I'm taking coumadin, (warfarin) I just had a total left hip replaced I was wondering if I smoked some weed will it affect my blood or healing wound?

Yes. Yes, smoking anything can cause arterial vasoconstiction which will decrease blood flow to wounds and thus decrease oxygen delivery to tissue. It can and will effect wound healing.
Most likely. Smoking marijuana after having surgery is generally a bad idea. Even if you weren't on coumadin (warfarin). Smoking (cigarettes or marijuana) will inhibit your natural healing abilities. Healing takes longer and there is more chance of complications. Adding Coumadin (warfarin) to the mix only makes it potentially worse. Just avoid the marijuana all together to be on the safe side. You can't be wrong that way:-).