Engine stall out on initial acceleration

LoonLovers

Registered Member
City
Marcy
State
NY
I have a 2011 Yamaha 115 HP on a 191FS that is stalling on initial acceleration. If I start and run the engine on idle for a couple of minutes and then start to accelerate, I almost always get a stall within about 30 seconds. If I throttle back fast enough, I can keep from completely stalling out. Once the stall condition is encountered and the engine is restarted if necessary, the problem does not occur again. The problem does not appear to occur differently based on the load in the boat (2 or 7 people).

The engine is a YF115XA with about 40 hours on it. A local Yamaha dealer ran diagnostics and has found no problems or error codes. The dealer suggested solution to the problem would be to fully instrument the engine and then take it out for a few rides and hope that the stall occurs.

If I squeeze the primer bulb prior to starting, that seems to help most, but not all of the time.

When I was using 87 octane fuel (with ethanol), I was using K100 fuel stabilizer. The fuel stabilizer did not seem to make a difference.

I have been able to get 91 octane (no ethanol) fuel locally and have run about 30 gallons of that through the engine. The 91 octane and squeezing the rimer bulb has almost eliminated the problem, but not always. I plan on running the 91 octane for a while longer to see if that clears up the stalling.

I would like to eliminate this problem. It is embarrassing to show off a new boat and have it stall.

Has anyone encountered anything similar?
 

NYHarleyFisher

Contributing Member
City
Zephyrhills
Sounds to me like you may have some water or debris in the the fuel system. have you checked the water separator on the front of the engine to make sure there is no water or crap in it? I would also change your 10 micron filter. Its amazing what the ethanol fuel can do to a system. I don't know anything about the K100 stuff but have used Startron for years on both my 190 Bay and my 215CC and have never had a fuel related problem, and I run ethanol fuel all the time down here in FL. and my boat will sit for a couple of months at times with out being run.
 

LoonLovers

Registered Member
City
Marcy
State
NY
The dealer did check the water separator and it was clean. He didn't think that the filter would be the problem, since it happens once and then it is fine. I may just change the filter to see if that clears up the problem.

Thanks for your recommendations.
 

Harper

Recognized Leader Triumph 191/195 Forum
Premium Member
City
Republic of Texas
I have absolutely NO knowledge of Yamaha motors, but from my experience with other motors, Suzuki outboards, and even computer controlled FI automotive engines, the problem sounds a lot like it could be a problem with the throttle position sensor.
 

slider99

Participating Member
City
Hillsborough
I had a similar problem with my Yamaha 150, it wasn't fuel related, we cleaned the injectors, no codes were thrown. Found this on a Yamaha forum. Can't say if your problem is the same or not, but it fixed the hesitation / stalling problem on my motor.

....basically you want to adjust/make sure the two throttle assys are sync.
then open the throttle stopper screw until the TPS reads about .3-.4V higher
than with the shutters fully closed.
then reset the TPS using the TPS screws to about .72V.
when idling the ISC command should now be in the 38-45% range.
what your doing is faking out the computer and allowing some idle air past
the throttles.
 

Putershark

Administrator
Staff member
Lifetime Member
City
Pine Island
State
Florida
I had the anti-siphon valve on the fuel tank fail and create the same type of issue. Royal pain to change out and I suspect you could check / verify the same by not doing anything different, and just see "if" taking the gas cap off while this is happening actually helps? Just make sure nobody is smoking at the time or you could have a much larger problem :eek:

Picture your finger over a straw effect to help you connect the dots on this naturally ;)
 

bplaster

Registered Member
City
Washington
Had a problem with my Yamaha 150 TXR bogging down and stalling on acceleration recently. I checked and changed all the normal things, cleaned main, pilot and air jets, stopping short of removing carbs. Changed primer bulb too, but would not prime. Tried blowing into both ends of fuel line from bulb end, then engine fuel filter end but couldn't. Fuel line appeared to be clogged. Since the fuel line ran inside the corrugated conduit, along with the engine controls, I had to cut it open. What I found was the gray Yamaha fuel line had swelled from the ethanol. It had begun to delaminate on the outside, but the inside appeared to be ok at this time. It swelled so much the pressure, from pushing on the other engine controls in the conduit, created a pinch. This essentially cut off the fuel supply. Went to NAPA and purchased ABYC Marine fuel line that was resistant to ethanol. Installed this and the boat now runs like it should. I'll most likely be using non-ethanol fuel from now on. If you have these Yamaha gray fuel lines BEWARE.
 

Attachments

LoonLovers

Registered Member
City
Marcy
State
NY
Thanks for letting us know about this. I am going to check my fuel lines tomorrow.

FYI, after running a lot of non-ethanol gas through my engine and changing the water separator a couple pf times, my acceleration problems have gone away!

Thanks everyone!
 

lukebryan

Registered Member
City
Casselberry
I had the same issue with my 115 yamaha 4 stroke everytime i drove it. It would idle perfect but when i gave it throttle up at 15mph it would bog down and I found the fuel line wrapped with all the engine wiring was failing and very spongy which will allow the engine to idle good but when getting on the throttle the fuel line due to being weak and spongy would allow the hose to suck in causing the fuel line to restrict and lose fuel pressure plus I cleaned the VST.
I have ran it about 60 miles and zero issues.
 
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