Ford Repair: 1989 4.0L ford falcon, ford falcon ea, voltage input

Question
Hi,
I have a ford falcon EA 4.0L 1989.A few days ago it started having a problem after running for any time between 30 minutes to an hour.It fires up the first time and runs beautifully and then after time it cuts off.It will crank over but will not start.When this happens i have checked for spark at no 1 cyl,there is no spark.If i leave it for 1.5 to 2 hours it will start and run perfect again for a while and then cut off.I have replaced ignition relays etc but the problem is still there i cannot use the vehicle as it will leave me on the road.Do you think the coil may be faulty ? Please help.
Thank you

Answer
Well, it could be a bad coil, but I wouldn't replace any parts without further testing.  Electrical parts are usually not returnable, and it could cost more replacing parts that aren't defective than having the problem properly diagnosed by the dealer.  You could test the primary voltage at the coil; if there is no secondary output while you have primary voltage input, the coil is most likely bad.

I hope this helps,
Dave