1995 Vauxhall Tigra hard to start when engine warm

hope someone could shed some light on this my tigra runs fine but for example if i stop at the shop after driving and engine warm and try to start it about a miniute after it does'nt want to start if i pump the acelerator eventuly it goes quite a bit of black smoke out of the exhaust but then fines fine if it's left for 10mins or so it starts fine...