First let me introduce myself. My name is Ben, I am a automotive instructor at a technical college in Vermont. I teach primarily engine performance and electrical subject matter. I have a interesting problem that has me banging my head against the wall.

2006 XC70 2.5t

I do not have access to VIDA, i get all my information from Shopkey.

Engine codes for 2900 - Fuel pressure, faulty signal, 290D - Fuel pressure signal too low.

Engine runs but hesitates on throttle very badly.

I have measured actual pressure to be 20-25psi, relative pressure in the scan tool is typically a few psi higher and absolute pressure is typically 12 to 15psi higher. I've measure at the fuel rail and before the fuel filter and gotten the same numbers. The fuel pressure is higher initially on a cold start. its seems to me like once the engine goes to closed loop operation the pressure drops but i have not confirmed that yet. The pump is being regularly commanded to run at 85% duty cycle. i confirmed that number at the PEM with a DMM set for frequency.

The fuel pump has been replaced by another shop two times once with a aftermarket part and once with a OEM Volvo part. A different PEM has been installed with no change. I removed both tank covers and confirmed that the pump is installed correctly and that there is no kink in the tube from left to right side. I have checked all wiring going from the fuel pressure sensor to the ECU for resistance and shorts and that all checked out ok. 5v ref is consistent and signals when back probed with engine warm and idling are consistent with actual measured values.

I am beginning to lean towards replacing the pump as it seems to me that it does not seem capable of producing the necessary pressure. But i have seen some decent info on here and thought maybe i could garner some additional advice.

 

That's very low pressure, and duty cycle is way too high - there could be foreign material in the tank damaging the pumps or preventing proper operation.

 

In my 2004, there are a couple of Schrader Valves where you can measure pressure. One is at pump side of fuel filter and the other is at the end of the fuel rail.

 

Meant to add you should be getting 40+PSI for the turbo engine.