Where is the fuel pressure regulator on my C70 convertible?
 

I am going demented trying to find the fuel pressure regulator on my 2005 C70 convertible. It is not under the fuel rail; it is not at the end of the fuel rail (although the local Volvo thinks it is and I sent them photos to show it isn't); it isn't alongside the fuel filter and I can't see anything like it near the steering rack. I think it's the cause of the car not starting in warm/hot weather as we have checked everything else. What I have found on the car shown in the attached photo has been described in info I found on the net (an info sheet of the control system fuel supply on an 2005 XC90) as control system, fuel supply -its the circular item which is connected to the manifold and then has a thin pipe which disappears. Does anyone know what it is? My car seems to be a rogue version as it nearly always needs the parts listed for another model. Help please.

I'm afraid I can't help you, and I'm not sure what that piccy indicates, but mine a 1999 model I suspect operates the same way. There's no regulator in the fuel rail, despite claims that it's there. I believe some do have it there?
Mine: A single pipe goes to the rail such that excess pressure could not vent anyway.

I've looked in the past and never understood its operation. All i can say is, by the sounds of this... yours is like mine.

I'm pretty sure that the fuel is regulated in the tank I vaguely remember see a reg on the sender unit on a C70

That'd make more sense, there's only one line going into the filter (sited near back axle on my V70). Over-pressure must vent before then. My guess is the blow-off is done at the pump.

What I don't understand is how, as the OP's issue... how is excess pressure vented on a hot day? We've all seen a plastic petrol-can expand in August, how this system deals with that - or in the OP's case doesn't - I don't understand.

Because it's a factory Bifuel thus I've looked into mine to try to stop the small amount of liquid use when running gas. I tried to vent liquid, and epected to vent pressure back to the tank. There's no return rail from the engine-bay, thus I got 'frit'. Clueless messing with August over-pressure sees me heading into Darwin Award territory, I stopped.

Thank you for your responses. My C70 definitely has two fuel pipes running to and from the tank. Alongside the fuel filter it has something called a rollover valve which I assume is some sort of tank venting system. See photo.

I am intrigued by the circular part behind the engine and better photos are attached. It is connected to the manifold so obviously works with a vacuum and a metal pipe, like a fuel pipe, comes out the back and then under a heat shield so I can't see what it is connected to (even form underneath the car) but it is in the direction of the fuel line. What is it?

The item in the first picture is the FPR....

Really? The local Volvo dealer didn't seem to know and described it as the 'roll over valve' part number 1255422, now no longer produced by Volvo only available from the aftermarket. So the roll over valve is actually the fuel pressure regulator?

The roll over valve should be at the back of the car.....

I may be struggling with your images, the first picture actually looks like it may be at the rear as I can see the fuel filter?

pictures 2-3 are the waste gate actuator