2002 Seadoo Utopia 185 240 EFI - Water getting in from Engine

[sailsail]

Fellow Jet Boaters,

I’m looking for insights on a concerning water intrusion issue I encountered today with my jet boat, which I’ve owned and maintained for 10 years. It has never taken on significant water—typically just a few cups from the drain plugs.

Incident SummaryWhile anchored for about an hour, I noticed the bilge was full. The drain plugs were secure, and no water entered during that time. I ran the bilge pump (which revealed a failed float switch I’ll replace) and redistributed weight to check for hull breaches; none were evident, and the waterline remained normal.

After cruising for ~30 minutes, I returned to the dock. The bilge pump ran for ~30 seconds on residual water, then stopped. The boat sat normally at the waterline. I left for ~20 minutes to retrieve the truck and trailer. Upon return, the waterline was still normal, and running the bilge pump produced no discharge from the through-hull.

During the short idle to the ramp and loading (5–10 minutes total), the boat behaved normally. However, in the parking lot, removing the drain plugs released an unprecedented volume of water—draining continuously for ~7 minutes.

Home Troubleshooting

1. Reinstalled plugs, jacked the trailer, and supported the hull on pads.
2. Filled the bilge with ~6 inches of water (just above the jet pump housing but below the engine). Let it sit for 20 minutes—no leaks observed. Drained without issue.
3. Inspected all through-hulls, cables, and mounting hardware—no structural defects or anomalies.
4. Ran the flush hose for 20 minutes—no bilge accumulation.
5. Did not start the engine (to avoid noise near my sleeping toddler).

In hindsight, I should have relaunched the boat on the trailer, secured it, and run the engine under load to replicate the ingress. That opportunity was missed.

Questions

• Where is water most likely entering under power?
• Common failure points in jet boats (e.g., drive shaft seal, cooling system, impeller housing, hull fittings)?
• Has anyone encountered delayed/surge ingress that only appears during operation?

Any diagnostic tips or similar experiences would be greatly appreciated.

Thank you in advance.

 

[sailsail]

I have searched this forum with Grok for similar and this is all I can find. None of these match the engine or model of boat.
I do want to check the mufflers and the hoses. Any idea of an easy way to fully pressurize these on the trailer? I do not believe the hose provides enough water. From my basic troubleshooting the hose water goes into the same intake as the little scoop in the tunnel and most of it drains out the tunnel. What little water makes it to the engine is barely enough to cool it and I don't believe it is going to fully fill the mufflers or exhaust system to the extent it gets in the water. I do plan to take it back to the lake just to dunk it and run in the trailer, however I would like to make sure I have a list of things to check.

1.​

• Problem: After ~10 miles at high speed, the bilge and ski compartment filled with hot water that drained for 5+ minutes after pulling plugs—far more than expected for a jet boat. No leaks seen stationary; owner new to jets and worried about cooling system failure.
• Common Causes Discussed: Faulty bilge pump (not auto-activating), worn carbon seal in jet pump, exhaust leaks heating the water, or hull seams/rub rail gaps opening under speed/load. Ski compartment drainage issues could also feed into bilge.
• Resolutions/Advice: Fixed bilge pump first; pressure-tested carbon seal by running on trailer in water (revealed leaks); inspected/replaced cooling hoses and exhaust clamps. Users recommend a GoPro for filming under power and a service manual for diagrams. One owner noted waves over bow contribute but not to this volume.
• Similarity to Yours: Matches the post-run surge and long drain time; hot water suggests internal source like yours (though you didn't specify temp).

2.​

• Problem: Bilge filled with ~20 gallons of warm water in just 5 minutes of cruising; shafts dry when inspected stationary. Happened consistently under way but not at idle or anchored.
• Common Causes Discussed: Pinhole exhaust leak (e.g., muffler can rubbing hull, creating hole); ruled out carbon seals initially but noted as secondary. Bilge pump overworked from prior use.
• Resolutions/Advice: Identified exhaust pinhole via running engine at 2-3K RPM on trailer (water sprayed from outlet); TIG-welded repair held on test run. Added auto bilge pump and advised against overnight docking due to seal drip. Sealant like 3M 5200 for temp fixes.
• Similarity to Yours: Exact match for ingress only during movement/trailering; your missed in-water engine test aligns with their hindsight advice.

3.​

• Problem: Bilge pumped hot water after minutes at anchor or in chop; dry when planing in calm water. Resealing drain plugs didn't help; ~1-2 gallons accumulated per outing.
• Common Causes Discussed: Exhaust can rubbing hull (drilled hole, leaking cooling water under throttle); poor factory bilge pump placement pooling water near engine. Lakeside cooling or manifold leaks.
• Resolutions/Advice: Observed water flow from engine hatch while running to spot exhaust rub; repositioned/upgraded bilge pump to low spot (Rule 900 GPH). Filled hull on trailer to test static leaks (none found). Emphasized running diagnostics at ramp with hatch open.
• Similarity to Yours: Delayed accumulation like your anchored hour, then post-cruise drain; your weight redistribution test echoes their static checks.

4.​

• Problem: Hour of use led to hot bilge water filling up, with auto pump failing; no spray visible out of water, but drained heavily post-run.
• Common Causes Discussed: Cracked carbon seal (audible spray on accel); turbo cooling pipe leak under pressure; steering cable seal; exhaust for heat source. Low engine placement worsens pooling.
• Resolutions/Advice: GoPro inspection while underway pinpointed seal; replaced carbon seal (remove jet pump/C-clip). Fixed cooling pipe clamp; one user sealed steering cable. Fresh fuel resolved related surges.
• Similarity to Yours: Post-trailering flood and no static leaks; your flush test (no water) rules out some cooling, but under-power seal test advised next.

From other forums:

1.​

• Problem: Bilge filled with ~5-7 gallons after 20+ minutes at speed; no water at idle/anchor, drained heavily post-run (similar to your 7-minute drain). Waterline normal until trailered.
• Common Causes Discussed: High-pressure cooling line clamp loosening under vibration/load, allowing hot exhaust/cooling water to seep in; ruled out hull cracks via static tests.
• Resolutions/Advice: Ran engine on flush hose with compartment open—spotted drip from line; tightened/replaced clamp ($20 part). Relaunch-on-trailer test confirmed fix; users suggest annual seal inspections for older jets.
• Similarity to Yours: Precise match for time-delayed ingress during cruise, your flush test (no leak) aligns but missed dynamic pressure; 10-year age factor noted.
• Link:2015 Yamaha SX240 taking on water - SOLVED

2.​

• Problem: After short outings, pulling plugs released "gallons" over 5+ minutes—far beyond normal cups; bilge dry at dock, no pump activation during use, but surge post-trailering.
• Common Causes Discussed: Loose livewell/aerator plumbing or transom fittings vibrating open under power; carbon seal weep amplifying if pump float fails (like yours).
• Resolutions/Advice: Pressurized hull on trailer (fill bilge, run engine)—leaked from aerator hose; resealed fittings with marine silicone. Added secondary pump; advice to check all thru-hulls with soapy water spray.
• Similarity to Yours: Identical post-use flood and normal waterline; your weight test and static fill mirror their diagnostics, but dynamic run advised next.
• Link:Drain Plug Releasing Alot of Water After Use

3.​

• Problem: Sudden bilge fill (~4-6 gallons) after 30 minutes cruising; hot water drained for minutes after docking/trailering, no ingress anchored or idling.
• Common Causes Discussed: "Pisser" tell-tale hose (cooling indicator) leaking back into bilge at higher RPMs; or jet pump carbon seal wearing, especially in older models.
• Resolutions/Advice: Headlamp inspection under running engine revealed pisser drip; rerouted hose and repacked seal. Users recommend GoPro filming thru-hull during op; fixed in one outing.
• Similarity to Yours: Matches cruise duration and residual pump run; your non-start at home echoes their noise-avoidance tip, hot water hinting engine source.
• Link:https://www.reddit.com/r/boating/comments/1cybt3f/yamaha_jet_boat_leak/

4.​

• Problem: Bilge flooded mid-trip (~10 gallons total, draining 8 minutes post-haul); no leaks static or at rest, but accumulated during 45-minute run in chop.
• Common Causes Discussed: Failed driveshaft carrier seal allowing shaft water ingress under thrust; common in jets after 8-12 years, worsened by prop wash.
• Resolutions/Advice: Trailer submersion with engine run pinpointed spray; replaced seal ($150 DIY). Emphasized bilge redundancy; one user added dripless upgrade.
• Similarity to Yours: Surge only under way/trailering, your inspection (no defects) aligns but seal needs pressure test; hindsight trailer-run advice spot-on.
• Link:https://www.thehulltruth.com/boatin...ney-well-spent-i-almost-learned-hard-way.html

5.​

• Problem: Engine bay flooded after hour run (~6-8 gallons, long drain on plugs); dry at anchor, normal waterline, but heavy post-trailer accumulation.
• Common Causes Discussed: Exhaust dump pipe or carbon seal failure dumping cooling water; ruled out ports via static fill.
• Resolutions/Advice: Hose-flush with RPM variation showed exhaust seep; resealed pipe. Forum consensus: Check rear compartment first for jets; added auto-pump upgrade.
• Similarity to Yours: Exact delayed flood and no static issues; your 10-year ownership matches wear patterns, flush test helpful but add RPM.
• Link:Scarab 195 HO impulse. Taking on water? Sinking? Why?