RV Water Pump Troubleshooting — Why Your Motorhome Pump Isn't Working

A water pump that stops working is one of the most common motorhome problems. Here's how to diagnose and fix it.

Problem 1: Pump Won't Turn On

• Power supply — Check switch panel and inline fuses. Test 12V at pump terminals.
• Blown fuse — RV pumps use 10–15 amp fuses. Check and replace.
• Corroded connections — NZ humidity corrodes wiring. Clean terminals, apply dielectric grease.
• Dead motor — Power at terminals but no spin = pump needs replacing.

Problem 2: Pump Runs But No Water

• Empty tank — Check freshwater level. Bleed air from lines.
• Blocked inlet filter — Remove and clean the mesh strainer.
• Air lock — Open the tap furthest from the pump until water flows.
• Cracked hose — Check all connections for splits, loose clamps, kinks.
• Failed diaphragm — Diaphragm cracks = lost pressure. Replace kit or pump.

Problem 3: Pump Cycles On and Off

Pump kicks on, stops, repeats with taps closed = pressure leak.

• Leaking tap or valve — Even a tiny drip causes cycling.
• Hot water cylinder — Check pressure relief valve for drips.
• Loose fitting — Tighten all post-pump clamps.
• Faulty pressure switch — Try adjusting the pump's pressure setting.

Problem 4: Noisy Pump

• Mounting — Use rubber isolators or vibration pads.
• Air in lines — Bleed by opening taps.
• Worn bearings — Grinding = replacement time.

When to Replace

Pumps over 5–8 years old with repeated issues are cheaper to replace than repair. Match: voltage (12V/24V), flow rate (8–13 L/min), pressure (20–45 PSI), self-priming.

Shop our RV water pump range or call 09 820 8023.