2013 fisherman with Yamaha F350 shut off on idle

[JPE]

2012 Yamaha †350 shuts off on idle. I replaced the fuel water separator, and the filter, didn't find any water. Engine does not shut off when it's running only in idle. Any ideas of what I should check next? Thanks

 

[seasick]

I would check the fuel pressure check the fuel pressure

 

[DennisG01]

Also, try taking the fuel fill cap off - see if that makes a difference.

 

[seasick]

Also, try taking the fuel fill cap off - see if that makes a difference.

OP states that motor runs fine at speed. That would eliminate a tank vent issue as well as clogged fuel filters.
I suggested a fuel pressure test since it may be that a pump is weak but my gut tells me the issue may not be that simple.

 

[SkunkBoat]

Could be some kind of Idle Air problem. Not familiar with the Yamaha..dunno if it has an IAC valve

 

[seasick]

It's a 350, could be anything

 

[DennisG01]

OP states that motor runs fine at speed. That would eliminate a tank vent issue as well as clogged fuel filters.
I suggested a fuel pressure test since it may be that a pump is weak but my gut tells me the issue may not be that simple.

I thought of that, too. I'm thinking that it's "possible" that the low RPM doesn't create enough suction via the low pressure pumps to overcome a small blockage... but the increased RPM does. 'Course, I'm assuming this engine has the block-mounted LP pumps and not an electric pump?

It's one of those... "it's easy enough to rule out things".

 

[Sardinia306Bimini]

Could be some kind of Idle Air problem. Not familiar with the Yamaha..dunno if it has an IAC valve

I thought the same thing as effect is similar.
AFAIK the F350 has no IAC Valve, same electronic throttle valve as Suzuki DF300 has.
Some smaller Yamahas have IAC valves, what I was not aware of, probably because they work as supposed and not have to be replaced at least once a year like Suzuki ones.
I really loved my Suzukis and If I should repower then it would be most likely a Suzuki, but I find it just incredible that Suzuki was not able to fix the IAC problem in many years.

Chris

 

[SkunkBoat]

I thought the same thing as effect is similar.
AFAIK the F350 has no IAC Valve, same electronic throttle valve as Suzuki DF300 has.
Some smaller Yamahas have IAC valves, what I was not aware of, probably because they work as supposed and not have to be replaced at least once a year like Suzuki ones.
I really loved my Suzukis and If I should repower then it would be most likely a Suzuki, but I find it just incredible that Suzuki was not able to fix the IAC problem in many years.

Chris

only replaced one IACV in 12 years on my DF140. Carb spray usually got it good for another year. Thats a symptom though. stalling out in idle or especially, stalling out when you quickly throttle back to idle.
Throttle closes and it doesn't get enough air. The IAC was contolling the bypass air.
New zukes and yammies don't have a separate IAC but the throttle body has to be doing the same thing internally.

 

[DennisG01]

Although my experience with IAC's comes from a different brand, a bad IAC also would show as an inability to even start. Basically, anything at idle.

The OP didn't say anything about starting problems - to me, it came across as "it will start fine... but eventually die off".

I guess it would be helpful to hear a better explanation.

 

[Sardinia306Bimini]

I changed about twice in 6 months season the IAC Valve on my 2011 DF200 V6 on the dive boat, cleaning with brake cleaner helped for a week or so, then problems started again. The good thing is that changing the IAC Valve is a easy 5 Minute task and
instead of 200$ original Suzuki IAC Valves I - as many others- just buy a couple of 30$ IAC valves in Amazon and call it a day. They are same and last same.

The most obvious thing happen with a failing IAC valve on a Suzuki is that the engine will not cold start, even not in hot Costa Rica. Only way to start is put control in throttle mode and accelerate, fire engine up and leave it to warm up the engine.

However, F350 don't have IAC valve so thats not the problem,
not keeping idle rpm is either a problem of fuel mix or misaligned cables/software if digital control.
wrong fuel mix can be the fuel pump, fuel restriction, some sensor malfunctioning

@JPE
starting is not a problem, not cold and not hot?
Will the engine fire immediately up after she stopped while idle
Will wiggle the control help
Do you have push-pull cables or a digital control?


Chris

 

[SkunkBoat]

I changed about twice in 6 months season the IAC Valve on my 2011 DF200 V6 on the dive boat, cleaning with brake cleaner helped for a week or so, then problems started again. The good thing is that changing the IAC Valve is a easy 5 Minute task and
instead of 200$ original Suzuki IAC Valves I - as many others- just buy a couple of 30$ IAC valves in Amazon and call it a day. They are same and last same.

The most obvious thing happen with a failing IAC valve on a Suzuki is that the engine will not cold start, even not in hot Costa Rica. Only way to start is put control in throttle mode and accelerate, fire engine up and leave it to warm up the engine.

However, F350 don't have IAC valve so thats not the problem,
not keeping idle rpm is either a problem of fuel mix or misaligned cables/software if digital control.
wrong fuel mix can be the fuel pump, fuel restriction, some sensor malfunctioning

@JPE
starting is not a problem, not cold and not hot?
Will the engine fire immediately up after she stopped while idle
Will wiggle the control help
Do you have push-pull cables or a digital control?


Chris

My problem with IAC was mostly when backing off to idle from speed. Thats how it would begin. Then progress to stalling at idle. It never was a problem starting. I think I remember there was a bypass adjustment for setting the idle.

Back to the OP problem. I just wanted to put it out there that it could be (lack of) air, and not fuel, causing that symptom. Maybe pressure sensor..