The VX Cruiser has been sold with two engines: the 1052 cc four-cylinder MR-1 (VX1100, 2005 to 2015) and the 1049 cc three-cylinder TR-1 (VX, from 2015/16). Both generations show up in forum threads about overheating beeps and a ski that slows itself down. The thread usually ends in a replaced sensor, and the cause often turns out to be water that is not flowing the way it should.
The pisser test comes first
Owners call the small tell-tale tube at the front the pisser. A commonly used check is to watch it while the ski runs in the water: water leaves at the rear, but nothing comes out of the pisser. That means the route is closed somewhere in between. It is a crude test, and it takes a couple of minutes. That is why it belongs before anything electronic.
What closes the path? In forums the list is fairly consistent across EX, VX, FX SVHO and FZR boats: a pump that cavitates, debris sitting in the intake grate, an impeller with chipped blades, a plugged small cooling-water passage, or exhaust manifold passages that clogged after poor flushing. The sensor is usually the least likely item.
What the live data adds
A diagnostic app will not find any of those blockages. It shows you how the engine reacts to them. Connect the M-JET Diagnostic, ride the same route that produced the beep and record the run with the data logger. Put rpm and engine temperature side by side, and on the three-cylinder VX add the exhaust manifold water temperature. The codes on that generation are 15 for the engine temperature sensor and 65 for the manifold water temperature, though numbers can differ between control unit generations and sources.
- If the temperature climbs only when you hold higher rpm and settles when you back off, flow is not keeping up with the load. That fits a partly blocked path or a pump that starts to cavitate under load.
- If the climb starts early and runs in a steady line whatever the rpm, suspect the manifold and the cooling passages. Deposits build slowly and show up as an engine that can no longer shed its heat at any speed.
- If one value jumps while the other stays calm, the jumpy one is probably the faulty reading, so go to its connector.
These readings give a direction, not a verdict. Cavitation, impeller wear and a plugged manifold are mechanical, so they stay outside what the scan can prove.
Long rides and calm water
EX owners describe beeps on long tours that rarely happen on short runs. The same time-dependent pattern is worth logging on a VX. If the alarm only arrives after thirty minutes, the log shows whether the temperature crept up slowly or stepped up suddenly, and those are different problems.
If the manifold is the suspect
A manifold clogged after poor flushing has to be cleaned or replaced, and that job belongs in the service manual, not in the app. What the app can do afterwards is confirm that the engine temperature stays in its normal band during a full test ride, which is the proof that the repair worked.
The warning tone and the rpm reduction can come from the temperature warning or from other causes. Check battery voltage and the switch states in the same log before settling on a diagnosis. There are separate pages on overheating and the temperature sensor and on overheating on the three-cylinder VX.
