Engine dieing out.

[HighTechRedneck]

2005 Yamaha f115 800 hours

So I run my engine at idol a lot trolling for salmon. It seems if I am at 1200 RPM's and I drop the throttle back to idol the engine sometimes dies out. I also had this happen yesterday while I was going 4500RPM's and dropped the throttle quickly back to about 3,000 RPM's. When the engine does die out most of the time It will not start back up unless I throttle up the gas to start it and leaved it throttled up for about 30 seconds. It seems every time im out it happens more and more but in a 6 hour trip it happens about 3 times.

Any ideas.
Do you think it is a fuel filter problem? I replaced the fuel filter about 200 hours ago and also replace the filter on my fuel water seperator at the same time.

I can stick my head in the bilge and also where the fuel water sperator is and I dont smell any gas so I dont think it is a leak.

HTR

 

[fridaysoff]

HTR,
You really should change the fuel/water separator filter every 50 hours or so.I would change the filter inside of the cowling every 100 hours. That could be the problem you are having.You run your boat often so I would think the fuel is fresh.I would change the plugs at least every 200 hours maybe more often with the amount of trolling that you do.You possibly have carbon build up with that amount of slow trolling. I would use "Ring Free" constantly in your fuel tank. I would use the shock treatment amount at first and then the constant amount. One ounce per 10 gallons. That will keep the carbon down some. Thats where I would start. Fuel treatment,filters,and plugs. See if that clears it up.Good luck.
John D.

 

[BarryB]

Question?

Is the engine fuel injected or carburated?

 

[Dave LeGear]

I would (if equipped) drain off the bowl under the Fuel / Water Separator and if not of that type, then replace it the entire filter cartage.

Also note that Yamaha Ring Free is nothing more than Chevron's Techron in a bottle (good stuff) and you can save some coins by getting it at the local Auto Parts location by picking up the "Clean Up" version. Just be careful and I would not use more than three bottles of the stuff in a row without changing the engine oil. If not, all that crud (carbon) that it removed from the valves, etc. is now flowing around in the lube oil like very tiny pieces of sand and grit and not something I would like to leave in there for very long

 

[HighTechRedneck]

Is the engine fuel injected or carburated?

Fuel injected.


THanks guys for the replys. I figured it was something to do with the fuel lines or filters. I didn't think about ring free but Yesterday I picked up a bottle of ring free and both the fuel filters.

Thanks for the heads up on the ring free dropping stuff into the oil. I also bought stuff to do the oil change and was going to do it before I put in the ring free but now it looks like I will wait awhile.

THanks again
HTR

 

[BarryB]

In the old days...

Back in my youth, I worked at a Datsun dealership. When the fuel injected 280Zs would come in for poor acceleration or rough idle, replacement of the injectors would solve the problem.

Seems, over time, varnish would form on the injector and distort the spray pattern. I don't think cars have that problem anymore, but, perhaps boats do.

If the fuel injection system works like that on cars, the system is pretty simple. A constant fuel pressure is applied at the injector, the amount of fuel injected is determined by how long the injector is held open (the pulse width). The computer receives information from sensors for throttle position, manifold pressure, temperature, crank position, etc. Something could be up with any one of those sensors or the connections (dirty?). You may need the use of a computer designed to read all the sensors while the motor is in a test tank.

Keep us informed.

 

[Dave LeGear]

280z, talk about a 8 track (more like cassette) flashback I had one myself and even loosened up the spring on the mass air flow sensor door to give it a little more "grunt" off the line

Injectors have come a long way since then and they have vibrating tips that keep most of those types of issues in check, Here again as I have stated many times, the lack of using high detergent fuels can cause one a lot of grief. The use of Techron (Ring Free) will also go a long way in keeping deposits under control IF you understand where all that junk is going and will keep your oil changes current. Little micro chunks of hard carbon floating around in the lube oil is not my idea of having long engine life with something that works under such strain and loads

Carbon build up on the valves will also create cold start issues in the South since when cold, like a sponge can soak up a lot of fuel. This does not seem to be an issue as much in the North since the ECU reads the air temp (which is naturally cooler) and dumps in more fuel (like a choke) for the first time start up. So removal of that carbon will help engine performance a great deal since the ECU is not designed or program (how could it?) to make adjustments for something (like carbon build up) it cannot measure.

Other engine sensors creating an issue is possible, but usually those will also kick off a check engine light of some kind that a data dump will then report. Those readings though I always take with some element of suspect since a loose or dirty ground wire, or even a weak start battery can produce "false" sensor readings due to the fact that the ECU is (for a better lack of terms) confused from the below spec voltage drop.

Still sounds like water in the fuel filter to me and I would be going along the path of ruling out normal service items first (filters, plugs, plug wires), then if needed, circle back and start checking grounds and battery output. I would do this long before pulling injectors and as long as one can get the engine running, fuel additives (injector cleaners) can usually do a pretty good job of cleaning up a poor spray pattern on one

 

[Pescador]

I ran a 115 Yamaha for over 3000 hours and I learned two things. First is that the factory filter of 10 micros is not enough filter to take out the stuff that can clog the injector holes. In Mexico, where we get dirtier fuel, we use a 2 micron Racor filter and the injection problems literally stopped. Second is that you may need to clean the injectors and if you are going to do that, make sure you clean the screens on the high pressure fuel pump which is located behind the intake manifold and at the same time replace the small in line filter going from the fuel pump to the high pressure pump. It is an in line filter and at your engine time is probably due for replacement.

 

[HighTechRedneck]

I ran a 115 Yamaha for over 3000 hours and I learned two things. First is that the factory filter of 10 micros is not enough filter to take out the stuff that can clog the injector holes. In Mexico, where we get dirtier fuel, we use a 2 micron Racor filter and the injection problems literally stopped. Second is that you may need to clean the injectors and if you are going to do that, make sure you clean the screens on the high pressure fuel pump which is located behind the intake manifold and at the same time replace the small in line filter going from the fuel pump to the high pressure pump. It is an in line filter and at your engine time is probably due for replacement.

A few questions
The inline filter that you are talking about. the one that I change is the filter that is in a clear cylinder on the back of the motor with a red float in it.
How do you clean the injectors and screens? I am pretty handy with engines but I have only replaced injectors not removed and cleaned them.
Where is the fuel pump? Both inside the motor?

Thank you for your response. The problem seems to have gotten better but still does happen.

 

[Pescador]

Okay, the filter you are talking about is a pre-filter and has a screw bottom where you can screw off the bottom, and replace the little cartridge inside. No, the filter I am talking about is in a hose that runs from the Mikuni fuel pump to the high pressure fuel pump which is located under the air intake manifold. If you look at the rubber fuel lines, you will find it. It is covered with rubber, so it is located only because the fuel line is swollen in the center. If you go to any of the Yamaha parts sites, you can see the tube.
The injector pump (again look at the parts websites) sits under the air intake manifold. In fact there is a screw in the bottom of the pump and I drain the fuel here if I am going to store the boat for more than 30 days.
If I read correctly, you may have put in a little injector cleaner or ring-free which would help a little, but the only way I ever found to absolutely correct the idle problem was to clean the screen in the injector pump, clean all the injectors by soaking them in paint thinner and then blowing injector cleaner through them, and changing both of the filters. Long range, you may want to consider doing the 2 micron Racor filter which every Yamaha in my part of the woods now has.

 

[HighTechRedneck]

Thank You!!!.

I have only replaced the Pre-Filter so I am sure the other filter has never been touched.. I didn't even know it was there.

 

[BarryB]

To Dave,

Yep, even worked on the 240z and 260z. Those were the times when you had to balance the carbs.

Carb. cleaner works great for removing varnish, tough on paint though. Be careful.