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MG MGB Technical - Intermittent cutting out

My wifes GT has developed an intermittent dying of the engine, the car stops and then after a few seconds it can be started again, there doesnt seem to be any pattern to it at all. We've checked the ignition system and all seems well with nothing loose but the other day when this happened she said she heard a tapping noise behind her right hand side, fuel pump? Seems likely but has anyone else had something similar or how can we check?
Many thanks :-)
Colin

Check your fuel system starting with the fuel filter. Make sure the distributor wires (not the spark plugs leads) are not frayed or almost broken. Both of these were issues I had to sort out on a car out of storage.
Bill Haglan

Hi Colin

What year is the car ?.

Does the fuel pump go into a flurry of ticks before the engine restarts ?. Have you fitted a fuse in the fuel pump supply (recommended) in case there is a chafing wire near the pump.

If you have a gearknob mounted overdrive switch disconnect it at the bulkhead in case the wireing has chafed and is shorting the ignition switched supply.
Fit a fuse at this point if there isn't one already.

What does the tacho do when the engine cuts out, does it drop to zero immediately or slowly as the engine revs die ?. Does the tacho jump about in normal driving ?.

I would expect the engine to splutter a little before dying if fuel supply was the prob.

HTH.. Don
Don

What year? Always give this info as it can eliminate some possibilities.

Check the tach and ignition warning light before you knock it out of gear or switch off, i.e. when the momentum of the car is still spinning the engine. If the tach has dropped to zero it is an ignition LT problem. Could be the feed to the coil, coil itself or terminations, connection to the distributor, points, distributor ground wire, or possibly capacitor. Original coils up to some time in the 70s had the spades rivetted on and these work a bit loose and can give an intermittent connection, BT, DT. Later coils have the spades attached with nuts on threaded studs.

If the warning light comes on as well then you have lost the 12v feed to the ignition through the ignition switch i.e. from the brown onto the white. Check the multi-plug (if provided) by the steering column is pushed fully home and none of the pins have been partially pushed out of the back. Otherwise check connections on the switch, and the switch itself.

If the tach is still registering then ignition LT is OK, could be HT or fuel. I've had fuel pump failure where the engine suddenly cuts out, no spluttering. Likewise an intermittent connection before it goes open altogether can give spluttering.

If it looks electrical, and clears itself before you can track it down with a voltmeter, you can put the meter where you can see it in the cabin and connected to various points along the ignition LT circuit and track it down over time that way.
Paul Hunt 2

Colin - For a fuel delivery troubleshooting guide that may be of help to you, go to: http://www.custompistols.com/cars/dave/ddFuelDeliveryTroubleshooting.htm
Good luck - Dave
David DuBois

This thread was discussed on 23/10/2005

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