1991 turbo 940 no start

[robert santi]

i have a 1991 940 turbo that just went dead in the driveway. i have tried to crank it but it seem to me that i'am not getting any spark down to the plugs or out of the coil. i have called myself checking everything in the system but still can't get it to fire. the two wires to the coils pos and neg sides should there be voltage there when the key is turned on? need help in t/s this problem on where to look and if i overlooked something..thanks

[billofdurham]

The low tension positive should show a reading when the engine is being cranked, but it is an intermittent reading. As the engine turns LT pulses are generated and are then amplified by a control unit to the level necessary to drive the ignition coil. The coil converts the LT pulse to High Tension pulses which pass through the distributor cap and thence to the plugs.

Try connecting a test light to the positive and to earth (ground). If there is LT current the light will flash as the engine cranks.

If there is LT current remove the HT lead from the centre of the distributor cap and, using insulated grips hold the end about .25 of an inch away from the engine block. Have someone crank the engine and see if there is a spark there. If not suspect either a dead coil or, cheaper, a bad lead from the coil.

Further checks can be made by reconnecting the centre lead, if a spark was seen, and removing a plug lead and trying the same test as above.

Bill.