Bad earth or coil?

[Sprinter]

On a ride my NC30 lost alot of power, it's only firing on the rear two. When testing for the lack of firing I put a scewdriver in the ht leads of the front cylinders and it didn't shock me . Where are the key earth points? I cleaned the coil earth and mount but still no luck. Any tests for a duff coil?

[arsey30]

Swap the coils over to be sure.
Primary resistance 2.5 to 3.5 ohms [across the low tension spades]
sec res 14-24k ohms between ht leads. [leads connected]
11-14k ohms across the coil ht pins. [leads removed]

Dave.

[Sprinter]

Cool, I'll give that a go.

[Sprinter]

I've fitted a new coil it still doesn't work, cleaned up the contacts on the coil mount and the engine mount and fitted one of ricks earth upgrade kits (bar the last thick black cable). The tacho has also stopped working, all the fuses are ok.

Any ideas?

[Neosophist]

I've fitted a new coil it still doesn't work, cleaned up the contacts on the coil mount and the engine mount and fitted one of ricks earth upgrade kits (bar the last thick black cable). The tacho has also stopped working, all the fuses are ok.

Any ideas?

You have a bad earth or bad CDI.

Do you have voltage to the coils?

Check the earths.. there isn't many.

[Sprinter]

To check the voltage just connect the multimeter the the spade connectors and switch the ignition on. Is that correct? The earths I know of is the one the battery goes to and the engine mount by the front coil, any others?

[Neosophist]

Yeah.. you should get 12volts.

I'm not sure on the NC30.. is there a speciifc earth for the CDI? Somebody will have a wiring diagram to hand no doubt!

[Old Painless]

I think there is a CDI specific ground wire.

[Sprinter]

Discovered the issue, the top connector to the cdi was slightly undone.