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Waverunner EX 2020 stalls after 15 seconds at idle every time

bigwavebw

Member
Messages
1
Reaction score
0
Points
10
Boat Make
Yamaha
Year
2020
Boat Model
Other
Boat Length
14
Raw water coolant line on bottom rear of motor came loose and filled hull 1/3 or more full of salt water.
Hull was drained but left on floating dock for a few months before it was delivered to me.
Desalted everything, popped inspected and salt treated every connection.
Oil was milky and engine was purged, pickled, flushed, 2 oil changes completed, no signs of water in oil found since.
Starter motor and cables / battery (terminals are new clean and tight )/ starter solenoid / replaced due to corrosion from flooding
Start stop handle bar module replaced due to intermittent start button failure, previous issue before flood / idle stall problem
Idle stall problem is new and post flooding of machine

Ski starts and performs under power normally when throttle is being used.
Let go of throttle it drops into a smooth idle for 15 to 20 seconds and then engine dies abruptly, EVERY TIME, no stumble, no rough idle or loss of rpm before stall, turns off as if you pulled lanyard or hit kill button.

CanDoo Pro shows no codes, monitored on/off switches remaining in operational positions.
Live monitoring data all within parameters,
TPS voltage and throttle body angle % holding steady at idle and increase - decrease with throttle input smoothly, the mechanical movements of throttle blade seem to match input and move smoothly as expected.
Live data shows 13.5+ volts charge when running, new plugs, fuel injectors sonic cleaned baskets changed flow bench tested and functioning 100%.
Coil packs ohm out good, all three cylinders are firing properly, compression +- 7% across all 3,
Fuel rail remains fully pressurized after stall.
8 out of 10 restarts it fires up like normal on occasion it takes maybe 20 to 30 seconds on starter to start.
Fuel tank pumped empty fresh non ethanol in machine, lines and fuel rail purged of old fuel.

Problem presents like a shorted IAC (idle air control) solenoid, but this ski does not have one that i can find on machine or in drawings / parts list

There is a set screw with lock nut on the throttle body, is this the mechanical idle speed adjustment?
Is there an internal IAC device in throttle body or a separate air intake journal for idle air that could be partially salt fowled?

The time interval from throttle release to idle rpm reached to stall out is very consistent, 10 to 15 seconds.
The actual stall event is immediate, no rpm decline, no stumble, no symptoms of fuel starvation.

I am stumped......
 
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