1990 760 GLE B280f motor. For the past year I have had a problem with the engine cutting out on several occasions when I stop at an intersection. The car
will not restart for some time 1/2 to 1hour.There is a spark at plugs and fuel rail is presurized OK.Had car taken to workshop when problem first ocurred,they could not find fault as car started and run perfectly by the time they got round to try o find the trouble.They suggested that the power amplifier was probably the culprit so I replaced that,but that has not fixed the fault.The car starts and runs perfectly other than for this unpredictable cutting out.
Thanks for any help with this problem
Bill M NZ

P.S. See also in FAQ engeen electrical

I Suppose your car has a radio suppression relay (RRR). If yes, first check it.
RRR gives power to injectors, if it is defective (small crackes in the relay) then your described effects can happen.
Whe your car does not restart, remove the radio suppresion relay and put a jumper between Gr-R and R wires or put an used good RRR (If any).

If car starts normaly then your radio suppression relay is defective.
Please check for wire colors in a manuel or in the net.

I hope this will be your solution.
Gen

Thanks for your reply Gen. I will check the radio suppression relay. I have also been told that the fuel pump relay can be a problem as it provides power to the injectors. Will now go on a relay hunt. Thanks. Bill M NZ

You might also check your RPM sensor and Ignition module, i experienced similar problems as yours with my '91 740 and thought at first that my fuel pump relay is the culprit, changed the FPR but problem still exist...took the car to a volvo mechanic and diagnosis came out that my rpm sensor and ignition module were faulty. Hope this helps.