When pump is on Bypass, water comes out strong through both inlet jets into the pool, but if pump is on normal (Filter), nothing comes out at the 2 jets. Water in the pump basket even drops somewhat.

possible debris in air inlet

are there shut off vavles you may have overlooked after the the filterpump?

Thank youfor posting your question here on Fixya.com. When a pump is shut off it gives the sediment in the filter a chance to become suspended in the water and not on the filter cartridge surface. When you turn the pump on this dirt does non restrict flow as much because it is not all on the filter and then it starts to collect there restricting again the flow. For this reason when this happens the filter cartridge needs to be removed and cleaned off with water from a hose with a spray attachment. The attachment should be set to a single strong jet. Once the filter is reassembled check to see how long it can go without reducing flow. I think you will be surprised.
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Below is a link to the users manual for these pool filters. It has a troubleshooting guide that might help you figure out the problems that you are having with your filter. Hope this helps.

http://www.backyardcitypools.com/images/hayward/pro-series-manual.pdf

NOT THE MOTOR ,THE SEAL... JET PUMPS ARE NOT FOR POOLS.. LOW FLOW HIGH PRESSURE.. YOU NEED HIGH FLOW LOW PRESSURE ... IF NOT YOU MAY HAVE A SUCTION LEAK OR A BAD SHAFT SEAL... VOTE JAY

Remove your filter cartridge and test again. If flow is still low, then check for debris plugging the inlet to the pump. If removing the cartridge resolves the flow issue, then clean the filter or replace it.

I have a 16 x 48 intex pool with the 1inch inlet and outlet. I purchased the intex 4000 pump. The attachments are too big for the inlet and outlet so i then purchased the adapters. The plungers are very noisy and allow air to get into the pump. I removed them and hooked the hoses up to the adapters directly. That worked as long as the adapters were new. This year the seal comes loose and allows air to get into the pump. I even tried allowing the top nut to be loose to allow air to escape. This year nothing works. The pump is just too strong for the holes. I was considering cutting the holes bigger and glueing seals on there but i was concerned about creating weak spots in the pool. I am tired of spending money on it so i did the redneck thing. I can say that because well, you might consider me one. I took the inlet hose off the connector and plugged the hole with one of those little black things. I took the hose and run it up through the hole in between the liner and the poles and down into the pool. If you run it over the top it will not work correctly. Take the hose and tie them together between the two sides as best you can to keep the hose in the pool. If you look at the smaller intex pools that dont have holes, that is how they have the pump hooked to the pool. VOILA! You have an airtight inlet to the pump. You do not need to do that to the outlet because its not sucking water its just pushing it. So, just hook the hose up as you wish. When you need to clean the filter, I put wash clothes in the hoses to plug them and voila. No air gets into the filter. Done! It is actually keeping my pool clean this year. Also, i purchased one of those aqua vacuums and it does work great for this pool. Once you get the big stuff, sweep it with a pool broom and the filter will do its job. You can vacuum these pools with the filter type pumps. Next time, i will purchase a sand filter and be done with it. Happy swimming with less work.

ok -
1. go to k-mart or pool shop and get yourself some pool socks.
Pool socks fit over your skimmer filter and will filter out smaller bits before going into your filter system - very good to use when 'vac'ing your pool when there are lots of particals in your pool.

2. If you have a sand filter system - you will have a control handle some where on your pipe work near your filter, which will have around some settings you can select with handle... like....> Normal, backwask, rinse, recirculat + others PLUS a pressure guage.

If you do have this sytem - 'vac' your pool on Normal - then when finished OR pressure builds - back wash - rinse - then back to normal.

sorry about spelling :)

you could have a leak in the vac hose or a shaft seal on the pump, if there is a wet spot under your pump there is a good chance the shaft seal is BAD.... some pumps are so strong you can starve the PUMP for water, the trick is to set your valve more towards the main drain./ hope this helps.. i'm your local pool pump motor repair guy