How to troubleshoot Xylem’s Rule LoPro bilge pump: Priming & motor cartridge tips
Xylem’s Rule LoPro bilge pump is the most low-profile pump in the Rule product line, standing just 2.4 inches (6 cm) high it’s engineered for vessels with tight bilge spaces. While the LoPro is designed for reliable, automatic operation, a small number of users encounter slow priming or need to reconfigure the motor cartridge's water-sensing height. This page walks through both issues step by step, with a full video and written troubleshooting guide from the Rule technical team.
Troubleshooting guide
Problem 1: The Rule LoPro bilge pump is slow to prime
Cause: A clogged vent hole in the discharge port is the most common reason the Rule LoPro bilge pump has difficulty priming. This small vent hole allows air to escape so water can enter the pump cavity. When it becomes blocked, the pump struggles to draw water in efficiently.
Solution:
- Locate the vent hole on the discharge port fitting.
- Straighten a standard paper clip.
- Insert the paper clip into the vent hole and clear any debris or buildup.
- Reattach the discharge fitting securely.
- Reconnect power and test the pump.
If priming is still slow after clearing the vent hole, the motor cartridge water-sensing height may also need adjustment (see Problem 2 below).
Problem 2: Adjusting the motor cartridge water-sensing height
The Rule LoPro ships from the factory with the motor cartridge in the low position, which activates the pump when water reaches approximately 1.3 inches (3.25 cm). In some installations, particularly those where the pump cavity is small, the pump may turn on before the cavity has enough water to prime efficiently.
Solution: Flip the motor cartridge to the high position.
- Disconnect power to the pump before handling any components.
- Rotate the motor cartridge to unlock it and pull it free.
- Flip the cartridge upside down so the "H" mark faces upward.
- Reinsert and rotate the cartridge to lock it in place.
- In this orientation, the pump activates when water reaches approximately 2 inches (5 cm), giving the cavity more time to fill before the pump engages.
When to use low vs. high position: Use the low (factory default) position for most installations. Switch to the high position if you observe slow priming that is not resolved by clearing the vent hole, or if your bilge has a larger cavity that benefits from a higher activation threshold.
Safety information
Always disconnect power before servicing your bilge pump. When the motor cartridge is removed, the impeller is exposed. Never handle the pump with power connected.
Additional fitting guidance
- Rule offers both straight and 90° angle discharge fittings.
- A check valve (inline non-return valve) is available and compatible with the straight fitting.
- Do not use the check valve with the 90° fitting. Combining these two components creates excessive back pressure, which can reduce pump performance.
Frequently Asked Questions
The most likely cause is a clogged vent hole in the discharge port. Use a paper clip to clear the hole, reattach the fitting, and test again. If the issue persists, try flipping the motor cartridge to the high-sensing position so the pump waits until there is more water in the cavity before activating.
Remove the motor cartridge by rotating and pulling it free (with power disconnected), then flip it upside down so the "H" mark faces up. This raises the activation threshold from 1.3 inches to 2 inches (3.25 cm to 5 cm). To return to the factory default low-sensing mode, simply flip the cartridge back to its original orientation.
Yes, but only with the straight discharge fitting. Do not use a check valve (inline non-return valve) with the 90° angle fitting, as the combination creates excessive back pressure that reduces pump performance.
The LoPro ships in the low water-sensing position, which activates the pump when water reaches approximately 1.3 inches (3.25 cm).
Yes, provided you disconnect power to the pump first. When the cartridge is removed, the impeller is exposed. Never handle the pump while it is connected to power.
Xylem offers both straight and 90° angle discharge fittings. A check valve / inline non-return valve is also available and compatible with the straight fitting only.