2008 Sugar Sand Oasis stalling at idle speeds

[Tremor]

08' Sugar Sand Oasis runs fine for a while then i go down to very low speeds or idle and it stalls. It starts back up eventually if i wait about 30 minutes or so. But it doesn't start if i try right away or only wait 10-15 minutes. So frustrating.
Always runs great at higher speeds.
Any help is greatly appreciated.
Engine is the Mercury 250
Thanks

 

[Gym]

08' Sugar Sand Oasis runs fine for a while then i go down to very low speeds or idle and it stalls. It starts back up eventually if i wait about 30 minutes or so. But it doesn't start if i try right away or only wait 10-15 minutes. So frustrating.
Always runs great at higher speeds.
Any help is greatly appreciated.
Engine is the Mercury 250
Thanks

I don't have your type boat but it sounds like carburation to me. Is this an open carburetor fuel injected? I would. probably start with checking/removing air cleaner. If still problematic try running a can of Sea Foam through the system to clean out the fuel delivery system. Does it run smooth at speed? Do you think it's getting heat soaked? Have you tried opening the engine compartment hatch at idle incase you have an exhaust leak killing your engine?

 

[Tremor]

I don't have your type boat but it sounds like carburation to me. Is this an open carburetor fuel injected? I would. probably start with checking/removing air cleaner. If still problematic try running a can of Sea Foam through the system to clean out the fuel delivery system. Does it run smooth at speed? Do you think it's getting heat soaked? Have you tried opening the engine compartment hatch at idle incase you have an exhaust leak killing your engine?

 

[Tremor]

It's fuel injected. I'll check the air cleaner and he Some sea foam cleaner.
It does run very smooth at all speeds above 7-9 mph.
What exactly does heat soaked mean?
Tomorrow morning I'll try to run it with the engine compartment open.
Thanks so much

 

[Gym]

Heat soaked doesn't necessarily mean the engine throws an overheat or high temp light. It refers to the engine bay's heat situation in general & how the engine absorbs and dissipates heat, how well the coolant system works, how well the oil stays slippery, and of course how much power the engine makes. Often it makes restarting an engine difficult until it cools down. Think of it as heat exhaustion for a human. We would just need to rest and drink water to recover.

If your engine is getting heat soaked trying it (safely) with an open engine compartment or the blower on may help you diagnose the issue.

What is the location & altitude of your boating location? How hot has it been during these stalling Incidents?

I'm hoping a can of Sea Foam in a full tank of gas will clean out your fuel delivery system. It could still be a bad fuel injector or old/bad spark plugs. Let's try the easy/cheap things first.

 

[Tremor]

It has been 85-90 degrees and humid. Now that you mention the temperature, the times i went out before when it was only 70-75 degrees outside, the incident didn't occur.
I'll try the Sea Foam cleaner.
I've heard people talk highly of the Lucas fuel cleaner, is that the same as the sea foam. Or is the sea foam marine specific?

 

[Bilmon]

this engine is a direct injected 2-stroke[ Optimax]. It doesn't really have a air cleaner, just more of a shroud. Not familiar with the Opti, I have a EFI 240 but they seem to share a lot outside the injection system. Some 240's have trouble hot restarts [my son's for one does it at random] One thing I know can affect it are the temp sensors. The ECU uses the temp to set the fuel injection if the port head sensor gets bad it defaults to a cold reading so the ECU will set the injectors rich, kind of like choking a hot engine. Don't know if that could be the issue, just a thought

 

[Gym]

Based on what @Bilmon mentioned about temp sensors have you smelled fuel at idle or seen any signs of it in the water? Also wondering what your location and altitude above sea level you're operating at.

On the hot days you mentioned (85-90) try leaving the blower on at lower speeds. That may help dissipate the heat. Density altitude at those temps could play a big role so let me know what altitude you're operating at.

 

[Tremor]

Pretty low. On the foot of lake Erie near niagara falls.
Looks like about 100 meters high

 

[Gym]

Pretty low. On the foot of lake Erie near niagara falls.
Looks like about 100 meters high

Ok so altitude is not an issue. When were the spark plugs changed last? I don't believe they are causing this issue but they could be a contributing factor.

 

[Tremor]

Baught it two months ago from private owner so not sure when the plugs were changed. I can have them looked at.

 

[Bilmon]

Agree with @Gym on plugs I know the 240's can be hell on plugs and are only happy with the spec plugs. Manuel for your motor calls for NGK PZFR5F-11

 

[Tremor]

Agree with @Gym on plugs I know the 240's can be hell on plugs and are only happy with the spec plugs. Manuel for your motor calls for NGK PZFR5F-11

Agree with @Gym on plugs I know the 240's can be hell on plugs and are only happy with the spec plugs. Manuel for your motor calls for NGK PZFR5F-11

 

[Tremor]

Thanks again. I'll check the plugs tomorrow.

 

[Tremor]

So i put a can of Seafoam in it on Saturday and ran for a couple hours with no issues. I even went down to low speeds again.
And then again today i put in another can if Seafoam and ran for a couple hours. Today i basically tried to stall it out, running a idle and low speeds the entire time. I didn't run the blower or open the engine compartment at all either because i was trying to replicate when it has stalled prior. Never stalled. In fact, it seems to be running better in general, especially at the lower speeds and idle. Is it possible the the seafoam cured the issue?

 

[Gym]

So i put a can of Seafoam in it on Saturday and ran for a couple hours with no issues. I even went down to low speeds again.
And then again today i put in another can if Seafoam and ran for a couple hours. Today i basically tried to stall it out, running a idle and low speeds the entire time. I didn't run the blower or open the engine compartment at all either because i was trying to replicate when it has stalled prior. Never stalled. In fact, it seems to be running better in general, especially at the lower speeds and idle. Is it possible the the seafoam cured the issue?

Ok good. So your boat got two cans of Sea Foam. Now you need two cans of beer to celebrate. Sounds like the Seafoam cleaned the injectors. Glad it worked out.

 

[Tremor]

So now, another issue. Not sure if they are related or not.
It's ok at lower speeds and then i get on it a little and the Rpms rev high but the boat doesn't pick up speed. Engine is working hard but im just not gaining speed.
Happening Sporadically, but seems maybe it's happening after cruising at lower speeds for a while.
If i wait a little or shut it down for a bit it seems to correct itself.
Thanks for any input.

 

[Gym]

not very familiar with the Sugar Sand Oasis @Tremor. Is there a direct connection between the motor and impeller as in our Yamahas? I would get my hands on the impeller to make sure there is no play as if the splined shaft, I believe it rides on, is stripped.

 

[Bilmon]

Sure sounds like there is something in the pump, doesn't take much, a tiny piece of wood or anything is all it takes. It is direct drive to motor but the pumps are really beefy, unlikely to strip but then it's a boat and anything is possible

 

[Bilmon]

Also if you have the Hydro Surge spring loaded grate I'd get rid of that damn thing and replace it with a fixed grate, there is a 6 tine aluminum and a 11 tine stainless available. I run the stainless, nothing gets past that thing as apposed to the Hydro Surge that dumps every thing though. It will clog with weeds easy though if your in a weedy area. The Hydro Surge are also known to lose tines and that can be a disaster