Moved water pump...now it's acting strange!

[Acampingwewillg]

OK....I have the Shur-flo variable speed 5.7 pump, have had it for many year's now. The location of the pump was in such a confined space(under the vanity sink and it has leaked before making repairs difficult. So after putting a new sub floor down, I decided to move the pump so that I can watch it more carefully and quickly make repairs(fix leaks). So I added about 6-7' of hose, turn it on and bled out the air. It all goes well until the pump shuts down, I can watch the water start to flow backwards and the pump will start back up but will not pick back up the prime(it sounds like its just spinning dry). I can turn a faucet back on and it will start pumping again.

I didn't have this issue before moving it...my only thought now is maybe adding a "check valve " in line close to the pump in-let? They do have a built in check valve, correct? I think I do recall that this particular pump may have had some issues with the strainer basket prior to entering the pump...anyone recall that problem? Anyways...open for idea's or suggestions?

[All_I_could_aff]

Don't feel dumb...
Feel smart for figuring it out before paying someone else to!

[Acampingwewillg]

OK....I feel pretty dumb! After getting everyone's idea's here, I decided I'd pull it back apart, lower it back down to floor level, put a check valve in I had laying around and give it a try. Make a long story short, it worked better, no dry running but after pumping water and shutting down a faucet, 15 seconds later it would run real slow, then stop, then real slow then stop. I thought to myself, "can I live with that"? I decided No, so as I was preparing to re-install it in it's original location, (this is the dumb part), I checked my "black tank" flush valve that is in the same location as the pump was at first. I must have turned on the flush to relieve pressure when I first moved the pump. I close the valve completely, thanking goodness that I didn't start taking it all apart again....and low and behold, it's back to working perfectly in its NEW location and NO leaks. Thanks everyone!!!

[DutchmenSport]

I read your post and my very first though was, you've go a leak between the tank and the pump. But, someone else already beat me to that idea.

[Acampingwewillg]

Air leaks and water leaks checked but as mentioned and a thought I had is that I did raise the vertical height of the pump about 12", so although the original location of the pump was above the water tank, it was in very close proximity to it. Guess I'll lower it back down to floor level and see what happens. Thanks everyone!

[3oaks]

I would suspect either an air leak in area of the pump or a bad check valve at the pump.

[Ozlander]

deleted

[Ozlander]

Air leak. Tighten the hose clamps.

[allenm]

If you have a sediment filter on the intake, you might double-check it. I always have trouble getting mine tight enough not to leak air, then it won't prime.

[enblethen]

Did you check polarity on the power?

[Farmerjon]

WyoTraveler wrote:
Is the pump at the same vertical height as it was before? Some pumps have pressue to push water at high pressure but not enough suction to draw water up into it. Lookng at large scale pumps like well pumps. They can draw water from deep wells of hundreds of feet and push out under pressure but other large pumps like ditch pumps can only raise water a very few feet but can push it out under high pressure. Since most pumps I have seen in RVs seem to be mounted almost level with the bottom of the tank I suspect they can push water out with pressure but limited to how far they can raise water into the inlet of the pump. Seems to me if you just added extra water line and didn't raise the pump vertically it should operate the same providing there are no leaks in the fittings or water line

X2
If it is a centrifugal pump it has to be mounted below water level.

[WyoTraveler]

Is the pump at the same vertical height as it was before? Some pumps have pressue to push water at high pressure but not enough suction to draw water up into it. Lookng at large scale pumps like well pumps. They can draw water from deep wells of hundreds of feet and push out under pressure but other large pumps like ditch pumps can only raise water a very few feet but can push it out under high pressure. Since most pumps I have seen in RVs seem to be mounted almost level with the bottom of the tank I suspect they can push water out with pressure but limited to how far they can raise water into the inlet of the pump. Seems to me if you just added extra water line and didn't raise the pump vertically it should operate the same providing there are no leaks in the fittings or water line

[SoundGuy]

Acampingwewillgo wrote:
Anyways...open for idea's or suggestions?

Yes, your pump does have a check valve in the head and it should not have any difficulty priming and maintaining that prime with just 6' of extra hose on the input side. The fact you are having this problem suggests the connection(s) may be leaking and if so could be solved by using hoses with factory assembled 1/2" NPT fittings, an example being those offered in this SHURFlo Pump Silencer Kit ... each hose is 3' long and the two can be barreled together to make up a 6' length.