The V8 Owners Forum -

Hello. I've just fitted a 3.9 v8 injection engine into my landrover. Think i've wired it in alright but not 100% sure. When ignition is on i've got power both sides of the coil? Don't think it should be like that. Anyway i've got no spark. Can any body help?

Thanks, Martin

currymonster wrote:Hello. I've just fitted a 3.9 v8 injection engine into my landrover. Think i've wired it in alright but not 100% sure. When ignition is on i've got power both sides of the coil? Don't think it should be like that. Anyway i've got no spark. Can any body help?

Thanks, Martin

I might be wrong but I think that if you put a volt meter from each side of the coil to the chassis it will read 12 volts. Power is fed to one side of the coil but the other side will "float" up to 12V. The ignitor box fires a large negative spike at one side of the coil when it wants to fire the plug. This spike creates a large voltage potential across the primary side of the coil which then induces the HT volts.

Points work the coil in the opposite way, there will be 12 volts across the coil terminals as long as the points are closed. When the points open the voltage across the coil collapses and this induces the HT voltage.

Regards,

Pete

MY coil died today. Try attaching a car battery charger either side of the coil with the ignition off (note correct + / - orientation or you could damage other parts of the vehicle electric system). When you do this your fuel pump may come on, but don't worry.
Wearing some rubber gloves (don't say I didn't warn you!) pull the kinglead from the dizzy and hold it about 5mm from any earthed point on the vehicle.
If you get a big spark arcing across then it's alright and your problem lies elsewhere.
If there's no spark, then your coil as shagged. Good news is they're only £12 new, or free if your mate recently converted to diesel like mine did (yes I know he's a mug but there's no telling him )

try lifting the rotor arm up from its fitted position about 3mm and try again, have also checked to see if the carbon in the centre of the cap is is touching the top of the rotor arm