Tacho/ fuel guage on S4

[tyasman]

It looks like I will have to take out and repair the rev. counter on my 1970 Elan S4. It is either not working at all or bounces all over the dial. Sometimes when on steady revs it seems fine. I have had the electrics fully and professionally tested, and I'm told the fault is on the "positive" side, ie between the tacho and the ignition. I've also developed a fault with the fuel guage which occasionally moves to "full", then returns to its proper position. Could the two be linked? What work is involved in taking out the tacho and either mending or replacing it? Thanks for any replies.

[steveww]

Ship it off to Speedy Cables for a heart transplant

[ppnelan]

Re: fuel gauge problem - have you checked the tank sender unit, and maybe the voltage stabiliser

Re: rev counter problem - do you have electronic ignition? If so, what type? The rev counter can be highly sensitive to different types of electronic ignition, and also to where the feed to the ignition coil comes from. Mine has Lucas electronic ignition. I tested it yesterday with an additional feed from the ignition switch supply on the fuse box, in parallel with the feed through the rev counter. It reads more accurately than before (used to read high), but bounces wildly with the flasher unit switching on/off, and anything else that gets switched on or off! Probably a dodgy cable or connection somewhere in the (original) loom, or could be an earth problem - they usually are...

A previous thread mentioned replacing capacitors in the rev counter which fail with these symptoms with old age & heat...

Matthew

[neilsjuke]

Check the bullet blocks near the ign /switch /towards the heater (green /white wires) also the glove box switch and the earths to the revcounter all using bullet conectors i would replace them all with brass solder bullets and new coectors ( you can clean the conectors in a shot bead cabnet) or use switch cleaner etc.
Neil