An RV water pump that will not start is usually a power fault: the switch, the fuse or the 12-volt supply. One that will not stop is usually a leak or trapped air on the outlet side. The pump makers' troubleshooting tables begin in a different place for each symptom.
RV Water Pump Problems: No Pressure, Pulsing, Running Constantly, Not Turning On
At a glance
- Will not run: Shurflo and Remco both start at the fuse, switch and 12-volt supply, and both note the thermal protector resets by itself as the motor cools.
- Will not stop: Shurflo and Remco look for a leak on the outlet side before anything inside the pump; Flojet starts with an empty tank.
- Cycles with every tap closed: Shurflo blames scale on the diaphragm and valves from lack of sanitizing, and reserves pressure switch and by-pass adjustment for a technician.
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Start with the symptom, not the pump
Each maker's symptom table starts in a different place, so work down the list for your symptom and your pump's brand, as with an air conditioner that is not cooling.
| Symptom | Shurflo 4008 and 4048 start with | Remco Aquajet starts with | Flojet Triplex lists first |
|---|---|---|---|
| Pump will not start, or blows the circuit | Electrical connections, fuse or breaker, main switch, ground | Tripped thermal protector or blown fuse | Loose wiring connection |
| Motor runs, no water | Strainer clogged with debris | Water tank empty | Restricted intake or discharge line |
| Runs on with every fixture closed | Output side plumbing for leaks, leaky valves or toilet | Diverter valve left in fill mode | Empty water tank |
| Cycles rapidly while a tap is open | Restrictive plumbing, faucet and shower head restrictions | Hydraulic pulsations (fit a pulsation dampener) | Restricted pump delivery (listed as pulsating flow) |
| Low flow or weak pressure | Not a heading in the manual; covered by its chart | Rebel manual: leak on inlet side of pump | Air leak at pump intake |
| Leaks at the pump head or switch | Loose screws at switch or pump head | Perforated diaphragm, contact the factory | Not a separate heading |
Rows from the Shurflo, Remco Aquajet and Rebel, and Flojet Triplex manuals.
Tip: The strainer is Shurflo's first check only when the motor runs but no water comes out. For a pump that will not shut off, Shurflo starts with the plumbing on the pressure side, outside the pump.
Why an RV water pump will not turn on
Shurflo's 4008 manual starts at the electrical connections, fuse or breaker, main switch and ground, then asks whether the motor is hot, because its thermal breaker resets when cool. Remco's Aquajet manual puts the fuse and thermal protector first, then the battery or power supply, polarity, main switch and wiring. Remco also says to thaw a frozen pump before starting it, because starting it frozen can damage the pump or motor.
Jayco's Class C manual gives the coach-side fuse steps:
- Turn off the electrical components the fuse protects.
- Disconnect the shore power cord.
- Switch the inverter off.
- Remove the fuse panel cover and pull the fuse straight out.
- Fit a new fuse of the same voltage, amperage rating and type, in the same location.
Never fit a higher rated fuse: Jayco warns it can start a fire by overheating the wiring. Ratings vary by pump (Remco lists 15 A for the Aquajet RV series and 10 A for the ES series), so use the rating on your pump's label and in its manual.
Because the thermal protector resets by itself, a stopped pump can restart without warning. Disconnect power before reaching for the pump head.
The motor runs but no water comes out
Shurflo's order is the strainer, then an empty tank or air collected in the water heater, then air drawn in at the inlet connections and kinked or restricted plumbing. Remco starts with an empty tank, then an inlet-side leak, then debris under the valves, which it clears by opening every hot and cold faucet fully and letting the water run for a few minutes.
Cleaning the strainer is an owner job. Jayco's steps:
- Switch the water pump off.
- Unscrew the clear cap on the in-line strainer.
- Remove the metal screen and clear the debris.
- Reinstall the screen and cap.
Shurflo requires a 50-mesh inlet strainer and Flojet a 40-mesh one for its warranty to be valid.
After storage, check that the fresh tank shutoff valve is back on, then fill the tank, open all the faucets, switch the pump on, and close them once the water runs free of air, as Flojet's start-up describes.
Why the pump keeps running or cycles with the taps closed
Shurflo looks outside the pump first: leaks on the output side, including leaky valves or a leaking toilet, then air trapped on the outlet side or in the pump head, and last the pressure switch or by-pass. Remco starts with a diverter valve left in fill mode, then an empty tank, an outlet-side leak and an inlet air leak. Flojet's Triplex manual starts with an empty tank and low battery voltage.
With no leak to find, Shurflo points at maintenance. It calls lack of sanitizing the number one reason for premature pump failure, because scale on the diaphragm and valves causes low flow and leak back: occasional cycling with no faucets open, or the tank filling when the RV is hooked to city water.
Tip: Some cycling is normal, depending on how much water is being drawn, Jayco says. Remco's limit is no more than 6 times per minute of rapid on and off cycling, because it overheats the motor and shortens the life of the pump and switch.
| Pump | Shut-off pressure | By-pass |
|---|---|---|
| Shurflo 4008 Revolution, 12 VDC, 3 GPM | 55 psi | Begins opening about 40 psi, full by-pass about 62 psi |
| Shurflo 4048, 12 VDC, 4 GPM | 55 psi | Begins opening about 30 psi, full by-pass about 65 psi |
| Remco 55AQUAJET-AES, 3.4 GPM | 65 psi | Not published as a by-pass figure |
| Jayco installed pump (2025 Class C, 2027 towable) | Runs until it reaches 45 lbs | Not applicable |
Read the pressure for your coach off the documentation for the pump that is fitted.
Leave the settings alone. Shurflo says by-pass adjustment is for a professional technician with proper gauges, because set too far, the pump will not shut off. Remco says never adjust its demand switch without consulting the factory, and the pump must never see more than 90 psi.
Pulsing flow and weak pressure
Flojet gives one cause for pulsing flow, restricted pump delivery: check discharge lines, fittings and valves for clogging or undersizing. Shurflo's rapid-cycling list adds faucet and shower head restrictors, and a water filter that should be on a separate feed line. Remco prescribes a pulsation dampener (25-174 with elbow fittings, 25-175 straight) and a check of the inline filter.
Shurflo asks for plumbing of at least 1/2 inch inside diameter, because smaller lines cause low flow and noise, and for the pump to sit within 6 feet of the tank. Voltage matters too: Remco wants at least 11 volts at the pump while it runs, and Shurflo says lower voltage means lower flow. Pressure costs flow as well, as Shurflo's 4048 table shows:
| Pressure | Flow | Current |
|---|---|---|
| 0 psi | 4.0 GPM | 3.0 A |
| 20 psi | 3.2 GPM | 6.0 A |
| 40 psi | 1.75 GPM | 8.0 A |
| 50 psi | 0.8 GPM | 9.0 A |
Figures from Shurflo's 4048 installation manual; its product data sheet prints slightly different currents. The rated GPM is the open-flow figure, not what comes out of a shower head at working pressure.
Repair or replace
Shurflo sells repair kits for the 4008 and 4048: check valve, pressure switch, valve assembly, pump head, drive assembly and motor. Flojet lists a pressure switch and a check valve assembly as service parts.
Remco sends a faulty pressure switch, a perforated diaphragm and a faulty speed controller to the factory, and a failed motor means a new pump. Leaking inlet or outlet fittings are an owner fix: replace the O-rings or fittings. None of these manuals publishes a part price.
When fitting a new pump, size the circuit, not just the flow. Remco warns its Aquajet pumps may draw more current than the pump they replace, and undersized fuses, wires and switches can overheat and cause an electrical fire. Reversing polarity instantly blows the fuse and may damage the controller.
Check the controller as well: Shurflo and Remco both call for a 10 or 15 amp Intellitec controller. Anyone not confident with low-voltage wiring should have a qualified technician do the installation, Remco says.
How long an RV water pump lasts
No pump maker publishes a service life in years. Remco warrants its pumps for one year, two years on Aquajet pumps, and says brush wear may be limited to 1000 hours or less. Flojet warrants the Triplex for two years from date of manufacture.
These pumps are rated for intermittent duty only; Shurflo and Jayco both say continuous running shortens pump life and is not covered by warranty. Shurflo's maintenance list: clean the strainer, sanitize and winterize, and check fittings for tightness, since road vibration loosens them.
Common questions
What are common problems with RV water pumps?
The makers' tables cover five: a pump that will not start, one that runs without delivering water, one that will not shut off, rapid cycling or pulsing, and leaks at the pump head, switch or fittings.
Why does my RV water pump keep running?
Shurflo's first check is a leak on the output side, including leaky valves or a leaking toilet; Remco's is a diverter valve left in fill mode; Flojet's is an empty tank. With no leak, Shurflo blames scale on the diaphragm and valves from lack of sanitizing.
Can a leaking RV water pump be fixed?
It depends on the brand and the part. Shurflo sells kits for the valves, pressure switch, pump head and drive on the 4008 and 4048. Remco treats a leaking fitting as an O-ring or fitting swap, but sends a perforated diaphragm to the factory.
How long does an RV water pump last?
No maker states a lifespan in years. Warranties run one to two years, and the makers tie a longer life to intermittent use and regular sanitizing.