Jet Ski and Jet Boat Pump Care: Clearing the Intake Grate and Checking the Impeller and Wear Ring

Some newer Sea-Doo models have the iDF (Intelligent Debris Free) system: stop, press the iDF button and follow the display; it reverses the pump to push debris out. Other models may have their own procedure in the manual. If that does not fix it, or you do not have such a system, go to the next step.

Stop the engine and remove the lanyard or key fob. If you are on the water, get to shallow water you can stand in (calm, away from traffic) or tow the craft in. The best place to work is on the trailer, on level ground, with the craft secured and the engine cooled.

With the flashlight, look up into the grate from underneath the hull. Pull out weeds, plastic, leaves and rope with a blunt hook or stick, working from the outside. Do not stick your fingers between the grate bars toward the impeller. Cut rope or fishing line carefully with a knife and pull out the pieces.

Rope and fishing line often wrap around the driveshaft just in front of the impeller, where it is hard to see. Shine the light through the grate at an angle. Tight wraps can damage the shaft seal and let water into the hull. If a rope is wrapped tight and you cannot remove it easily, the grate or pump may need to come off (step 9).

From the back of the craft, shine the light into the nozzle (and through the steering nozzle and reverse bucket) toward the impeller. Pull out anything lodged there. Check that the steering nozzle and reverse gate move freely when someone turns the handlebars and works the reverse lever, with the engine off and the lanyard removed.

Through the grate or nozzle, look at the leading edges of the impeller blades (photograph them with the phone for a closer look). Look for:

• Nicks, chips or dents: from rocks or sand. Small dings can cause vibration and cavitation.
• Rolled or bent edges: usually from sucking up rocks or running in shallow water.
• Cracks or missing pieces: stop riding; this needs a dealer.

Look at the gap between the impeller blade tips and the wear ring around them. It should be a very small, even gap. Warning signs are deep scratches or gouges in the ring, a ring that looks oval or worn more on one side, or a gap that looks noticeably larger than before. The exact allowed clearance is in your service manual and is measured with feeler gauges, usually with the pump removed. If the craft revs high, goes slow, and the grate is clear, a worn wear ring is the usual cause.

Sea-Doo describes its standard composite wear ring as a sacrificial part: when a stone or stick gets past the grate, the ring is meant to take the damage so the more expensive impeller and driveshaft don't. That is why a chewed-up ring is common and not a disaster, and why Sea-Doo lists wear rings among normal wear items (like filters) rather than warranty parts. For riders who beach often or run in shallow, gritty water, Sea-Doo also sells a tougher stainless wear ring for many models; ask your dealer if it suits your use.

Look at the pump housing, nozzle and ride plate for cracks or damage. Sea-Doo says to contact a dealer before your next ride if you see cracks or damage. Many pumps have an anode (sacrificial metal) that protects them from corrosion; replace it when it is heavily worn, as your manual describes.

On many models the intake grate is bolted on and can be removed with hand tools to clear stubborn debris; check your manual and use the correct tools. Removing the pump to replace the impeller or wear ring usually needs special tools to hold the shaft and remove the impeller, plus sealant and torque specs from the service manual. Most owners have a dealer or jet-pump shop do this.

After any ride in saltwater, dirty or sandy water, rinse the pump inside and out with fresh water. Flush the cooling system the way your manual describes. For example, Yamaha's routine connects a garden hose to the flush fitting and runs the engine at idle for a few minutes, while Sea-Doo models with closed-loop cooling only need the exhaust flushed. Do it exactly as your model's manual says; the order of turning on water and engine matters. If your craft has a flush connector or a flush hose inside the hull, put its cap back on afterward. Owners report that a flush fitting left uncapped sprays cooling water around the engine compartment while riding and can lead to overheating.

Once the craft is back in the water, start it and check that the pilot water stream (the small cooling water outlet) is flowing. On a test ride, note top speed and RPM if your gauge shows them. Record them in BoatMend. A slow rise in RPM with a drop in speed over time points to wear ring or impeller wear.

• Avoid shallow water. Yamaha suggests stopping the engine when the water is about 3 feet deep when coming to shore, and pushing back out to at least that depth before restarting, so sand and pebbles are not sucked in.
• Idle slowly (or turn off and push) through weed beds, and avoid running over lines, ropes and floating trash.
• Never ride up onto a beach or ramp under power.
• Check the grate before every ride, as part of your pre-ride routine.