Yamaha EX: Engine Stalls at Idle or Hunts

The EX stalls when riding slowly or docking, or the speed hunts. That often has to do with throttle body, false air or voltage. M-JET DIAGNOSTIC gives you the numbers.

What you do

• Check the fault memory for throttle valve, air and voltage messages
• Idle live values: engine speed, throttle angle, intake pressure, voltage
• Activate cylinders 1 to 3 individually
• After cleaning, teach idle and throttle valve

Order

First look for simple causes: battery, connectors, hoses. If the memory shows nothing, watch intake pressure at idle. It should stay steady. If it flutters, false air is suspect. If the throttle body was cleaned, learning is the last step. For all tests the engine may only run with a water supply. If neither memory nor live values show anything conspicuous and the engine still stalls, the cause lies outside what a diagnostic tool sees, such as fuel supply, compression or mechanics. After an oil change also check the oil level: overfilling costs RPM on the TR-1 engines.

Related topics

• Yamaha EX, EX Sport, Deluxe and Limited: What the App Shows per Variant
• Buying a Used Yamaha EX: Diagnostic Check Before You Buy
• Yamaha WaveRunner Rough Idle: Diagnostics
• Diagnostics and fault codes for your Yamaha model
• All Yamaha WaveRunner diagnostics topics

Everything runs via app over Bluetooth, for Yamaha WaveRunners from model year 2002 to today. Learn more about the M-JET DIAGNOSTIC for Yamaha WaveRunner.