Fx5 pump pulsing problem

[robdog013]

I have a problem with my fx5 the motor is pulsing and doesn't sound right I have pulled it apart and cleaned and it has a new impeller. It is an fx6 motor on an fx5 body. When I run the motor when it is not attached to the body is spins freely but is a bit noisy. If any one has any advice on how to fix that would b awesome. The motor sounds like it's pulsing

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[Ageofaquariums]

Firstly check all piping and make sure theres no blockages. Then check internal circles of your media baskets, there should not be fine mechanical filter media in there. You have the outer part of the media baskets that come with the coarse sponge pads, these are your mechanical filtration.....  the inside ones need good water flow. If you need to add chemical filtration in a fine bag, ensure you cram some bio balls or something beside it so water can bypass IF the bag gets blocked. Next thing to check is the underside of the lid, theres a hard plastic straw. This needs to be clear. Blast it out with garden hose. Check these things first and make sure they are OK. We kinda want to check all alternatives before we go down the "pump is broken" route.

 

[robdog013]

I have checked all pipes, and cleaned the impeller, even the little straw on the underside of the lid. I have only filled this filter with sponge in every basket as this is a supplementary filter. I already have another fx5 with bio and a 3ft sump full of mechanical and bio. After cleaning I re assemble and fill Galway with water to test l. The pump is already pulsing and it squirts water similar to a heart beat. At this stage there is no noise coming from the motor. When I reassemble fully and connect to my tank and turn on the motor pulses and then with every pulse makes a sound like the impeller is rubbing on somethin. I lean the filter on a 45 degree angle and the sound stops but the motor continues to pulse and micro bubbles are expelled. There is no 1 min stop after turning on to expel air which tells me there might be a problem with the chip. Surely someone has seen this happen with the fx5?

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[Ageofaquariums]

Why fill it half way after setup? thats a lot of air for it to have to spurt out. I recommend assembling the canister with no water in it. Making sure the outlet nozels are above the surface of the water, hold the quick click end of the outlet hose over a bucket. Turn the flow on it and drain ALL the water out of the outlet hose into the bucket. Once outlet hose is empty attach it onto the FX5, keeping the flow totally open. Now attach the intake hose to the FX5 and then turn its flow to full. Because the intake hose is totally full of water it should syphon into the FX5, and because the outlet hose is empty, the air in the FX5 should have no problem escaping through it. Once the FX5 is completely filled with water, plug it in. If you are still having surge issues, its the motor. I dont recommend having any sponge in the internal baskets as it puts a lot more strain on the motor, and makes it very difficult for air to purge. Usually the FX5 is such a beast it just powers through it....  but yea, not always.

[Ageofaquariums]

Just another thought, what condition are your O-rings in? I imagine the motor one is brand new, but the main O-ring and the click fit connection ones? Just if they are perished and its sucking air, its also going to cause pulsing. The lack of leaking tho, means this is unlikely but I thought I would mention.