stevezab, are you on any meds? I know adex can affect my pump, I find the best way to gorge my muscles with blood is to lower weight a little bit and do a nice 3-5 second squeeze for barbell curls. If I want an awesome pump to where I can even bend my arm in, I will do 4 warm up sets of 25 lbs I hold my elbows tight against my side and curl the weight all the way out in front of my body all the way up, dont cheat! when those are done, do 4 sets of 50 lbs again, use flawless form, 3-5 second squeeze. I never just work my bis or tris, I always incorporate with chest or back. By the time im hitting curls, ive already done lat pulls, back pulls, rack pulls, and seated cable rows, so my bis are pretty warmed up by the time I hit curls, but I still like to get those light weight warm ups in using good form. That might help. Carbs are a plus, along with good hydration.