I just installed a new sink sprayer(handle only, not hose). When it was tried out, it works, but It does not divert all the water from the tap and does not have as much pressure as it should coming out of the sprayer. I could be wrong, but isn't all except for maybe a dribble of water supposed to be diverted when using sprayer?

From what I have seen all it comes through the spayer

You have some crud in the diverter that's not letting the diverter to completely close. The diverter's located under the spout in the valve body. You must remove the spout to get at it. To tell you more I'll need the brand name of the faucet, the model if you have it and what type it is, one handle or two knobs. Regards, tom