340hp Marinepower will stall when cold

[BrentP]

Specifically, when you put it into gear. Basically the motor bogs down then throws a solid beep. If you throw it back in neutral before it shuts off, it’ll rev a bit and stay running clean. I can usually massage it into gear without it shutting off, and it only happens when it’s Texas cold (usually in the low 60s and water temps in the low 50s). In the summer and after the boat gets to even a mild temp (80 degree engine temp) it’s fine.

It’s not a big deal as you can just idle the boat for 5 minutes and it’s fine. The motor is fuel injected so it shouldn’t be any different “cold” or “warm”. And it happens when it’s in gear - so when stress is on the motor.

Ideas? Fuel pump getting old? VDrive or Transmission are hard to turn cold?


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[lee]

When was the last tune up? IAC valve changed? TPS?

[BrentP]

I had a full annual done on it last year. Honestly, the dealer here in Austin is new to tige and seemed a little lost on the marine power motor. But it has the Ecm scanned, no codes or issues, new plugs put in it, etc. the boat was acting the same way before and after

No modules were changed.


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[KoolAid]

I'm with Lee on the IAC. Especially with no codes being thrown.

[BrentP]

Cool, I appreciate it. It’s super hard to diagnose - we went out after the freeze and let it warm up to about 120 or so and had no issues. MAybe a proactive replace of the iac is in order...


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[freeheel4life]

I'm late to this one and Lee and Kool are on it. Only thing I would add is off the IAC sounds like it's sucking a lot of air with TB closed at idle you could have a fuel issue...but this usually comes with a backfire in the intake after everything warms up/has hot IATs

[BrentP]

Yah no back fires. Also the boat idles fine In neutral just not in gear. I’d think of it was fuel we would see other issues?

That being said, I’ve also had a very periodic issues where when the boat is luke warm and we idle out of a long no wake cove it’ll act like it’s starved for gas. Kind of similar symptom as this. But I suppose that could be the IAC as well starving it of air...


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[Majr808]

Where is the IAC valve located on this engine? I have my throttle body off of the engine but can't find the IAC.

[BrentP]

Where is the IAC valve located on this engine? I have my throttle body off of the engine but can't find the IAC.

It should be on the throttle body side. Part number 25 in this shitty picture from the marine power parts manual




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