The engine stops when a Yamaha PWC rolls over, and that is intended. The trouble starts when the ski is back upright and still refuses to start, or when the engine cuts out with the hull level. The part behind both is the slant switch, which every model the app supports has. On the stand-up SuperJet of 2021 and later it shuts the engine off on a capsize, which makes that ski the one where owners meet the switch first.
Code 47, code 71 and which ski uses which
The code number depends on the control unit generation. Generation B, meaning the VX1100 from 2005 and everything newer, including SuperJet, JetBlaster, EX, the three-cylinder VX, the 1.8-litre and the 1.9-litre models, reports the slant switch as code 47. Generation A, which covers the FX140, FX1000, FX1000(A), FX1100 and the GP1300R, reports it as 71. Lists on forums sometimes mix the two, so read the description rather than the number.
The M-JET Diagnostic supports all of these, SuperJet included, so the code and the live switch value are available on any model in its list.
Ski upright, engine won't start: look at the live value
Put the ski level, connect the app and open the live data. The slant switch status is among the switch values, depending on the model. With the ski sitting normally it should report its upright state. What you see splits the problem quickly.
- The switch still reports tilted on a level ski. The switch or its connector is the suspect, and a stored 47 or 71 backs that up.
- The switch reports upright. Then it isn't what holds the engine off, and the lanyard, the handlebar stop switch, battery voltage and the relays come next.
- The value flickers when you move the harness. That is a contact problem, usually in the connector rather than in the switch body.
Water in the plug
After a capsize water gets into places that normally stay dry, and plug connectors are where it does its quiet damage. A connector that was wet and then dried can leave a film on the contacts that interrupts the signal now and then. Unplugging it, cleaning the contacts and seating it firmly again costs nothing and is worth doing before you order a switch. While you are there, look at the battery terminals, because a loosened terminal looks like a dead ski too.
Engine cuts out with the hull level
If the engine drops out while you ride upright, say in chop or in a hard turn, the slant switch signal is one candidate. The handlebar stop switch and a poor battery connection are others. A recorded test ride separates them. Log the switch values and battery voltage together and see which one moves at the moment of the cutout. If nothing in the log changes and the engine simply stops, that is a finding as well: the fault probably isn't in the switch circuit.
What the scan can't tell you after a flip
A diagnostic readout can't know whether water entered the cylinders or the intake during the roll, and it can't measure compression loss. That is a mechanical question. Don't crank the engine again and again on a ski that spent time upside down; look at it first. The scan covers the electrical side only: the switch, its code, the connector and the voltage.
The model-specific details are on the page for SuperJet diagnostics. The order that makes sense is level ski first, switch value second, connectors third, and a replacement switch last.
