Odd starting ritual: Balance resistor ?

Doug

Doug

Member
Hi all

Do Commers have a balance / ballast resistor ?

Here's why I'm asking..
Our van is having trouble starting (again). We now have a nice shiny new Weber carb, and once started he goes with no trouble, so I don't think this is fuel related.

However when starting, it seems that there's no spark (or a weak one) while the engine is turning on the starter motor, but when you switch off the motor back to just ignition, he tries to fire.

When he's warm, it's quite marked: spin on starter motor .. wheee.. stop the starter, he fires and starts right away.

As I say, once running he's fine.

I guess he's behaving as though the ballast resistor circuit is shot, but I thought commers didn't have one? Just a straight 12v coil ? I think he's quite original on the whole so I'd be surprised if someone has added one.

In case it's relevant, the starter has just one huge cable going to it.
cheers in advance
 
I think it could be either, Harvey is straight 12v but Bonnie is ballast- she is a '69 so a couple of years older. It should say on the coil but if the resistor has failed the engine would start but only run while the starter is engaged. It would immediately die once the starter switch was returned to the normal run position. The Ballast Resistor could be removed from the circuit and the engine would operate properly except the coil would run hotter and fail early so best to replace it with a normal 12v one.
Try running a separate wire from a live connection straight to the + on the coil, this will prove if the supply is at fault.
 
Aha, Roland is a '74 PB so perhaps they started putting ballast resistors in by then. The coil was replaced so I'm not sure what it is (no writing on side).

I'll just have to trace the wires I guess. I'll try the live -> +ve coil trick. It worked for me in the past on another car.

thanks yet again, Panky
 
Hmmm, must be because Bonnie is fitted with an old Lucas electronic ignition.
 
Confirmed: 12v at Coil +ve, ign on but starter not switched on.

(ie Martin';s right, as if there was any doubt)

Turns out the new coil had failed and was giving a very weak spark. New 12v coil has fixed it.

What would cause the coil to fail ? The garage guy said it was a 12v one and wants it back so he can complain to his supplier.
Me: I'm a bit nervous about it happening again, so I'm searching out a spare. Just noticed Martin does them, so will order.

Would the heat in the engine bay have killed it ? any other known causes ?

D
 
A lot of modern coils are pretty crap, Lucas are no longer real Lucas and are made in the far east - and yes heat and vibration will kill them even quicker, try mounting it on the inner wing. Next time you're at an auto jumble see if you can pick up a couple of old coils, they will probably last longer, or get one from the Distributor Doctor - he has a good reputation for ignition stuff.
 
Aha, yes I thought of mounting it in the space under the driver's bum (on the passenger side, the air filter is in the same spot). Is that where you mean ?

It'll be out of the way then, too.

I have several spare 6v coils from various old car purchases. If I put a ballast resistor circuit in, presumably I can use those ? Or would I need a different condenser etc ?
 
Yep under yer bum.
Six volt is no good I'm afraid they will burn out very quickly, ballast systems run on 9v with a 12v starting circuit - at least that's what it is on a Mini.
 
Oh, maybe they're 9v then. All the writings rubbed off most of them, but they're from triumphs generally, 2500 and stag.

I can check the coil wire voltage on my triumph 2500s to be sure :)

thanks for the info
 
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