2005 v70r NA stalled and won't retart, fuel pump?

[DGM]

My understanding of the fuel system for a V70R 2005 is that the CEM provides "power" to the PEM (4/83). See the diagram I posted earlier. Battery voltage is applied by the blue (BL) wire to the pin 2 of the PEM. Ground is applied on pin 3 permanently by the black wire (SB). When the CEM send battery voltage to the PEM on pin 2 the PEM is ready to command the pump. The trigger is coming on the yellow wire (Y) from the ECM on pin 1 of the PEM. The signal is PWM (pulse width modulation). In short the longer the duration of the pulse the faster the pump will run. Pin 4 & 5 of the PEM run the pump. Under normal condition if the pump runs faster, the pressure rises at the fuel rail. This is detected by the fuel pressure sensor at the end of the rail. The sensor translates the pressure in a varying voltage (0.5 to 5 volts) to inform the ECM. Based on the pressure the ECM will call for more or less fuel by increasing or decreasing the duration of the PWM signal (yellow wire). This is a close loop system and it is self adjusting. Any component of the system can cause it to malfunction.

Personally if I would have this problem I would disconnect the PEM and at the connector verify ground continuity on pin 3. Then battery voltage on Pin 2 with ignition on. Then run the pump with external power and verify for fuel pressure at the rail with a mechanical gauge. Check for a bad fuel Pressure sensor (FPS). Normally it is giving a code though (P0089). The fuel gauge is it giving a good indication? Fuel in the tank? It may look silly but you know this can happen.

Hope this help,

Regards,

[view836]

DGM, thanks that's very specific and very, very helpful. So role of CEM is ruled out of the Blue wire is successfully supplying battery voltage and the Black wire has a good connection to Ground, and I guess if the voltage differential between the two does not sag when the current/fuel demand increases (a bad connection with high resistance might not be able to flow the necessary current). The crucial signal comes from the Yellow wire from the ECM (i.e. the call for fuel) which would mean potentially it could be the an issue with any of the sensors that contribute to the calculation of the fuel call by the ECM?

[DGM]

"So role of CEM is ruled out of the Blue wire is successfully supplying battery voltage and the Black wire has a good connection to Ground, and I guess if the voltage differential between the two does not sag when the current/fuel demand increases (a bad connection with high resistance might not be able to flow the necessary current)."

Volvo introduces in 2005 a new CEM with relays built in the unit. We can't swap the fuel pump relay to test the connection as before. Reading the voltage is one thing and the ability of the circuit to provide current is another as you mentioned. A bad CEM power feed can't be ruled out.

"The crucial signal comes from the Yellow wire from the ECM (i.e. the call for fuel) which would mean potentially it could be the an issue with any of the sensors that contribute to the calculation of the fuel call by the ECM?"

Yes assuming the PEM is well powered and in good order. Also connections to the pump must be checked.

[view836]

Well, what was being said to me by the advisors didn't exactly jibe with what is written on the dealer repair invoice, but according to the invoice the residual issue after the pump, filter, and PEM replacement was a bad fuel pressure sensor that provided a positive pressure reading even when pressure was zero. I am flying back to the USA tomorrow to pick up the car and drive it back, wish me luck!