Still can't get a full Prime - Part II

[robmaxfli]

In case you need to refresh : pump-will-not-prime-i-ve-tried-the-basics-t12473.html

Current status: pump is sucking some water but not enough to get a full prime or register any pressure on my gauge. I can see a few bubbles comng out of the returns.
I hired a "Pro" to come look at it. He took the pump apart and checked the impeller, lubed all of the O-rings, checked for any leaks around the plumbing. Bottom line: he's not sure why there is low pressure. He thinks that the suction line is either blocked by something or it is leaking. He offered to blow it out but he doesn't do leak detection. I have tried the "drain king" on both ends of the suction line to no avail.
Anyone have anymore DIY advice?

thanks Rob

 

[duraleigh]

Rob,
So it was pumping normally while you were vacuuming, you stopped vacuuming and then the pump would not prime?

How did it lose prime? How far above the pool water level is your pump? How long are you letting it run before you give up? Do you have more than one suction side pipe coming to the pump drom the skimmers/drain and, if so, can you shut them off individually?

 

[robmaxfli]

Yes - it was pumping normally while vacuuming. After a while, I noticed weak suction in the vacuum head, the filter pressure was up to about 30 lbs. and there was weak water flow through the sight glass - all of this being pretty normal in my experience. I then removed the basket to clean out all the junk. I also stuck my hand in there to remove some grass/twigs in the impeller. I turned the pump back on and this is where I am at now.
The pump is just a couple of feet above the pool water.
I have let it run a full 5 minutes before giving up. I'm used to a pretty instantaneous prime in the past.
I only have the one suction side pipe coming from the skimmer.

thanks

 

[duraleigh]

the filter pressure was up to about 30 lbs.

Rob,
A filter psi increase would indicate blockage on the pressure side. Perhaps an obstruction occurred after the pump. I can't figure out how that's possible just yet but an obstruction on the suction side of your pump (including the pump basket) would've lowered the psi rather than raise it.

 

[robmaxfli]

In all the times that I have vacuumed the pool I have noticed that the pressure rises to about 30 psi after having vacuumed for a while. Once I noticed that it is not vacuuming well I check the gauge and it usually at around 30psi. I then usually backwash at that point and it comes on back down.
On another note, I can start fresh with a clean, broken down filter , vaccum the pool for 30 minutes and have the pressure come back up tp 30 in that amount of time (yes- with there being a lot of dirt/leaves on the bottom).

 

[duraleigh]

30psi is pretty darn high. Which is why I suspect some blockage on the pressure side. That pressure side blockage could be the issue that's preventing you from priming......even tho the cause is usually on the suction side. What is your normal psi? I assume guage drops to zero when you turn off the pump.

Tell us those two answers and I'll have something for you to try that may work.

 

[robmaxfli]

With a clean filter my starting psi is 8. Yes the gauge would go back to 0 when turning it off.

 

[duraleigh]

That's a very big difference from clean to dirty. You would be far more efficient in your vacuuming and filtration if you backwashed before psi reached 20.

Okay, try this ti prime your pump. By far this is easiest with two people.

1. Turn pump off and open pump basket lid

2. take a 5 gallon bucket of pool water and begin to pour it into the basket.....try to keep the basket almost full as the water runs out the suction line back to the pool.

3. The instant the bucket runs out, very quickly get the lid back on the pump strainer basket......this is where a partner should do it before you even put the basket down.

4. The instant he has the pump basket lid on, turn on the pump.

The total time between you topping off the pump basket and the pump coming on needs to be quick, quick, quick. The idea is to evacuate all the air you can out of the suction line. My pump is 4.5 feet above the waterline and that's about the only way I can get it to prime.

I have no idea what caused it originally and I hope you don't have to do this everytime......it's a PITA.

Hope that works....it's my only idea

 

[robmaxfli]

Thanks for following this thread with me.

I tried what you said and sorry to report it did not prime.

 

[newnick]

Is the lid tight on the basket, o-ring still in place?

I just read the previous post, duh.

 

[stev32k]

It sounds to me like the suction line is partly plugged. You can try this: remove the cap on your pump strainer and if the inlet is large enough insert a garden hose as far down as it will go. Turn on the water and see if you can flush out the suction line. While the water is running you should be able to watch the skimmer and see if anything comes out. If the hose will not go though the suction line you can buy a stopper like fitting that the hose screws into and it covers the opening. When you turn on the water it will pressurize the line and may dislodge the plug.

If the suction line is cracked or broken it can be relined, but that is not a DYI project. To determine if you do have a broken or cracked line plug the hole in the inlet skimmer and fill the pump inlet strainer with water. If the skimmer plug is tight the water level in the strainer should not go down.

 

[robmaxfli]

Quick ? about the plugs for the skimmer" Can they be bought at a hardware store? What size and thread would they be?
thanks

 

[stev32k]

Quick ? about the plugs for the skimmer" Can they be bought at a hardware store? What size and thread would they be?
thanks

I used a tapered No. 10 rubber stopper. Something I had left over from my laboratory days. You can buy them on-line or you might be able to use a sink stopper with some heavy weight on top - like a stack of bricks or maybe just a piece of plastic or rubber weighted down with bricks. There is not going to be a lot of pressure needed to seal off the inlet so you can try several things.

 

[duraleigh]

Rob and steve,

I have tried the "drain king" on both ends of the suction line to no avail.

It sounds like you have already attempted to clear the suction line. If I am confused as to what you are currently discussing, disregard this post, I'll figure it out.

 

[robmaxfli]

Yes - I have attempted to clear it on both sides. I haven't blocked it off at the skimmer, filled it and then watched the level of the water in the basket - to see if water is leaking :? .

 

[robmaxfli]

I hired a leak detector to come out and do his thing. He can't find any leaks in the plumbing. He was able to get a full prime by blowing air into the other hole in the skimmer line ( that is connected to the drain). he said that a bunch of junk came out of the drain when he did this. He then turned on the pump and it is fully primed. The only worry that I have is that the filter is only registering 4.5 psi of pressure and the returns are not pushing water as fast. I am used to 8+ psi at start up (filter just cleaned). Any advice about the pressure?

 

[duraleigh]

Any advice about the pressure?

You have a partial blockage somewhere on the suction side.

Unclogging the connecting line between the skimmer and the main drain would seem to have little, if any, effect. I can't help but think he partially dislodge the blockage brom the skimmer to the pump and some of it is still left.

 

[robmaxfli]

Ok one last thought. The filter started out at 5 psi at 4:30pm... By 8pm the psi was at 23...Is it normal for a filter to rise that far in that amount of time? Yes the water is cloudy but its no swamp...