Do not start by adjusting the pressure switch. First decide whether the pump has water, whether it can prime, whether a fixture is open, and whether pressure is escaping somewhere.
1. Make sure the pump has water
Confirm the fresh tank has water above the pickup level and the tank drain is closed. If the RV is tilted, a low tank can uncover the pickup. Return winterization valves to normal tank mode and close any siphon tube used for antifreeze.
2. Open a faucet and purge air
Open the nearest cold faucet and let the pump run briefly. If it spits air and then steadies, continue purging other fixtures. If it never produces a steady stream, read RV water pump runs but no water comes out.
3. Inspect the inlet strainer and suction side
A loose strainer bowl, missing O-ring, cracked inlet fitting or loose swivel connection can let the pump pull air without leaking water. Clean the strainer, seat the gasket and tighten by hand as the pump manual allows.
4. Close every water outlet
Check sinks, shower, outside shower, toilet valve, low-point drains, washer hookups, ice maker, spray ports and water filter housings. An outside shower with both knobs open can cause strange pressure behavior even if the wand button is off.
5. Look for leaks while the pump runs
Use a flashlight and dry tissue around fittings. Check under sinks, behind the water heater, around the toilet, near the pump, at filter housings and under the RV. If the pump runs continuously and water appears anywhere, turn it off and fix the leak before testing again.
6. Consider pump check valve and pressure switch issues
If the plumbing is closed, no leak is found, suction is airtight and the pump still never shuts off, the pump may not be reaching shutoff pressure or the pressure switch may not sense it. Internal check-valve debris can also let pressure bleed backward.
7. Do not overtighten the adjustment screw
Some pumps have adjustable pressure switches, but adjusting blindly can mask a leak, overpressure the system or make cycling worse. Use the pump manufacturer's procedure and specifications.
Related plumbing pages
- RV water pump keeps cycling
- RV water pump runs but no water comes out
- Fresh water tank filling on city water
- Finding hidden RV plumbing leaks
- RV toilet repair guide
FAQ
Why does the pump run after I winterized?
A winterization valve may still be set to the siphon line, the fresh tank pickup may be closed, or air may remain in the lines.
Why does the pump stop only when city water is connected?
City water is supplying pressure that the pump cannot build or hold. Diagnose the pump, suction side, tank supply and leaks.
Can a toilet cause the pump to run nonstop?
Yes. A leaking toilet valve or bowl seal problem can keep pressure from building or holding.
Follow the pump path
The water-system troubleshooter separates no-prime, cycling, leak and pressure-switch symptoms.
Diagnose water pumpSources and review notes
Use the installed water pump manual for strainer service, pressure-switch adjustment and replacement parts. RV plumbing layouts vary, especially around winterization valves and water management panels.