f115 surges

[tundratoad]

Have read most all the post about yamahas surging and it appears no one has ever fixed this problem. Or at least that would seem to be the case since no one has posted what they did to fix the problem. Lots of people seem to believe this to be a fuel problem and it does indeed smack of that my problem with that is, if you have a fuel problem one minute and you don't do anything to fix it, how does it go away the next minute, or less? What I am referring to is the difference in my problem and other post on this issue. My engine can be surging violently when the throttle is advanced. But if you turn the ignition off return the throttle to neutral and restart the engine might very well take off just like nothing was ever wrong with it. To me, this does not fit the fuel supply, or fuel quality failure characteristics I am familiar with. This problem screams brain box to me, that is why I changed the ECU but I still have the problem and it is the exact same problem. I have done a lot of things to this motor to include all the recommendations previously posted. What I am hoping iis that someone has in fact fixed this problem and can will see my post and tell me what they did that fixed it. I am really at my wits end with this thing. And please tell me what a VST tank and or filter are there is a ton of dialoge about them and I seem to be the only one that doesn't have a clue what is being talked about. Everything I can find with regard to fuel has been cleaned changed or otherwise inspected, bypassed or thought to be performing as advertised.

Thanks a ton for any help anyone will be so kind as to offer.

Herb

 

[99yam40]

Re: f115 surges

It would help others if they knew what your model #is
if your motor is carbed it will not have a vapor separating tank, but it will if it is fuel injected.

monitor fuel pressure/vacuum to see if you have a supply problem

 

[tundratoad]

Re: f115 surges

Can't know what I am doing wrong but I responded to the Rear Admiral yesterday, it looked like it was posted but now I don't see it anywhere. I will try again.

I realized I should have better identified the motor after I had posted. Thanks so much for your kind and timely response I will give you some more info on the motor and what I have done to attack this problem. This time I will save this on a separate file so I can paste it in case it doesn't get posted again.

This is a four stroke 115 hp Yamaha factory jet built in Jan of 2000 I bought it used four years ago and it has ran flawlessly up until this spring. I live in Alaska so it only gets used in the summer. This summer, things went south right from the beginning. It began surging from jump street. Found water and rust in all the filters including the injectors, (much to my surprise) it had to get past two filters to get to the injectors, never thought it could do that but it did. I cleaned the injectors as best I could, changed all the filters I could find. That being the racor and the one near rear of the engine close to the fuel pump. I thought that had cleared the problem after running the engine for about an hour afterward it ran fine. The next trip, it was back to surging again. Cleaned the injectors again but really did not find any obvious particles. No change in the way the engine ran, still surging. Changed all the filters again. No change in the way it ran. Unlike some others who have had this problem pumping the bulb has no affect on the way the motor runs when it is surging. Also unlike other post this problem will go away completely by turning the motor off and right back on. Or I should say it will clear the problem "some time", some time it will return to it's surging ways. But if you keep trying this procedure it will take off and run for a period of time, but if you move the throttle it will again bog down and surge. And when I say surge I mean it will surge markedly depending on how much you advance the throttle. I have changed the ECU. I have changed the bulb, the spark plugs, the thermostat, and I have disconnected all the sensors I can find. Oil, heat, air and throttle position without effect. It still does the same thing, including running well for short periods of time. I don't see any difference in engine performance with the Throttle position sensor connected or not. I have ordered another one. There is a small amount of oil present in the air box, I am taking that off today to see if I can see what that might be about. I have no idea how many hours are on the engine. I have put about 150 hours on it in the last four years or so. I am sure it would have triple that or more.

No, I have not pursued the fuel side of this issue beyond the filters and cleaning because I don't see how fuel problems clear themselves by turning the ignition off and back on. But I am getting close to being at my wits end about this and will try anything.

 

[99yam40]

Re: f115 surges

still no model #

Is it a 115TJRY?

need to get it hooked up to a computer for proper diagnostics
Disconnecting things is not the right way to troubleshoot.
ECU needs their inputs for proper running
Monitoring fuel rail pressure will tell if it is in spec(not too low or too high)
Injectors and pump have screens need to find and clean or replace all filters and screens, so need to find them all.
Rust in injectors could be from pump rusting in VST, did you open that up and clean everything

 

[hawilson2]

Re: f115 surges

Not sure if its the same issue, but I had a 2006 F115 that was bogging on acceleration at times. Sometimes, would run and get to full throttle and it would bog and surge and maybe even eventually die. Along the way I replaced the fuel filter, external fuel/water separator filter and the VST filter. Had the injectors professionally cleaned which included replaced their filters. Did all this pretty much all at once so not sure exactly what fixed the issue but I have not experienced anymore problems since. Hope this helps.

 

[tundratoad]

Re: f115 surges

It does indeed help, that is exactly what I have been hoping to hear. Someone who has had the problem and cleared it. It sounds exactly like the problem I am having, the only thing missing is the part about turning the engine off and restarting it right away. I don't suppose you tried that or you would have mentioned it. I have done every thing you talked about (twice) except having the screens/filters changed in the injectors. I have ordered a new Throttle position sensor and it might be in the mail today. If that doesn't clear the problem I am going to take the injectors out and send them off to have the screens changed. Thank you so very much for your response, If there is anyone else who has corrected this problem please advise of corrective action. it has been suggested I hook the engine up to the computer to diagnose the problem. I tried that, I took it down to the local Yamaha shop, Dewey's Cook Inlet Marine. Specifically told them what I wanted them to do, that being to hook it up to the computer and see if it would show any sort of electronic failure. They changed the primer bulb, spark plugs, thermostat, and ran it at idle and said it ran fine. They charged me 359 dollars and did not hook it up to a computer, I presume they didn't hook it up because they didn't charge me for it. and the service manager suggested I might have a bad ECU. They won't see my boat again, you can bet on that. If anyone knows of a program I can buy that will diagnose this engine please advise Dewey's is the only show in town and I don't believe they have the capability. And for what it cost me to drag this thing to Anchorage and back I could probably pay for the program and have it the next time something goes wrong.


Thanks a ton for your response
Herb

 

[tundratoad]

Re: f115 surges

Sorry guys, it is a TLRY model engine.

Herb