Zoeller 30-0181 check valve
$21.59 at Amazon
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See fit and limitsSump pump not working
Match what your pump is doing to the makers’ own troubleshooting charts, check the cheap causes first, and know when it’s time to replace it.
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Quick answer
Check power first: breaker, GFCI and plug. Then make sure the float moves freely.
Know next time: Liberty ALM-2 alarm$135.73 at AmazonPrice as of Oct 24, 2026, 5:30 AM EDT · low stock then
Check it on AmazonThree parts that fix or prevent most sump failures
A check valve for a pump that cycles, an alarm so the next failure doesn’t surprise you, and a replacement pump when the motor is gone. They do different jobs, so they aren’t scored against each other.
Liberty ALM-2 alarm
$135.73 at Amazon
Check it on AmazonPrice as of Oct 24, 2026, 5:30 AM EDT · low stock then
See fit and limits
Zoeller M98 pump
$321.49 at Amazon
Check it on AmazonPrice as of Oct 24, 2026, 5:30 AM EDT
See fit and limitsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Before you touch it: power and water
A sump pit is water next to a 120 volt plug. Wayne’s manual starts its troubleshooting with two warnings.
Water near outlets or the panel
Don’t wade in. Turn off power at the breaker only if you can reach it from a dry spot, or call an electrician.
Unplug before you reach in
Wayne says to always disconnect the pump from power before servicing or adjusting it.
Let it cool for 2 hours
Wayne says submersible pumps contain oil that gets hot and pressurized, and to let the pump cool at least 2 hours before servicing.
It may restart by itself
Wayne notes the motor has an automatic-reset thermal protector, so an overheated pump can start again without warning. Unplug it first.
What is your sump pump doing?
Pick the symptom. The causes and fixes come straight from Wayne’s sump pump troubleshooting chart.
Possible causes: water level too low to lift the float, blown fuse or tripped breaker, low supply voltage, switch failed or stuck, inlet screen clogged, motor failed.
Check the breaker and GFCI, make sure the float moves freely and the inlet screen is clear. If it hums but doesn’t pump, or nothing happens with power and a free float, Wayne’s chart says replace the switch or the pump.
| Symptom | Possible causes (Wayne) | What to do |
|---|---|---|
| Won’t start or run | Water level too low to lift the float; Blown fuse or tripped breaker; Low supply voltage; Switch failed or stuck; Inlet screen clogged; Motor failed | Check the breaker and GFCI, make sure the float moves freely and the inlet screen is clear. If it hums but doesn’t pump, or nothing happens with power and a free float, Wayne’s chart says replace the switch or the pump. |
| Starts and stops too often | Water running back down the discharge pipe; Check valve missing, leaking or stuck; Switch failing | Wayne’s chart says to install a check valve if there isn’t one, or remove and inspect the one you have, and replace it if it doesn’t open and close freely. |
| Won’t shut off | Switch stuck or failed; Something holding the float up; Discharge pipe blocked; More water coming in than the pump can move | Unplug it, clear anything touching the float, and check the discharge pipe for a blockage or freeze. If the pit really is filling that fast, Wayne says to recheck the pump’s sizing. |
| Shuts off and restarts on its own | Overheating: water too warm, low voltage; Discharge pipe blocked; Switch obstruction (trips the thermal protector) | Wayne says its pumps shouldn’t pump water above 77°F, and to clear switch and discharge obstructions and have an electrician check voltage. |
| Trips the GFCI | Bad GFCI outlet; Bad pump | Wayne’s chart lists two causes: a bad GFCI, which an electrician should replace, or a bad pump. Plug a lamp into the GFCI to tell which. |
| Noisy or vibrating | Worn bearings; Broken impeller; Discharge pipe fastened too tight or too loose to the house | Worn bearings or a broken impeller mean a new pump, per Wayne. If the noise is the pipe banging, Wayne suggests a rubber coupling to isolate vibration. |
From the troubleshooting chart in Wayne Water Systems’ sump pump installation manual 600002W-001-J, read Oct 23, 2026. Wayne’s chart covers its own pumps; the same causes apply to most submersible sump pumps, but follow your pump’s own manual.
Start with power and the float switch
These are the first two lines in Wayne’s chart for a pump that won’t start, and the easiest to check.
- 1Check the breaker
A tripped breaker or blown fuse is on Wayne’s list. If it trips again, find out why before resetting it again.
- 2Check the GFCI
Wayne wants sump pumps on a GFCI and warns that GFCIs in damp areas can trip, shutting the pump off. Press reset. Plug in a lamp to confirm power.
- 3Look at the float
Wayne lists a switch obstruction and a stuck switch. Make sure nothing, from the pump cord to debris, keeps the float from rising and falling.
- 4Lift the float by hand
With the pump plugged in, raise the float (or pour water in). It should start. If it hums but moves no water, look at the inlet screen and impeller.
- 5Check the inlet screen
A clogged inlet screen is on Wayne’s list for a pump that won’t run. Unplug it, lift it out and clear the screen.
Zoeller sells its pumps with an LED plug that lights when power reaches the pump, which makes the first check a glance. On any pump, a plug-in lamp in the same outlet tells you the same thing.
If the float is a tethered type that swings on its cord, make sure it can swing freely without touching the pit wall. Our float switch types guide shows how vertical and tethered switches differ.
A pump that starts and stops too often
Wayne’s first cause for short cycling is water falling back into the pit from the discharge pipe.
Every time the pump stops, the water standing in the discharge pipe drops back into the pit unless a check valve holds it. That refills the pit and starts the pump again, over and over, which wears the switch and motor. Wayne’s manual requires a check valve on its pumps for this reason.
If you have one and it still cycles, Wayne says to remove it and check that it’s installed the right way and moves freely, and to replace it if not.
Zoeller adds one more rule: with a check valve, drill a vent hole of about 3/16 inch in the discharge pipe below the check valve and pit cover to let trapped air out. Our sump pump check valve guide and weep hole guide go deeper.
Zoeller 30-0181: the check valve
A 1-1/2 inch PVC check valve with slip unions, for the pump that cycles.
The 30-0181 is Zoeller’s 1-1/2 inch PVC check valve, and I’ve used it. Zoeller’s listing says it has slip-by-slip unions, a flapper that bends over a radius instead of a sharp 90° edge, and can go in vertically or horizontally. It’s designed to reduce water hammer, the bang when a check valve slams shut.
Zoeller lists it for 4.3 psi, which is 10 feet of head, at 130°F. If your pipe climbs more than 10 feet above the valve, check that rating against your lift.
The unions let you take the valve out without cutting pipe, which makes the next pump swap easier. Put it where you can reach it, and drill Zoeller’s 3/16 inch vent hole below it.
Where it helps
- Stops discharge water falling back into the pit
- Unions for easy removal
- Vertical or horizontal mounting
What to watch
- Rated 4.3 psi (10 ft of head) at 130°F
- 1-1/2 inch only
- Needs the vent hole below it
Liberty ALM-2: the high water alarm
An indoor alarm with its own float on a 20 foot cord, so you hear about a failure before the floor does.
My call: a pump that fails tends to do it when it’s working hardest, in a storm. An alarm with its own float turns that into a warning, and I’ve used this one.
Liberty’s documents describe the ALM-2 as an indoor alarm on a 115 volt supply with a 9 volt battery backup, and a tethered float on a 20 foot cord. The ALM-2-1 is the same alarm with a 10 foot cord. Liberty calls these narrow-angle sensors.
Set the alarm float above the pump’s normal switch-on level, so it only sounds when the water rises past where the pump should have started. The battery powers the alarm, not the pump; for that, see our battery backup guide. More alarms are in our sump pump alarm guide.
Where it helps
- Warns before the pit overflows
- 9 V backup keeps the alarm working in an outage
- 20 ft cord reaches a dry wall
What to watch
- Indoor use
- The battery doesn’t run the pump
- Local alarm only; no phone alerts
Zoeller M98: the replacement pump
When the chart says “replace pump,” this is the one I’d put in.
Wayne’s chart ends several rows with “replace pump”: a failed motor, worn bearings, a broken impeller, a pump that trips a good GFCI. When you get there, the Zoeller M98 is my pick, and I’ve used it. Our sump pump guide has its full specs and three alternatives.
Before you buy, write down two things from the old pump: the discharge size, so the new one fits your check valve, and the switch type, vertical or tethered, so it fits your pit. Take a photo of how the old pump sits and where the float swings before you lift it out.
Where it helps
- Drop-in replacement for most 1-1/2 inch discharge pits
- Cast iron, per Zoeller
- Full comparison in our sump pump guide
What to watch
- Match the discharge size first
- Match the switch type to your pit
- Recycle the old pump’s oil-filled motor properly
Specs from Zoeller’s 30-0181 listing and Model 98 data sheet FM2779, and Liberty’s ALM literature and manual. Offers read through the Amazon Creators API on Oct 23, 2026, 2:22 AM EDT: all three new and in stock.
Which part fixes which problem
Match the part to the symptom.
| Part | Key specs | Fixes | Pick it if | Skip it if |
|---|---|---|---|---|
| Zoeller 30-0181 check valve | 1-1/2 inch slip unions, 4.3 psi (10 ft) at 130°F | Short cycling | The pump starts and stops too often or you have no check valve. | Your lift above the valve is over 10 feet. |
| Liberty ALM-2 alarm | 115 V with 9 V backup, 20 ft float cord, indoor | Surprise failures | You want warning before the pit overflows. | You need phone alerts when you’re away. |
| Zoeller M98 pump | 1/2 HP cast iron, 1-1/2 inch discharge | A dead or worn-out pump | The motor, bearings or impeller are gone. | The problem was power, the float or the check valve. |
When to replace the pump instead of fixing it
Wayne’s chart is blunt: several symptoms only end one way.
| Sign | Wayne’s suggested remedy |
|---|---|
| Motor won’t run with good power and a free switch | Replace pump |
| Worn bearings or a broken impeller (noise, vibration) | Replace pump |
| Pump trips a known-good GFCI | Replace pump |
| Switch failed | Replace the tether switch or replace the pump |
| Thermal protector keeps tripping | Clear obstructions, check voltage; Wayne notes it can also mean end of product life |
Wayne also notes that its pumps use dielectric oil for cooling and that you should follow state environmental rules when disposing of an old pump. Don’t just toss it in the trash.
If you replace the pump, replace a tired check valve at the same time, and add an alarm if you don’t have one. A new pump with an old stuck valve will short cycle from day one.
Sump pump troubleshooting questions
Why is my sump pump not turning on?
Wayne’s chart lists: water too low to lift the switch, a blown fuse or tripped breaker, low voltage, a failed motor or switch, a clogged inlet screen, or something blocking the switch. Check power and the float first.
Why does my sump pump keep running?
Per Wayne: a stuck or failed switch, something holding the float up, a blocked discharge pipe, or more water coming in than the pump can move.
Why does my sump pump turn on and off every few minutes?
Usually water falling back from the discharge pipe. Wayne says to install a check valve, or inspect and replace a leaking one.
Why does my sump pump keep tripping the GFCI?
Wayne lists a bad GFCI or a bad pump. Plug a lamp into the GFCI to tell which; if the lamp trips it too, call an electrician.
Can a sump pump overheat?
Yes. Wayne says its pumps shouldn’t pump water above 77°F, and the thermal protector trips on overload, low voltage or a blocked discharge.
How do I test a sump pump?
Pour water into the pit or lift the float by hand with the pump plugged in. It should start, empty the pit and stop. Wayne also recommends testing through several cycles after installation.
Why is my sump pump so loud?
Wayne lists worn bearings or a broken impeller, which mean a new pump, or discharge pipe fastened too tight or loose; a rubber coupling isolates vibration.
Do I need a check valve on my sump pump?
Wayne requires one. Zoeller says to drill a 3/16 inch vent hole below it.
Why trust PlumbingPicks?
Isaac Daniels is a licensed journeyman plumber in Georgia and has used all three parts. The causes and fixes on this page come from Wayne’s and Zoeller’s own installation manuals; where we add advice from the trade, we say so.
How we pick
We picked one part for each common failure: a check valve for cycling, an alarm for warning, and a pump for when the motor is gone. They do different jobs, so they aren’t scored against each other. Each was new and in stock on Amazon when we checked, Oct 23, 2026, 2:22 AM EDT.
Sources
- Wayne Water Systems, sump pump installation manual 600002W-001-J, including the troubleshooting chart (waynepumps.com): read Oct 23, 2026.
- Zoeller, installation instructions FM2676 (0726), Model 98 data sheet FM2779 and product pages (zoellerpumps.com): read Oct 23, 2026.
- Liberty Pumps, ALM alarm literature LLIT006639 and manual 2138000 (libertypumps.com), as recorded Oct 20, 2026.
- Zoeller, 30-0181 check valve, brand-written Amazon listing: read Oct 23, 2026.
- Amazon product data for B0009WD1L4, B002YSAVHS and B000TK5ULA, read through the Creators API on Oct 23, 2026.
- Google results for “sump pump not working”: seen Oct 23, 2026. Search volume from Semrush, Oct 22, 2026.