Engine stalls on throttle up

[Steve Moyer]

I just bought a used 2014 yamaha 242 limited s. Took it out (for the first time) the other day and when I put it in the water it fired up and we idled out no problem. When I hit the open water and throttled up , it ran a little rough, began to lose power, and stalled. It wouldn't restart immediately, almost like it was flooded, but after waiting a few minutes it restarted. I tried again, several times, thinking maybe it just needed to clean out. The result was the same. Seemed like it might be starving for gas. So I idled back in, and put it back on the trailer. When I got home I flushed the engines and it seemed to rev fine. Any ideas? Also just put two new batteries in.

 

[MIDLIFECRISIS]

Run some Seafoam fuel treatment through it, sounds like old gas. Also check your plug hatch switches, on mine I didnt have one of the handles turned all the way and would idle fine but not go over idle without feling like it was stalling.

 

[Steve Moyer]

That could be. I bought it used and it looked like it sat awhile. The batteries were also dead. It had a half a tank and I filled it the rest of the way before going out. Thanks for the reply.

 

[Julian]

@Steve Moyer A couple of additional thoughts....

1. Change the plugs...these engines are sensitive to old/fouled plugs
2. could it be starving for air? This is a long shot, but we had someone who put speakers in the air vent holes to the engine compartment and then the engines would idle fine, but when running high rpm would starve for air (again, a long shot...easy to check)

Keep on giving us updates...we'll figure it out for ya! Also, if you add your location to your profile, you might find that someone close has a YDS cable they can hook up to the engines and see if they are throwing a code.

 

[Bruce]

The cleanout tray has two switches that kill the engines when the it is opened. If the tray is not locked down or a switch is not correctly adjusted it can kill an engine when you throttle up. Vibration or hitting waves typically contributes. You can tape a nickel to the cleanout tray lid where it contacts the switch to test.

 

[Evildwarf]

Both motors stalling under load simultaneously?
My guess would be old/bad gas...seems like a coincidence to have an identical mechanical failure between both motors. I'm certainly not a mechanic but if both motors are stalling under load and they both pull from the same fuel source, seems like a likely cause. Could be electrical I suppose...but seems like fuel to me.
Could be clean out hatch but wouldn't the kill switches kill the motors completely, very different from stalling under load....
Yup, fuel.

 

[Steve Moyer]

Wow, what an awesome community of helpful boaters!!! Thanks for all the responses and informative knowledge. Ok, I got my seafoam, new plugs, nickles, and hatch info. Wish me luck. Not sure if I'll be able to drop it in the water today and test but at least I'll knock out a few possibilities. I'll be sure to update my results. Thanks again.

 

[Cobra Jet Steering LLC]

I also believe it is stale fuel causing the issue. We have a huge amount of humidity here and condensation in the fuel tank is very common.
I bet if you siphon some fuel from the bottom of the tank after the boat has been sitting for a day , place the fuel in a glass jug you will probably be able to see water settle on the bottom of the jug after it sits a while.

 

[Scuba_ref]

Also, if there is too much water in the fuel then an additive won't help. It will will cause phase separation and you will end up with a milky looking mixture at the low point of the fuel tank. That milky mixture doesn't burn at all. In that case you will need to pump that stuff out. The easiest way I found was to disconnect the fuel line going into the engine and then use my YDS software to activate the fuel pump until all I got was clear gas. You will have to do this for both fuel pumps and it might take a couple of times before you get it all out.

At worst you could siphon all the gas out and then wipe out the tank through one of the fuel pump holes.

I struggled with this issue this summer, so I got pretty good and pumping out bad fuel.

 

[ToddW850]

I agree with checking all of the suggestions above. You have a good boat here, so it will be something simple and we'll figure it out for sure.

 

[Steve Moyer]

Ok, so I finally took it out after new plugs, gas treatment, and clean out tray (nickle) fix. Unfortunately the same result. It does seem to be starving for fuel or air, because right after the restart out of frustration I floored it and it took off as normal but before it could even get up on plane it began to bog down and when I pulled back the throttles both engines stalled again. I can idle around all day with no problem. Seems to run fine. Another thing that was happening was the AUX Voltage alarm and warning kept coming on. It does have two brand new batteries and a pro sport 12 marine battery charger I keep it plug into. They were both fully charged. Oh and one more thing the gas gauge seemed to not be working right. I know there is almost a full tank and it popped up as a half a tank and I watched it deplete at a accelerated rate. There was no fuel trail in the water. I'll pull the hatch to tomorrow to confirm but, its too dark now.

 

[Murf'n'surf]

On the trailer or lift can you throttle up to see if you can zing up the rpm's briefly without a stall?

I'm still sticking with bad fuel. You need to pull the fuel sender and suck that fuel out off of the bottom. If you have a lot of water in the fuel, no amount of treatment will disburse it. Water in your gas will also cause irregular fuel gauge readings although it usually pegs it on full. Ethonal fuel can cause goofy gauge readings as well.

 

[SCSTWG]

On the trailer or lift can you throttle up to see if you can zing up the rpm's briefly without a stall?

I'm still sticking with bad fuel. You need to pull the fuel sender and suck that fuel out off of the bottom. If you have a lot of water in the fuel, no amount of treatment will disburse it. Water in your gas will also cause irregular fuel gauge readings although it usually pegs it on full. Ethonal fuel can cause goofy gauge readings as well.

I am with Murf at this point. In addition, running on the hose might put you in a better position to troubleshoot as well.

 

[Steve Moyer]

The odd part is, both times, when I got home, I flushed the engines, and on the trailer it doesn't seem to bog or choke out. I didn't run at high RPMs for too long because I didn't want to damage the engines. As long as I have hoses hooked up, how long/how high, could I rev it without a problem?

 

[Danielmailin]

Reving without a load does not require fuel, the ECM can tell by mass or pressure how much air is coming in thru intake and adjust fuel accordingly.

That is why the boat engine will behave differently in water under load then out of the water without load. I would not rule out fuel yet.
When diagnosing a car engine with a clogged fuel line, you can rev the engine to redline all day long in Neutral or Park, but if you take it on the road in 2 or 3 gear Wide Open Throttle, the engine will fall flat 2 to 3k RPM and and at times stall.
Just my 2 cents!

 

[Julian]

There is obviously something about the position of the pickups if this is a fuel issue.....no? My boat has a hatch to access the fuel tank, so looking inside the tank is much easier. I would think if it was getting a lot of water at idle, it wouldn't start at all. So it is either the position of the pickups that getting on plane puts move the water over the pick ups more, or the vibration is shaking the gas and mixing the water in more? Couldn't he try running the boat as much as he can to clear the water (figure out an RPM on the water where it runs rough but doesn't stall)? Or might too much water injected damage the engine?

 

[Murf'n'surf]

Reving without a load does not require fuel, the ECM can tell by mass or pressure how much air is coming in thru intake and adjust fuel accordingly.

That is why the boat engine will behave differently in water under load then out of the water without load. I would not rule out fuel yet.
When diagnosing a car engine with a clogged fuel line, you can rev the engine to redline all day long in Neutral or Park, but if you take it on the road in 2 or 3 gear Wide Open Throttle, the engine will fall flat 2 to 3k RPM and and at times stall.
Just my 2 cents!

This is exactly my line of reasoning. If it runs fine at high rpm out of the water....drain the fuel and start over.

 

[Steve Moyer]

Good point regarding load. I've had that experience in a vehicle as well. I believe my center hatch also allows access to the gas tank. I'll siphon some into a glass jar and check it out. Doesn't water sink to the bottom? Because if so, can I save the gas on top? I now think filling it up was a bad idea.....50 gallons with 25 new. It may be hard to dispose of. That's a lot of lawn mower gas, ha ha ha.

 

[Steve Moyer]

BTW, I thank you all for helping me through this. You folks are truly, a fine community I'm proud to now be a part of.

 

[Bruce]

Some have reported their engines running roughly when there was an issue with the battery or its cabling. Your low voltage warnings make me think that you should look into the battery connections.

I believe @jawsf16 experienced this in 2014.