MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - ignition problem?

driving along nicely when engine suddenly cut out, tacho immediately went to zero and fuel gauge dropped to zero also. After a couple of minutes, car started but then cut out a few seconds later. No 'ignition' light illuminated on tacho and fuel gauge dead. Also no tell-tale ticking from fuel pump.
Towed it home and tried a different tacho which is known to work. 'Ignition' light on tacho lit up, fuel gauge rose but no ticking from fuel pump. Thought i'd cracked it so checked connections on fuel pump; all sound and clean. Fuel pump only a couple of months old.Then went to turn ignition on again and this time the tacho light was off and no movement on fuel gauge.
I'm thinking ignition circuit, but where to start?
Car is a 1275, negative earth with electronic ignition from Simon BBC; always been reliable and fairly new.
Hel!!
aj robinson

All the bits that are giving trouble (ignition light, tacho, fuel pump and fuel gauge via voltage regulator) are powered directly off the ignition switch.I would first of all check with a multimeter that you have a sound and constant 12v supply from there. When things stop working, do the indicators work, and the brake lights? These are on the same circuit, but through a fuse.

If you don't have a multimeter, get one. They are dead cheap and so useful. Have a look in your local Maplins store.
Mike Howlett

Yep, Mike is spot on. I only have an early 1500 wiring diagram in front of me, but they should be similar. You should have:

1. +12v (brown) going to the ignition switch.
2. Two ignition on (white) wires coming from the switch that go to:
2a. The fuse box, to provide power to "green" circuits, wipers, indicators, heater motor, brake lights and the fuel gauge voltage regulator.
2b. A multi plug somewhere behind the dash which then feeds:
2b1. The coil, which then provides a signal to the tacho.
2b2. The ignition warning light.

As everything is dead (fuel gauge etc. point 2a), sounds like your ignition switch.

Hope this helps.
Malcolm
Malcolm Le Chevalier

Thanks guys, that was where I was going; ignition switch. I have a multimeter so will start from the ignition switch. Indicators NOT working. Should have said it is an IOW frogeye so has the frogeye style ignition switch with loads of connections!
aj robinson

How many keys are on your key ring....a weighty set of keys can kill a switch really fast
prop

Hadn't thought of that Prop, but Its only the one key on a small fob.
aj robinson

Prop,

Wasn't that a major headache for Chevy recently?
David Billington

This thread was discussed on 01/07/2016

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.