Water Pump won't prime, suggestions?

[astraelraen]

We own a 2007 Nash travel trailer we purchased last year. We have never used the pump (always used campground water) Well, I was testing the pump the other day and it doesn't prime. I can't get it to prime on a tank full of water nor can I get it to prime by putting the "winterizing tube" in a bucket of water and using that as my water source.

The pump also sounds "less loud" than I am used to RV Pumps sounding. Is there any way to check the pump or should I give up and buy a new one? I'm guessing the pump is 7+ years old.

[Harvey51]

Golden_HVAC wrote:
A new pump will solve the problem. A pump rebuild kit takes about 10 minutes to install (about the time to install the new pump) and only cost about $18.
Try the pump kit first. IT will likely solve the problem.
Fred.

Thanks, Fred! I went to an RV store and asked for a rebuild kit. The guy asked what the problem was. When I said it worked well except on priming, he pointed to the Shur Flow valve replacement, just one complicated rubber piece, for $28 CDN. I had a photo of my pump and he made sure it was the right part.

I unhooked my pump (only a couple of spoonfuls of water fell out of the pipe), opened it up and found the original "valve" looked great except for a few fragments of pipe cuttings in its grooves. The "membrane", a stiffer piece of rubber like material behind the valve looked good, too. The pump primes way better with the new valve. My tank is a foot or so below the pump and in the past primed itself only when parked on a slope to reduce that foot of height and filled the tank to overflowing. This time it self primed when level and the tank half full.

The job called for some attention to which screws go where because there are two kinds of them, course and fine threads. I recommend avoiding the temptation to take the back end of the motor housing off to look at the brushes - I had to ask for help to get it back on! The trick is to stick wires or long needles into the little holes in the plastic brush holders to hold the springs and brushes in place while putting the back end on. Tricky to get the bearing end on the shaft because it is free to tilt. My 11 year old brushes were still in great shape. No carbon in the commutator slots.

YouTube video helpful on Opening the pump: Youtube
The video refers to the black Shur flow valve as the diaphragm. The yellow/white part behind it is what Shurflow calls the diaphragm.

[FLY_4_FUN]

I once had to fill the winterizing line with water manually....then with the pump on and a faucet open I blew into the winterizing line....and away it went. The pump definitely lost prime and dried out over the winter.

Daryll

[wnjj]

The pump in our camper has been acting up for a couple of years now. Every time it sits awhile or we travel, I have to re-prime it. I've taken it apart 2 or 3 times and there is nothing in the valves and they look fine. On winterize mode it won't pull a vacuum so I fill the tube and the blow into it while the pump is running and the faucet is open. It actually takes a really hard blow to move the water at all. Once it "catches" I switch the valve back and it builds pressure fine and will work fine until the next move. Rather than fill the hose I found I can put the winterizing valve half way between and the suck water from the tank with my mouth to fill it.

In theory these pumps can run dry an indefinite amount of time but maybe a taxed it when I found it running in the shop when the water level in the tank had evaporated enough that it ran non stop. It may have been running a few weeks.

[dieseltruckdriv]

This isn't uncommon. Most likely you just need to open a faucet, it will prime itself.

[Harvey51]

I fill the tank until water shoots out the air release beside the fill port. Tank is more than a foot below the pump. I prime it by filling the winterizing tube with water, using a syrup bottle that lets me squeeze water out through a small opening.

Hmm, sounds like I need that pump kit. The RV is 11 years old.

[screaminjlew]

I've had this happen before on my trailer where the pump would just run and run without priming, what I did was open the kitchen faucet while the pump is on and that would release the air in the lines.

[enblethen]

Do you have a screen type "filter" on in in-take side? Check to make sure it is clear of any debris.
Is there water when you disconnect the in-take line?

[Chris_Bryant]

SoundGuy wrote:

Chris Bryant wrote:
A quick fix is to use a wet dry vacuum on a faucet to "pull" a prime. once primed, the pump may be fine.

Connected to a trailer's water system that's leak free any of these potable water pumps should easily prime without having to "pull" a prime.

I agree they *should*, but even a very small bit of debris in the valve body can keep it from priming. You have a choice- pull the pump, tear it down, clean it, put it back together and install.
Or you can spend a minute with a vacuum.

That's why I said "quick fix"- plus it may be another problem entirely.

[RJsfishin]

If the pump and the FWT is on the same floor/plane, the pump is already primed, if the tank is 1/4 full, and a faucet is open.

[SoundGuy]

Chris Bryant wrote:
A quick fix is to use a wet dry vacuum on a faucet to "pull" a prime. once primed, the pump may be fine.

Connected to a trailer's water system that's leak free any of these potable water pumps should easily prime without having to "pull" a prime. Since the question is whether or not the pump itself has an issue I'd disconnect it's intake and output lines from the trailer entirely and run a short hose directly from a jug of water directly to the pump intake. If the pump is functioning correctly it'll prime almost instantly, in which case you'd know there has to be a leak elsewhere in the camper that won't allow the pump to prime no matter how hard it tries.

[TucsonJim]

Chris Bryant wrote:
A quick fix is to use a wet dry vacuum on a faucet to "pull" a prime. once primed, the pump may be fine.

Wow Chris - I wouldn't have thought of that. Great idea!

[Chris_Bryant]

A quick fix is to use a wet dry vacuum on a faucet to "pull" a prime. once primed, the pump may be fine.

[BTPO1]

As said earlier check to see if all of the valves are in the proper position. Since you haven't used it in years it is possible that your suction strainer is plugged and needs to be cleaned or replaced. JMO

[Dick_B]

This problem has been discussed previously. A few suggestions: 1. be sure all the valves are in the correct position to get water from the tank and not from the winterizing line. if there is a filter upstream be sure it is not clogged. 2. turn on the pump and open all the faucets for a couple of minutes 3. reverse the inlet valves and try to get some water into the winterizing line by holding it up vertically to put pressure on the pump inlet.