So I finally decided to pull the pump and find out why it's leaking diesel down the back. Most likely the cold start seal, so everyone tells me.
Buy a seal kit, replace the cold start seal, and notice after a few minutes before install that there's diesel weeping out of the seam between the pump and the head, but only on the engine side.
Drat. As much as I feel I could pull the pump and replace the seal (it can't be worse than working on the helicopter turbine fuel governers I used to do), I think this is a job better left for Giles.
Anyone else have a different opinion? Is this a do-it yourselfer type of thing?