voltagedrop while cranking

[Sjorz]

Can someone tell me, what the minimum voltage is on the + site of the ignition coil? The engine will only start running when I release the ignition switch from cranking.
Cranking power is still sufficient in mine opinion.
I measure 9,5 volt while cranking, and with the engine running almost 13,5 volt.
When i put a other power source on the + site of the coil the engine start immediately.
It's a rover v8 3,5, with the ignition module at the back of the coil.
In participation thanks.

[Paul B]

Can someone tell me, what the minimum voltage is on the + site of the ignition coil? The engine will only start running when I release the ignition switch from cranking.
Cranking power is still sufficient in mine opinion.
I measure 9,5 volt while cranking, and with the engine running almost 13,5 volt.
When i put a other power source on the + site of the coil the engine start immediately.
It's a rover v8 3,5, with the ignition module at the back of the coil.
In participation thanks.

You may have the coil connected to the wrong place, so it is disconnected when you're cranking, then connects to power the second you release the ignition. There is some sort of device inside the starter that does this to do with a ballast resistor, not sure of the exact details.

Measure supply to the coil when you're cranking see if you actually have any power going there.

Or was that 9.5 actually measured at the coil when cranking??

[Sjorz]

Yes Paul,
It was measured on the coil while cranking. I will measure tomorrow what the voltage over the battery is while cranking. Perhaps is the cranking power of the battery the culprit.
When i put a extra power source (battery charger) on the coil, it will run immediately.
Regards,
Rob

[ChrisJC]

I think you must have a wiring fault. 9.5volts on coil +ve is sufficient.

Chris.

[Sjorz]

Chris,
But when I put a extra power source on the +ve of the coil the engine runs immediately.
Can it be the ignition module?
I have emptied the aluminium box and only connected the ignition module. Last spring I have had the same problems. The engine refuses to start then completely.
And after the splendid advise over here, a have removed al the junk out the ignition box and after a good charge of the battery the engine started (until now) always direct.
Regards

[Ian Anderson]

Once it is running what voltage do you have at the coil?

You may have a 12v coil on a system designed with a resistor to drop coil volts to 9.

Ian

[Sjorz]

Ian,
As I mentioned earlier, 13,5 volt while running.
Regards

[ChrisJC]

Have you got some pics of the coil, amplifier & distributor. I wonder if there's a mismatch somewhere....

Chris.

[Paul B]

Yes Paul,
It was measured on the coil while cranking. I will measure tomorrow what the voltage over the battery is while cranking. Perhaps is the cranking power of the battery the culprit.
When i put a extra power source (battery charger) on the coil, it will run immediately.
Regards,
Rob

Hmmm, you do have the amplifier well grounded don't you?

It this the ignition system that came with the motor originally?

You don't have a ballast resistor tied into the system at all do you?

Usually the starter would switch the ballast resistor in and out of the system automatically.

On my Morris hot rod I had a 12 volt supply running direct from the ignition switch to the coil, as the coil is 12 volt on that type of ignition.

[Sjorz]

Hi Paul,
It's indeed a 12 volt system without a ballast resistor.
This winter a have bought a new distributor with a ignition module on the outside. This one is removed and I use the original amplifier behind the coil.
Yesterday I have tested the battery by a expert and was ok only discharged.
This night a have give it a long charge an this morning the car started immediately.
Tomorrow I will test the alternator under full load (lights, electric fan etc)
Thanks you all for the quick and helpful advise.
Regards,
Rob