XUD9 Ran Out of Fuel - now no power!

[FLOlive]

This is my first post and I'm hoping for some help from across the pond since there is not a lot of expertise on these here in the states. So I have the XUD9AI in a lawn mower (toro 455-D groundsmaster) and the fuel gauge doesn't work very well. I ran out of fuel the other day. I changed the fuel filter and primed the system and got it running. But now it will not rev up much above idle and has limited power. It runs smoothly (almost too much so) until it is under load and then it starts to choke down and struggle as if it is starving for fuel. It has a Lucas pump.

I've checked for air leaks. The fuel filter was very dirty when I changed it. Anyone ideas on where to start... pump, injectors? It was running fine before so I'm thinking it should be something simple.

Thanks.

JC