How to Troubleshoot a Boat Macerator

by Robert Osborne
Macerator failure is not fun.

Macerator failure is not fun.

A boat's macerator pump is used in the boat's sewage storage and handling system. A macerator grinds and chops up the sewage, which allows it to be pumped to or from holding tanks. A pleasant outing on the water can be ruined when a macerator pump decides to stop working. When this happens, sewage can back up in the system and potentially overflow in the toilet compartment. Proper troubleshooting can solve the problem.

Check the simple stuff first. Before you start ripping apart your boat's sewage plumbing system, rule out some simple causes of the problem. Check your fuse or circuit breaker that feeds power to the macerator. If the circuit breaker has tripped, reset it. If the fuse has blown, replace it. If the macerator still doesn't work, use a volt meter to ensure that there is power at the macerator. You should read 12 volts DC for a 12 volt system and 24 volts DC for a 24 volt system. If you don't have power at the macerator and the circuit breaker or fuse seems functional, then the problem is between the two system components. Is there a switch or relay between the circuit breaker and macerator? See if each component is getting power. Look for broken or corroded wires or connections. Replace or repair the needed part.

Listen to the macerator. Assuming you have power at the macerator, see if it's making noise. If not, there may be an obstruction in the impeller. Most macerators have a spot on the end of the motor where you can spin the motor's shaft. With the power off, see if the shaft will spin. If the shaft doesn't turn, there may be a blockage at the impeller. If the shaft spins freely, the motor is bad. If the macerator is making a high-pitched noise and sounds like it is running fast, then it may be running dry. Are you trying to pump from an empty tank? Have you opened the valves that allow sewage to reach the pump? Perhaps there is a blockage in the hose leading to the pump. If the macerator sounds like it is running slow and makes a grinding noise, there might be an obstruction at the impeller. The sound also might result from a blocked output hose or from a closed valve on the hose.

Fix the problem. You've done all that you can do without removing the macerator. Turn power off to the macerator, and make sure the valves to the macerator are closed. Carefully remove the macerator pump. Look for obstructions inside the macerator intake. Hair, peach pits and other foreign objects can slow down the pump or can keep it from pumping altogether. Remove all obstructions. Apply power to the macerator, and see if it works. If the macerator appears to operate normally, reinstall it. If it doesn't, it is time for a new macerator. Many boaters carry a spare macerator in their vessel's parts locker, so that the macerator can be swapped out with minimum down time.

Items you will need

  • Volt Meter
  • Spare Fuses
  • Screwdriver

About the Author

Robert Osborne has written professionally since 2010. He writes for eHow, specializing in aircraft and boat maintenance, home renovation and electrical engineering. Osborne earned his Bachelor of Science in electrical engineering from George Washington University.

Photo Credits

  • Fun Boat Trip 2 image by Viktor Gmyria from Fotolia.com