What color paint would help sell my pump faster?

White with some double stripes. Worked for me twice. Neutral color. Also get a good broker.

Post a couple of pic's and lets see what we are working with.

why dont you paint it as the customer wants...

Whatever color hides the splatter. 

52putz, more splatter

go with the standard creme color. That is as neutral a color as you can get , if it is cleaned up and freshly painted the pump will sell itself. Plus if you go with a fancy paintjob the new prospective owner may not like your color choice .Just stick to the basics and make sure everything works when it is time to sell ..