Replacement Options
The most popular way to address this issue is to simply replace the CP4 with a CP3. Many companies, such as Fleece, BD Diesel, and Dynomite Diesel offer replacement kits that come with everything you need to change out the offending CP4 with a stronger, more reliable CP3. Some companies even offer the solution of a dual fueler kit, which is simply a CP3 that sits alongside the CP4 to help out with pumping duties. This is more popular with Power Strokes, though, so it may not work as well with a Duramax.