I am getting a continuous error code saying that my fuel pressure is too low and this is a faulty fuel pressure regulator . I thought the fuel pump just pressurized the fuel and that was it. I have searched the area of the fuel rail and I can't find anything. Is it in the fuel pump itself ? Why would it be sending a code that pressure is too low? The car drives well but has a history of occasionally dogging. The problem vanishes when the car is allowed to sit for a few minutes but this happens when the tank is low and I know I have far less gas than the gauge indicates. One other error code is present but I write that one off, troubled ambient temperature sensor. So where is this fuel pressure regulator?

Fuel pressure is controlled, at least to some extent, by the fuel pressure sensor (FPS) which is located in the end of the injector rail. But if your problem relates to tank level and the gauge is out whack, your problem may be in the tank?

Does your car not have this?

Yes I have looked at that thing and wondered if that was the issue. The check engine light is on and at rpm between 1k and 2k the needle gets unsteady and dogging begins. At first I thought it was contaminated gas ( I emptied some stored gas into the car at one point ) but the Auto Zone code reader comes up low pressure / fuel regulator issue consistently. That part is $207 at one popular internet parts site and $122 at another so I may gamble on it. I have a sending unit for the gas tank coming in the mail soon as well as I get the chugging of a car running out of gas at the 1/4 mark. This car is going through a serious death cycle as I have seen other Volvos do where I seem to replace something every two or three weeks and then the cycle ends for 40 or 50k.
Here's a link to the other part that might be the problem
http://www.fcpeuro.com/products/volvo-fuel-pressure-damper-genuine-volvo-9186278

Thanks for the photo. Those help a lot

If you're getting a genuine Bosch sensor for $122 that's a good price. Enquiring minds want to know your source. Make sure getting one for a turbo vs non turbo. They're different.

I got the part at www.fcpeuro.com formerly known as fcp groton. I usually shop www.ipdusa.com because I got three bad parts in a row from fcp years ago but now they have improved and turn out to be less than ipd in some items (they wanted $202 for this part ) . A quick check says that this part at " http://www.fcpeuro.com/products/volvo-fuel-pressure-sensor-map-sensor-0261230110" is for turbo models