Question
HELP! I installed a 2hp Berkeley SSHM-2 multi-stage pump.  My furthermost head/zone is 325 away with 40 ft. elevation.  It is not working properly.  The zone will run for a few minutes and then lose pressure/flow to the point of not working at all.  I have the ability to switch to a city water system and the system works fine so therefore I do not think it is a valve issue.  My flow at the pump with a zone running is about 12-15gpm.  I don't think there are any obstructions, water is relatively clean, intake not laying on bottom of pond. Pump too small?  Thanks for your help.

Answer
Good question.
Your distance, elevation and GPM are all correct. Thank you for the complete information.
I'll say my usual with pump problems. Check for suction air leaks. Other than that the best guess I can give is the lake filter is getting partially plugged in the pond. Once the zone shuts down the obstructions drop off the filter. Have you went into the pond while the system is running and watch the filter? It could tell you a lot.

The other possibility is: The SSHM-2 pump has had some difficulties with spinning it's internal casing under higher pressures. If it has ever gotten hot while running I would suspect this. To check this, you will need get the pump primed, then run it with just a tiny bit of water flowing. About the flow of 1 sprinkler. It isn't going to blow-up. You then need a pressure gauge on the discharge of the pump. With one 2-3 GPM sprinkler you should see 85+ PSI. If it is much less than 80PSI it has an internal problem or you filter is completely plugged.
Try these suggestions and reply back with the results.

Matt