Electrics or Fuel?

[steve jukes]

I own a 1974 Stag, original engine and auto gear box. It is fitted with Lumenition electronic ignition and converted to run on un-leaded fuel.
After spending a small mortgage on the car during our first year of ownership it now runs well and feels safe and reliable, until recently.
It always starts very well and has a steady tick over but now occasionally at constant speed driving the engine will cut out completely, no revs, but then because it is still moving "bump start" itself back to life and carries on without a problem. This engine cut out lasts between 2 and 10 seconds, it has not yet stopped running completely and come to a stop.
Sometimes it happens only once on an hours run or three or four times or not at all!!! It is all very frustrating because the car runs fine apart from this and we have really enjoy using it but the reliability question has arisen again. I am not very technically minded, my interest is more in the bodywork and interior refurbishment, so I would value peoples opinion as to what this problem could be and how to solve it or to get it solved.

[V Mad]

It could be fuel or ignition but probably an intermittent open circuit somewhere. Clean the contacts on your inertia switch as this might be cutting off the fuel pump, or even the Lumenition if it is wired to that.

I, and others have had intermittent cutouts with the Lumenition system itself so that may be a cause.

You could rig up a small lamp to indicate loss of power to various suspect circuits.

[nib]

I would be inclined to clean the points in the fuel pump for a starters.
Mark

[tonyh]

If when it cuts out the rev counter drops immediately then it is something in the ignition circuit, if the rev counter does not drop then it's a fuel problem.

[steve jukes]

Thanks for the replies all food for thought. When the engine cuts out the rev counter does drop immediately so it seems likely to be the ignition circuit. I have fitted a new distributer cap and HT leads and cleaned. Could it be the coil or is it more likely to be on the LT side, leads or the Lumenition system?

[Guest]

I am no expert on Stags, but I'm learning! However, I find that in general, if the car stops immediately, it's ignition and if it splutters to a halt, it is fuel.

[V Mad]

have a look to see if your Lumenition is wired to the inertia switch.

[Jon Tilson]

Thanks for the replies all food for thought. When the engine cuts out the rev counter does drop immediately so it seems likely to be the ignition circuit. I have fitted a new distributer cap and HT leads and cleaned. Could it be the coil or is it more likely to be on the LT side, leads or the Lumenition system?

I would suggest its the supp;ly top the lumenition going intermittent. I had one on a dolomite and it was the connector to the distributor module that developed and intermittent contact. The twitching rev counter is the clue....intermittent low tension contact.

Jonners

[4x4]

I had an almost identical problem - but not as bad as yours.
Coming off the Lumenition is a 3 or 4 pin (can't remember which) electrical connector. I eventually found that if I touched one of the wires in particular, I could make the engine cut out. You have a male/female pin connection there, and the female side had spread a bit with age, giving an intermittent contact. All I had to do was jab something down inside the connector to close up the female side of the connector - problem solved.
If your's isn't something like this, I'd put money on a broken wire or bad connection somewhere around the coil LT side.

Good luck..............