If the HP pump could drag sufficient fuel to run the engine at all then the suction pump can't be that restricted. Normally a suction pipe is cut at an angle to prevent that sort of blockage. Reasonable point though. Is it possible to peer inside the tank or pull the dip pipe? Gently blowing on it should say if it's restricted... Does it have a filter on the end?
In order to check the flow it should be a simple matter to run a temporary pipe into a container and run the pump for say one minute, then measure the fuel?
My mind keeps coming back to this being a temperature related fault. The symptoms occur when the engine has been running for some time on a warm day and it has been gradually getting worse?
I think it's important to keep that at the top of the mental whiteboard.
This is the first concrete fault that has been discovered, until it's rectified no further solid conclusions can be drawn.
Having eliminated most if not all of the electronics, we seem to be left with the fuel system components and perhaps the fuel.
Given the pump seems to be US, why not slice it open and try to establish what has happened inside. That might be good info for us all, I think many of us rely on these Facet pumps, although I have fitted two, not trusting these new fangled things!!! The SU's were notoriously unreliable. That said, my understanding is that the Facet pumps work in exactly the same way just that they don't have the mechanical contacts. A plunger is pulled by magnetic pulse against a spring. The spring pressure presses on a diaphragm and pressurises the fuel through a one way output valve. So the pump shouldn't be overloaded by being unable to suck fuel, it should just lie idle, or pulse normally, as though trying to suck fuel, that shouldn't overload or over load the windings or circuit.
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