EEK

Is that the actual excitation current? I think the real excitation current is fed via the regulator pack and the current fed is dependent on the voltage read from the warning light circuit. At least that is my understanding.

Try these guys perhaps, http://www.bikerhouse.com/testsite/minister2011/r500_service_centre.php

OK - whilst not on a K series and therefore may not be relevant but I had fuel pump stop on my HPC, The problem was in a large Eco seal connector in the engine bay, about 12 wires in it one of which was feeding the fuel pump. On opening connector there was clear overheating occurring on this connection, once cleaned all OK. So I guess I am saying are you sure there are no other connectors between MFRU and pump that might have been overlooked?

Dirty contacts in the MFRU?

Well, once spring is removed, if you stand on it how much does it go down by? In that the rating, is required weight to compress the spring by 1 inch, well according to this it is https://www.knowyourparts.com/technical-resources/suspension/springs-and-suspenstion/

Plastic bag over the oiled sausage if the car is left in the open and rain is forecast overnight, the bonnet, being a tight fit around the sausage holds in in place. Running in the wet not a problem, I suspect by the time any collected water on the sausage has been hit by the rush of air into the cylinders it is vapour and as, in rain, normal air has a pretty high humidity, then don't think it will realistically but any different to running in normal wet weather. Also by product of combusting that petrol is water so not really that much out of the ordinary.

to remind you - IMHO rear fogs when on in absence of fog, PITA at night less so in the day

Try driving the cable with an electric drill when disconnected from the right angle drive, if OK then try with the right angle added to cable etc.

My understanding, +ve supply to one side of light, that then goes to earth via the alternator, so the light comes on, once engine running and voltage from alternator increases then affectively the earthing is switched off by the produced voltage. So if the issue is a vibration or something causing an effective earth of the light and reason it comes on, then if the wire from the light to the alternator is disconnected at the alternator then light won't work but once engine is at 5,000 light should come on. If it doesn't then suggests something in the alternator regulator pack is not quite right.

@ John Vine - no I had an analogue gauge from my Lotus Twin cam Dutton miss spent youth for TDC :-)

I used these https://www.chronos.ltd.uk/product/electronic-digital-dial-gauge/

Try this one, https://www.lotus7.club/forum/chitchat/mirror-mounts

I recently had fuel pump stop working, not CSR but S3, just happened when I went to fill with fuel, but it was 12.00 and it was. France so I guess car wanted a lunch break. Anyway I was able to send 12v down the wire to the pump from a connector block in the engine bay. The pump worked, so was able to quickly rule pump out. I could equally have done it from the relay i.e. take relay out and push 12v live into the wire from relay holder. In the end it turned out to be a compromised (high resistance) connection in the engine bay plug. Quick scrape and refitte, on my way again at 13.00, so was just a request from car for lunch break :-) Been fine ever since.

My experience on this issue is: Rear carbon fiber wings going milky, so used some spray wax in a yellow can, readily available from UK supermarket. Recommendation came from this forum, that was about three years ago. It made it better and I used it for about a year. Then they started getting milky again and it was just getting worse and worse. After a wet day in the Dolomites last year they were more white than black. Decided to bite the bullet, loads of solvent including acetone used to remove, I hoped, any residual wax. Sprayed them with a 2K Clear coat with the intention of then protecting them with some clear film. Unfortunately or fortunately, before the film was applied came across a chap with a green R500 so went for a blat. The 2K got chipped and then I realised it really hadn't bonded and was able to pull it all off in great big pieces, all except the bit that was under the rear light cluster. So I guess it was related to the previous treatments. So having removed all that first application of 2K I sanded the wings down with 120 then 220 grit on DA sander, then did it again. This seems to have bonded fine, in that again film did not get applied and it chipped but did not peel off. So that then needed to be sanded down again to remove the chips then re sprayed and film applied. For now they look fine but not been out in the wet to test the edge bonding question. All good spraying practice!

My understanding is that in"modern" alternators the ignition light gets +ve feed which is earthed via the alternator, this is the sense wire that "feeds" the alternator regulator. The sensed voltage determines how much current to feed to the rotor, controlled by the regulator, and thus the magnetic field strength of the rotor. The strength of this magnetic field determines how much current the stator produces and sends to the rectifier assembly and thus the output current at B+ I say "modern" because being as it is a cross flow not sure how old alternator is and if the technology has changed. I currently have a couple of alternators off my 1994 Defender in pieces so fairly well versed on issue around that vintage. My sense wire is brown/yellow stripe but that is NOT on the Caterham, that being said on the Caterham there is a brown /yellow so some consistency

Think I found all the answers here: https://www.lotus7.club/forum/techtalk/wilwood-265mm-and-hi-spec-260mm-discs-easy-acquire

Mike - thanks for this - challenge is I'm in France and car is in UK and was hoping to get them to fit when next over in case it's raining and I am stuck in the garage. I have the drawing from HiSpec so perhaps will measure this next time and get them for the time after. I am sort of guessing that the design of their caliper allows for the bigger disc while fitting in the same overall dimensions of standard fitment.Caterham-260x10-UL-lug.pdf

Anybody aware of any potential issues in fitting Hispec 260mm solid discs along with their Ultralite 4 Caliper to an S3 (1998) shod with either 13 or 14 inch wheels? i.e. Any clearance issues?

Saw one last year, dark grey Swiss plates up near La Rosiere, will keep an eye out for it if it passes. If you need a coffee stop and a "7 tyre kick" I am in Grasse area

MAP is showing no vacuum - is that OK for such a low throttle opening?

That's easy "alcool a bruler" - next to the acetone and hydrochloric acid and before the "alcool menager"

@Jonathan - Interesting view on acetone - totally agree it can cause all sorts of damage to paint and plastic but living in France and it being something every supermarket has on its shelves (alongside the hydrochloric acid) then I tend to view it a little more benignly. I reckon useful to have easy access to something that really works!

If not lacquered, amongst the solvents you have tried was acetone include, it usually softens most glues.

You may not have no oil pressure - you may have a gauge indicating no oil pressure given you have two other probable electrical problems

A possible common/standard use of orange/white and orange/black is in the area of wiper motor connectivity for the parking functionality see https://www.autoelectricsupplies.co.uk/cms/files/colour_code_for_vehicle_wiring_-_new_order_2.pdf