11 replies to this topic

[Bonniedog]

Hi,
I’m stuck with a problem with my mini and am hoping someone can point me in the right direction please.
I have a 1991 1275 spi, I’ve used it in the Mighty Mini race series a few years ago and am hoping to get back out in it next year at some point.
The problem started following a recent engine rebuild. On putting everything back together the engine suddenly refused to rev past 3,500 rpm. I changed numerous things and the only thing that made any difference was replacing the relay module (part number YWB10022). The engine seemed to go back to normal, was running well and revved away quite happily but then refused to switch off! Switching the ignition off made no difference neither did the battery cut off switch!
Got a smell of warm plastic and a little bit of smoke coming from the box with the cut off switch in it. Ended up disconnecting the fuel pump to stop the car.
I have very limited knowledge/experience with car electrics. Never had this problem before, the kill switch and ignition switch have both worked perfectly in the past. As far as I can see everything is connected as it should be, all fuses etc look ok. For the sake of a couple of quid I replaced the resistor, just on the off chance, but it made no difference at all, there was no smoke the second time around but the resistor felt very hot by the time I’d got the fuel pump unplugged and stopped the engine.
Any help/pointers would be gratefully received.
Really hoping for a relatively easy fix/list of things to check before I have to remortgage the house and call an auto electrician!

[Sussex_pete]

Immediate thought is that you have got an alternator supply to the wrong side of the cut-off switch. Thinking of the wire that normally runs from the alternator to the solenoid. I maybe wide of the mark, but seen it before like this on other cars

[Bonniedog]

But the switch worked perfectly before the relay module started playing up. I’ve not touched the wiring for it other than replacing the resistor

[kit352]

Sounds like the relay fused and didnt switch. Too much power maybe? Can you check the relay with a meter to see if its switching and how much voltage its getting? Do you have the relay hooked up properly- low voltage on the relay side and high voltage on the switched side? Its really easy to mess them up.

[mikal]

Stop the engine by stalling it..

[Bonniedog]

Stop the engine by stalling it..

Not sure the scrutineers will be happy with that as a plan!!

[Bonniedog]

Sounds like the relay fused and didnt switch. Too much power maybe? Can you check the relay with a meter to see if its switching and how much voltage its getting? Do you have the relay hooked up properly- low voltage on the relay side and high voltage on the switched side? Its really easy to mess them up.

The old relay pack is knackered and has been replaced. Having looked inside it the fuel pump relay is black and looks to have cooked itself. The new relay pack works fine in terms of the engine revving as it should but with the new relay pack fitted the engine won’t shut off either with the original ignition switch or the cut off switch.

[dotmatrix]

are you sure your kill switch is wired up correctly? my switch disconnects the battery and disconnects the power to the ignition coil.

[Bonniedog]

Yes, as above everything worked perfectly for two years before the relay pack died. Ever since I replaced that this new problem has started

[nicklouse]

i would be checking the wiring again. or getting another set of eyes on it.

[cal844]

i would be checking the wiring again. or getting another set of eyes on it.

I'd second this, it's so easy to wire replacement parts wrong, been there, done that... Thankfully I'd noticed the mistake in time, so no damage caused.

[GraemeC]

I’d test out the isolator switch with a meter - whatever fried the relay could easily have welded some contacts together in the switch.
Unfortunately some of those kill switches aren’t as reliable as you’d expect for a safety item, although they usually go weak and fail open.

Edited by GraemeC, 27 February 2019 - 10:37 PM.