my 1986 xjs v12 jag was running mint yesterday until it just quit, started it up again started chugging and had no power, no she wont turn over, took it to the shop for a tune up earlier in the week fuel pump is working and there is gas in the tank i have spark at the coil but no spark at the plug. any ideas on how to fix?

 

I would check the rotor in the distributor. Or the cap itself for burn traces inside or wear

 

How do you mean She won't turn over?

 

Agreed with OB.

Terminology gets screwed up a tad sometimes.

Turning over, means it rotates but does not start.

Not turning over means exactly that, the engine will NOT rotate at all.

If you got spark OUT of the coil, and ZIP at the plugs, the carbon contact brush inside the centre post of the cap, and makes contact WITH the rotor, does burn away, and that is becoming very common.

The symptoms you mention are exactly the symptons I have experienced a few times, and that spring loaded carbon brush was the culprit.

Not sure where you abode, but down here that carbon brush and spring is a GM part and readily available as a spare part.

 

the motor turns over but it will not start and run

 

OK,

Remove the distributor cap, CAREFULLY note the spark plug lead orientation BEFORE ripping into it.

Turn the cap over, and look at the small carbon brush in the centre. If its gone, there is your issue, If its still intact AND in good condition, we will move on to the next likely culprit.

Look at the brass strip of the rotor, and ensure it is NOT cracked. This is very rare, but I have had one with that issue.

We will eventually need to know what market car this is, so please insert your place in the world in your CP area, so guess work can cease.