EB engine stops on highway
In the past 3 weeks, a friends normally reliable standard EB Falcon GL (auto, 3.9l EFI (not MP), petrol, travelled 160k km) engine has stopped, without any signs of a problem, 3 times while travelling normally at highway speeds (80 to 110 km/hr), in the past 1500km. On two of these occasions I was present, so upon pulling over and immediately trying to restart the engine it turned over normally but refused to start and this repeated again after waiting for several minutes. However after 10 to 15 minutes, the car started normally and proceeded without problems. (on the other occasion the driver did not try to start the engine, except immediatley after stopping when it wouldnt start, so then waited until the service technician arrived about 1 hour later, when it also started normally)
Unfortunately the road service technician we called was not able to arrive in that critical 10-15 minute period, and seems unlikely ever to. His advice was that the fault was the "ECU chip", or a faulty fuel pump which (perhaps overheats and stops?).
The problem has so far only happened on hot (30 to 35C) days (air conditioner was not running as its comprresor is inefficient and needs replacing), on longer distance highway driving (not around suburbs), but this may be only because this has been most its environment since the problem first occurred. About one week before the problem first started, the car had a regular 10k km service and CD player installed by reputable mechanics. Petrol tank was between about 1/4 and 3/4 full for all 3 faults.
I am interested in:
1. what may be the cause of this problem;
2. what tests I can do, to identify or eliminate possible causes, either now or more particularly if it happens again (given a mechanic is not likely to be available in the 10-15 minute fault period). I have a digital multimeter and a few tools and can therefore check some electrical items.
thanking you in anticipation of assistance