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MG MGB Technical - Headlights on - engine dies

On my way to the British car show Sunday, near here, I turned on my headlights, and a minute later, the engine seemed to stop producing any power.

As I turned off the freeway and slowed down to 50 MPH, or so, I turned the headlights off, the my 1977 MGB ran fine again.

Ignition light did not come on, nor did I see or hear anything else. Didn't even hit a bump in the road!

It reminded me of earlier this year, when my engine died - and as it turned, out, the rotor had gone bad - same sensation of no power in both of these cases.

Any ideas?

Thanks,
Greg

Greg Knodel

Check for a good ground where your tail lights and the fuel pump ground are common.
George B.

Greg, Autumn Classic?

Which B was yours?
Price

What's that little red light on the dashboard doing?.. i'm having a similar problem with my B and i've talked to a number of people about it and it seems to be popular belief that it's the alternator. When you start the car the red light comes on and then goes off when the car revs up, at least that's what's supposed to happen, but if it's coming on at higher revs then it means your alternator isn't charging... so check the fanbelt, and if it's tight, then go spend insane amounts of money to get your alternator rebuilt. Cheers,

- Dave
David Ryzuk

Greg - Monitor the voltage on the primary side of your coil (the terminal that goes to the ignition switch) and then turn on the headlights (this can even be done without the engine running). If the voltage drops to below 9 volts when you turn on the headlights, start ghecking for a ground on the headlight circuit or a bad connection between the battery and ground or the battery and the ignition switch. You can do this by walking the voltmeter back toward the positive side of the battery, checking each connection in turn untill you find where the voltage drop is happening. While you may have a bad alternator, the car should run fine on the battery even if the alternator is bad (I made it about 50 miles with the lights on and the generator on my MGB not putting anything out before the car quit), of course, this will not hold true if your battery is not holding a charge so that is something else to check. Put the voltmeter across the battery and turn on the lights without the engine running and check the voltage drop. If the voltage goes below 9 volts, then you have a bad battery. Good luck - Dave
David DuBois

This thread was discussed between 22/10/2001 and 25/10/2001

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