so i replaced it with a Capri pre-n which works fine!

[16VJay]

Hi Omendata,

You don't say how old your Mum's Excel is - if it is an older one it will have the old Triumph type ignition switch which from your description of the key positions sounds likely.

I had the same item on my Elite and it developed exactly the same fault.

The cause was the lobe on the back of the igniton lock wearing the plastic socket it located into on the electrical switch that controls the ignition. There was just enough slack so that when the key returned to the run position the switch was moving slightly further and shutting off the ignition.

If your Mum's Excel's ignition key is in the edge of the dash beside the steering column then you have this Triumph ignition switch. If the key's in the column you have the later Toyota bit - you may still have the same fault.

To remove the Triumph switch, reach up under the dash, pull the concial cover off the back of the switch - this will either pull the electrical switch with it, or if it just slides up the loom, pull the switch off the back of the ignition lock. Make a note of the wiring positions, take off the wires and try the dealers for a replacement. If you have trouble, it's the same part as on a pre-1975 Scimitar GTE

HTH,

Jeremy.

[Steve C]

Another idea ...

I don't have my Excel manual to hand so I'm not sure if this is valid, but a lot of cars have ballasted ignition coils. This means that there is a resistor in series with the power feed to the coil. When in "start" position, the ballast is bypassed to give the coil the full 10v or so present when cranking, when the car fires and the ignition is released to the "run" position, the ballast resistor is in series with the power feed to the coil.

So .. like others have said, it could be the ignition switch in the "run" position, or, *if* a ballast resistor is fitted, it could be that resistor or wiring to it.

What voltage is at the coil in the "run" position?

[omendata]

Yip ballast resistor - is it easy to get to?
I wish i had a manual!
May well be what the problem is but 16vjay it is exactly the same ignition switch so ill test that too!

Well at least I have a couple of other things to try this weekend!

[amarshall]

If it's a Triumph type ignition switch and you need a new one - try Rimmer Brothers (see the recommended suppliers thread )

[Redexcel]

The manual says (page 28, section MA) that the Lucas constant energy ignition system coil requires no ballast. So it can't be that !!

[omendata]

Good so then it really does come down to one thing and thats the ignition barrel.

I'm pretty sure the new amplifier wont make a difference but it was what the electrician was going to change!

We shall see!
Now I have the manual should make things much more easy!

Cheers!

[Danny]

Hi, I agree with the postings that if the engine turns over and runs in the with the key in the start position, but stops when you release it to the run position that the amp should be ok.What I would check first is that when the key is in the run position that you are getting 12v at the coil, if this is not so then check the wiring back to the ignition barrell and as a check bypass the run position on the switch but ensure that you can kill the bypass when you want to turn it off
Regards Dan

[omendata]

From what my father told me there is 12v at the coil in the run position
which is what has made this all the more bizarre.

He also bypassed the ignitio barrel by wiring the battery +ve directly to the coil.

We shall see tomorrow!

[Danny]

Just a wild thought, has the car got an aftermarket immobiliser or allarm that could be causing problems, had a car that had one and it caused running problems until it was removed.
Regards Dan