I just got a call from the shop where I took my car to, (to fix the vacuum leak that I couldnt find) and the guy says I have no trailing spark.

I've noticed this before, because when I first put the engine in, depending on how you adjusted the timing the trailing spark would work, or it wouldnt. The guy says it might be a grounding problem, but I have all three points on the efi harness grounded. (stripped down drivers side harness)

Do any of you know what could cause the trailing spark to go out?

 

If the tach works, you have trailing spark.

 

Did he pull a trailing plug wire and ground to determine if trailing not firing? If he didn't have him try that to be sure trailing not firing. Could be spark, but plugs not firing, which would not give a signal on certain types of timing lights.