any one know why my vw t4 starts and ticks over but wont rev up?

i bought a doner van and changed the engine and box and loom from my 1.9td to a 2.4 5 cyl diesel, i drove the doner van 140 miles home so i know the engine is fine, i put it in my van and now im having trouble running it, ut starts but sounds like on 4 cylinders and it ticks over but when you rev it it takes ages to rev up and when it gets to around 3k it dies? i preasure washed the engine before i fitted it and think i might have got water in the fuel pump, anyone know how to drain a fuel pump? its a mechanical one