If the fuel pump on your 1600 Nomad fails and you don't have warranty coverage, a new pump runs $400-$500 from a dealer. They are sealed units and have no serviceable components.
However, there is an alternative. The fuel pump used in the 1600 Nomad is made by Mitsubishi, and it is the same pump used in the 1989 Mitsubishi Galant. I just checked Autozone, and the pump runs less than $135. You can also purchase the pickup screen and filter to go with it.
Autozone PN # E8023
http://www.autozone.com/autozone/par.../N-ihhkaZ8vcz2
Warning: As of now, this is all hypothetical information. I have not personally validated this information because I have not replaced my fuel pump. If someone attempts this replacement, please post your results, positive or negative.
NOTE; Another fuel pump to try is PN # E8455 which better matches the Vulcan part. Perhaps Kawasaki used more than one pump on the bikes, in different model years. Make sure you take your old pump with you when your comparing, so you get the correct pump.