My 740 Wagon was running smooth untill it just quit on the open road. No restart. I had the wagon delivered by wrecker to my local mechanic and he promptly found a timing belt problem as the tension pully bearings were frozen and belt slipped. After replacing the belt and pully and reseting the time(hopefully), the engine will not start. The fuel pump runs, cylinders getting gas, coil sparks but weak ,and spark at plugs but seems weak. Could it still be a RPM sensor, with spark or maybe a power stage of which I have yet to find on either fender??Any other suggestions?

Yes it could be.
The power stage is mounted on a peice of aluminum on the inside of the left side fender.

Is there still a power stage module on a 740 with the rectangular coil?

I think so.You have the Regina Rex Ignition.

Is there any way someone,a previous owner , could have wired around or eliminated the power stage module? The wires from the positive side of batery have been tampered with as i can see the shielding has been cut open and maybe three wires replaced or added. The car ran fine for a year since I have owned it. The regina-rex systems coil is on the drivers side fender,with the coil wire going to the distributer, and two other connections going into the firewall. As stated before I am getting spark from the coil ,distributer and plugs. I will change out the crank sensor(RPM sensor) this evening. I know the power stage module would not be this difficult to miss on either side fender, as we have looked everywhere including removing airbox on drivers side and the battery on the passenger side.Surely it is not hidden anywhere else. This is what makes me think it is either built into the large coil housing on the regina-rex system, or has been removed. How can we research this futher and find out for sure,,HELP, and thanks.

I will do some checking and will let you know.
Also look on the passenger side and see if there is 2 black relays located on the coolant bottle.If there is try swapping the relays and see if it starts.If it does then you will need one of those relays.One is for the cooling fan and the other is for the fuel system.

Thanks, I tried swapping the relays to no avail. As near as I can tell the relay closest to the motor is the fuel relay or sometimes called radio suppression, Its job is twofold , first for fuel pump and second, i forgot, but seems like it also sends a signal to ECU. Is that correct? It could be doing its primary function and not the secondary, correct ?

It does send a signal to the ECM.
But if you swapped them and nothing then they are working properly.

Back to square one

Yes let me see what I can come up with.

Have you go the speed sensor in yet?

Speed sensor will arrive today from Atlanta around 3 PM. Will let you know the outcome of its installation. Thanks!

No problem.

Look what I came across,,,,,,,,


Note that the components for Regina differ from Bosch and you need to keep that in mind as you read FAQ notes. For example, the Rex system integrates the ignition power stage amplifier into the coil; Bosch has a separate unit.

I found out the regina rex coil has the power stage integrated within the unit. Still have not installed the speed sensor,will let you know results tomorrow I hope.

OK thanks for the Info.

The ole Volvo is now up and running , the sensor seemed to do the trick. I hope it will run another 214,000 miles . Actually I learn a lot each time something happens and I want to thank you for helping and for instilling that added confidence in myself. I will be in touch I am sure. Thanks again!

Congrats Im glad that fixed it.