Hi,
I have a 1991 740 GL, B230F, LH2.4 (350.000 km) that has been running without any problem the last years. Sometimes during the last weeks it has been a little bit difficult to cold start (it has taken maybe 3 seconds instead of the usual 0.5 seconds before it starts). Then all of a sudden it didn't start at all (warm) and since that it has never started, niether cold nor warm.

I do not have the equipment to get error codes from the control unit but i have found out that:

1. The engine turns as usual.

2. If i disconnect a plug i see a spark at regular intervals (as usual).

3. There is no fuel at all coming out through the fuel injectors (no wonder it doesn't start).

3. There is fuel coming to the injectors through the hose from the fuel pump (as usual).

4. The fuel pressure regulator seems OK (no smell of fuel at the vacuum side, no fuel dripping at the vacuum side when disconnected, strong smooth flow of fuel through the return hose.

5. The radio suppression relay is OK (12V at injector termninal connected to the RSR) when ignition is on.

6. The connection between the control unit and the injectors is unharmed.

7. There is no (or very weak) signal from the control unit to the injectors. The voltage between the injector terminals when trying to start the car is never above 0.5 V).

8. The voltage at pin 1 of the control unit drops when i try to start. If i've understood my manual that means that the control unit gets information from the ignition control unit about the RPM.

9. The engine coolant temperature sensor is OK, again if i've understood the manual. (a bit more than 2 kOhms between pin 13 of the control unit and ground at 20C/70F).

10. The throttle position switch seems OK. I hear a click when it opens. I've also measured 0 Ohms between pin 2 of the control unit and ground when accelerator is not pressed and 5 kOhms when it is pressed.

11. I've tried to disconnect the air mass meter but that doesn't change anything.

12. The exhaust pipe does not seem blocked. I can feel puffs coming out through it when trying to start the car.

That is as far as i get. Can anyone help me to find out why there is no signal to the inectors?

best regards,
Leif