Major starting fault - very strange

[Maser4200]

Hi All
I bought a Eunos last August and am totally smitten with it. A bit scruffy and a few squeeks and knocks but seriously good fun blatting around the lanes - get a cheesy grin everytime I go out. I don't do many miles look after the basics and the car until the other day has looked after me.
I fired it up and moved it out of the garage to do some work on the paint (polish and elbow grease). When I went to put it away I turned the key - the engine turned over for a split second then ABSOLUTELY everything died. Gave it a minute and the 'alarm' light started to flash again but nowt when the key was turned - back to dead. So, pushed it back in - and using the battery isolator that I fitted a few months ago to the battery 'disconnected the battery'.
Came out next day, reconnected through the isolator and hey presto power. Worked various switches; Side lights came on, main head lights jumped up and dash lights showed all systems 'go' - shouted 'stand clear'....turned the key to start and......nothing. Everything died again. Key off wait a few minutes - nothing. Isolated battery - gave it a few minutes and....nothing.
Have checked some of the obvious points like grounding strap, battery connections etc but no luck.
Anyone have any ideas out there in MX 5 land? Want to get it back up and running so I can take advantage of the next sunny day (guess I have some time to fix it...but you never know - got to be ready to roll)
Many thanks for all thoughts and advise.
Regards
Maser4200

[Setch993]

Hi
I have had exactly the same, I suspected the battery had expired to zero volts in a split second I removed the battery (non standard MX5), charged it on my Ctec which said it was fully charged, refitted it, making sure the battery leads were spotless and tight. Car started instantly on turn of key and has been perfect ever since
I concluded it was a battery lead/battery connection ?
Agree with you, big grin every time I drive it and for a relatively low investment

[NiceCupOfTea]

If things are working until a big draw of current that could suggest a duff battery connection. I had similar in mine a few years back - turned out that the non-standard battery had been shifting in the boot and broke the earth strap. Worth a check.

Otherwise, could be ignition key switch?

[BruceBogtrotter]

Immobiliser?

[mad4amanda]

Its a known fault in the mx5 community its the ignition barrel being pulled down by a wheighty key ring either now or in the past . run with fewer keys and push it in hard and it should work better when it gets too bad find another ign switch.

[Maser4200]

Thank you for all suggestions - will get into it Saturday morning and report back.
Cheers
Maser4200

[NeoVR]

As above it does sound like a dodgy earth strap.

Also check the grounding point connecting to the back of the PPF near the diff.

[Maser4200]

HUGE thanks for advice. Car is running like a trooper again. Pulled the battery out (the positive connection was not as tight as it might be) - while I charged it went through everything under the dash......put it all back together and fired up first try!!! Cheesy grin back!
To celebrate installed a new radiator - only a twenty minute job. The car is such a pleasure to work on - designers seemed to have thought things through. (I race a Porsche 924 and even though it's stripped to the bone you need extra joints to reach a lot of the stuff)
Really appreciate all of the advice.
Thanks again.
Cheers
Maser4200

[NiceCupOfTea]