Yamaha F115 would not stay running..

[HighTechRedneck]

Took the boat out today and my wife was pulling the boat off the trailer. The motor started up right away as normal but when she hit reverse to jump it off the trailer the motor died and would not start back up. the only way I could get it running was to throttle it up a bit but when I tried to get back to idle the engine would die out right away. I pumped the gas ball about 20 times thinking it was not getting enough fuel but it kept dieing out. I ran it for about 5 minutes at 2500 rpm and then it ran fine at idle. Later after the engine was shut down for a few hours and started right up. I checked the engine fuel filter and the float was not floating so I dont belive there was any water in the fuel. I also have a fuel water seperator installed.

Even though the engine runs fine now I was hoping someone would have some ideas of what caused it or things to check.

ANY ideas are appreshated.

thanks
HTR

 

[tfink]

Your situation sounds similar but not exact to one that I had a month or so ago. Mine would idle fine until I gave it some throttle, then it would die on me, my problem was a pinhole leak in the fuel line somewhere before the filter. When I gave it throttle the pressure would force the gas out of the pinhole starving the engine.

Do you smell gas?

 

[HighTechRedneck]

No gas smell. Just the standard damp boat smell. My wording was poor on when it initally died so here it is again in a bit more detail.

The boat was coming off the trailer at idle and when 10 feet off the my wife gave it some gas in reverse and my boat can be very jumpy in reverse. she probaly brought it up to 3 or 4 thousand RPMs so she quickly went back to idle and that is when engine first died.

I take the boat out every week so I have never primed the ball prior to starting.

thanks
HTR

 

[BarryB]

Carburator or Fuel Injected?

Hi HTR,

For carburated engines, there are two jets.

One jet is for idle and can be adjusted by the idle mixture screw. Sometimes, because the orifice is so small, a piece of debris can plug up the orifice. Result, the engine will not idle.

The other jet is used off idle and is not adjustable (except if removed and a larger or small one is installed). This jet has a larger orifice because it has to supply more fuel when the throttle is open.

If the engine is fuel injected, the amount of fuel delievered is determined by the time the injector is opened. The longer it is opened, the more fuel delivered.

So, first, what type of fuel delivery system do you have?

 

[HighTechRedneck]

BarryB

The motor is a 2005 yamaha f115. four stroke and fuel injected.

 

[BarryB]

Ok...

Fuel injected, 4 stroke.

To eliminate any fuel system problem from the tank and lines, see if you can borrow a portable tank and attach directly to the motor. If it runs with no problem, then you have eliminated the motor at the problem.

Then, it could be the fuel pickup, lines, filter, bulb, connector to motor.

Time for more work. Hope this helps.

 

[HighTechRedneck]

The big problem is I cant reproduce it again so hooking it to another tank won't help. I think I am going to replace the fuel/water seperator filter this week and hope I never have the problem again. The good thing is once the motor warmed up the problem went away and didn't come back. The bad news is its hard to find out what the problem was if it no longer happens.

thanks
HTR

 

[BarryB]

Darn little Gremlins