Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Morgan 4/4 1600 1972 - electrical issue

Driving down the M27 the other day the engine suddenly cut out and the tachometer dropped immediately to zero. I coasted to a halt, waited a couple of minutes, restarted the engine and off I went. This was repeated five times on and off the motorway before it finally wouldn’t start at all and the car was recovered to home.

I’ve discovered a dodgy connector joining a single wire from the ignition switch to two other wires (a Lucas WT74 double bullet connector) which I’ve replaced and I’ve by-passed the isolator switch in the passenger footwell and now the engine starts.

My concern is that I’ve addressed a couple of possible causes but wonder whether there are others I should look at before going too far. The next big trip is to France and I’d really rather not have a known problem recur then.

Grateful for any ideas.

Mark

Mark

It is a long time since I worked on a Kent engine , but I seem to remember that the ballast resistor in the ignition circuit was more often than not a culprit when it came to intermitent electrical faults.
I must admit that I can no longer remember the best fix , but Google it and see what comes up.

The ballast resistor comes up on here regularly. I am sure others will get back to you

As John says this has come up as an old favourite on here.

I've known ignition coils to break down in the heat too.

There is a school of thought that the best thing to do with the ballast resistor is to do away with it but having said I've never had a problem with the one fitted to my 1972 4/4.

I think you've probably identified the root cause of the breakdown being a loose connection. I've never been a fan of bullet connectors but what can you do other than to carefully check each connection and clean if necessary. I do this as part of my pre MoT spanner check. I use a small glass fibre pencil There was also spate of badly fitting female bullet connectors on the market a few years back which wouldn't grip the bullet and required a pinch with a pair of long nose pliers!

Is the isolator switch in the footwell a later addition? Presumably its cut into the low tension circuit?

Might be worth taking a spare coil, ballast resister and condenser with you though as they take up minimal space!

Arwyn

Previous posts will indicate that I had a similar problem on a '71 4/4 fitted with Lumenition electronic ignition. I bought and fitted a new coil and ballast resistor but after installation I found that the car wouldn't start at all. I then found that the "king" lead (coil to distributor) had a possible break in the carbon core. I fitted an old lead I had kicking around and the car started instantly and has run without interruption so far.

Thanks all.

Looks like I should replace ballast resistor, coil and king lead, just in case.

I suspect the isolator switch in the footwell is a later edition. It is the first point on the positive side from the battery.

Mark

Try checking the voltage on the positive side of the coil, the ballast resistor should knock it down to 9 volts. Have you thought of changing to electronic ignition? I've had an Aldon Ignitor on mine for nearly 20 years which hasn't missed a beat.

I agree with Arwyn about the spares and a copy of the wiring diagram would also be a good idea.

One further question - any idea where the ballast resistor is located, please?

I haven't ever owned a car of your period but you are looking to trace the White/Yellow lead from the SW connection of the coil and you should find it according to the diagram below.

http://www.gomog.com/allmorgan/wiringdiagram1969to1973.jpg