Pulsing after pump head rebuild

[Chewy3925]

Just rebuilt this pump head and it was working great for a day now it’s doing this. Any recommendations? Cat 310

 

[Toms PTcarwash]

If you replaced all the seals and valves, and it started to pulsate that quickly, how did the surfaces on your brass seal cases look?
If they have any wear and are not 100% smooth, the new seals will fail rather quickly.