Those members' committee assignments could be on the line, according to a spokesman for House Minority Leader John Boehner.
"The Leaders expect all House Republican members to comply with the moratorium," the spokesman, Michael Steel, said in an email. "There will be situations where we have some confusion on how these rules are implemented, but if Members are deliberately breaking the rules, it will be a serious matter and one that the Steering Committee will consider."
Cao sits on three committees, and is the deputy ranking member on the Homeland Security Committee. Paul sits on two committees, and is the ranking member on the Financial Services subcommittee on Domestic Monetary Policy and Technology. Young is the ranking member of the Resources Committee and sits on two other committees.
You can see Cao's requests, including $45 million for the Army Corps of Engineers to mantain levees, here.
Paul's office told the Times-Picayune that, because he believes the federal government takes too much money from citizens, he considers it his job to get back as much as possible. You can see his earmark requests here.
Young said in a statement that he wouldn't comply with the ban. "I am elected to serve my constituents, and as long as they continue to request federal funding for their projects of interest, then I will continue to do my best to accommodate them," he said. Young's requests are here (PDF).