2 replies to this topic

[Coupe177C]

im trying to make sure everything is wired up correctly on my mini engine which hasnt started in a while.

Im unable to test the HT leads with a spark plug at the moment due to fear or electricution lol so waiting for the old man to give me a hand with it.

So in the meantime i checked the other wiring involved.......

I started at the coil.

With ignition off im getting earth on the negative wires on coil and nothing on LT positive which seems normal, i then get power on LT positive with ignition on.

I tried testing at the 2 LT wires at the dizzy end and find that:

----- with the ignition off, i get nothing on + and earth on -
----- with the ignition on i get power on + and nothing on -

Is it normal to lose the earth from the dizzy once the ignition goes on? Im tempted to try starting it with the dizzy LT straight to earth but i dont want to break anything if its doing what its supposed to do.

I havent checked if i lose earth at the coil end when i put the ignition on but will update on that later

The haynes says to check resistance between LT+ and HT on coil and HT to body of coil to test if its faulty. Am i right to assume that this should be done with the ignition off? I dont know much about HT coils but i get the impression that i should be staying as far away as possible from an exposed HT terminal when the ignition is on, or am i being over-sensitive

[Ethel]

You're probably being a little over cautious, which doesn't hurt.

You don't say what ignition system it is, I'm guessing electronic if you have 2 wires at the dizzy. It also explains why turning the ignition makes a difference to the -ve side: energising the module will allow it to operate and close the earth.

Resistance should be measured with all power turned off, you can't measure resistance directly so your meter measures the voltage drop from a voltage it supplies to work it out.

[Coupe177C]

Thanks Ethel.

I hadnt considered if it was electronic or not as at the moment im just looking at everything and pooing myself

However, i think youre right. Looking in my trusty Haynes manual Page 318 its got an exploded view of what looks like mine with 2 wires going into the amplifier module. It does say its fitted to later 1275 models but i thought mine was 1l. I guess thats another thing i could do with finding out. I came to the conclusion that it was 1l after looking at pics of the engines and thinking that 1l had the oil filler over to one side of the rocker cover but the 1275 had it in the middle. I would love it to be 1275 though!

On the plus side though, from what you say, its right to be cutting the -ive so i'll have a crack at testing with a spark plug tomorrow and see how that goes.

Its a nightmare working with dizzy in the GTM, not sure if mines mounted too far forward but it so close to the bulkhead (mid engined) that I dont think i could get all the leads off the dizzy if i tried!

I'm definately getting fuel up there now without the filter in place so thats a plus. Once i can get it running reliably i will put the filter back in-line and see how it goes.