pump wont prime in filter mode

Jun 23, 2014
5
Bentonville, Ar.
I've lived in my current house about 12 years, lots of experience trying to get my pump to prime and understand the do's and dont's. The problem im having this year is my pump will prime fine if its in backwash or waste or rinse mode but when its in filter mode, it has water coming through ok, just not enough to create suction for my vacumn. Doesn't matter if i have only main drain open, or skimmers open or both, just seems like water flowing through isnt as strong in filter mode. I replaced all the sand and checked the innards on my filter at that time. Also replaced my multi-port valve because there was a tiny bit of leakage around the seal and it was 16 years old. Did all that and still have the same issue. I can visibly look at all plumbing and see no leaks from the pump to filter or any return valves. I do see a tiny bit of water under my filter like it has a leak, but i cant see where it is and would that be enough to cause no this since i do have good pressure/prime when i have filter in backwash or waste mode? I have checked all the plugs in the pump and filter also and added an 0 ring. Not sure what else to check, to get it to prime in filter mode, obviously seems like air leak but not sure where it would be since its ok in backwash mode.
 
The conditions you are reporting are quite puzzling. The position of the multi-port should have VERY little affect on the pumps ability to prime.

How do you get your pump to operate? Do you prime first in another mode and then switch to filter?

What is your psi when the pump is off?

What is the psi when your pump is in filter but not priming properly?

What is your psi with the pump in "backwash" mode?
 
i'll have to check the psi in each of those positions, I haven't really paid attention. I normally just prime it in the filter mode. I did all of the backwashing and rinsing because i was opening the pool, then ended up replacing the sand, so backwashed/rinsed it also. Always primes right away in those modes, switch it to filter or recirculate and it wont prime. I get enough water circulating to run my pump and filter my water, but just cant vacumn in filter mode.
 
Ok so i found a leak, 2 inch crack on bottom o f filter, got a new filter, installed int along with new multiport valve, still no suction in filter mode, 10 psi in backwash and rinse mode , 15psi in filter or recirculate mode, makes no sense, pmenty of suction/prime in backwash rinse or waste, not filter or recirc
 
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