I have a 2015 Chaparral 270 Signature with the DPS -B outdrive. The drive won't stay trimmed up while on plane. It will go up but drops back down within a few seconds while under load. The drive will stay up indefinitely while on trailer or sitting in the water. I have replaced the trim pump as we suspected that the check valve within had gone bad allowing fluid to flow back into pump while under load. Drive is still falling even with new trim pump installed. I don't see any oil sheen on water indicating a leaking trim cylinder. Any suggestions on where to look next or how to test the cylinders? Thanks in advance!

 

I suspect it's leaking between the top section and bottom section of one or both trim cylinders. Hopefully you can get a trim cylinder seal kit and install it. Look for any damaged or corroded parts that would prevent a good seal. The trim pump pushes trim fluid to the top of the cylinder or to the bottom. The trim pump motor and go in either direction to pump.