2003 F115 Yamaha High Speed shutdown

[CatchNSun]

I have a pair of F115 Yamaha four stroke outboards. Never had a single problem until now. 340 hrs. Intermittent shut down of Port engine at cruising speed 4300rpm. Almost a complete drop in rpms. and barely idling or shut down altogether. if I wait 5 min. runs again no problem. This is now becoming consistent after the 4th time. If I run for 4 or 5 miles it happens. Changed the plugs, fuel separator filters, oil and filter after the first time. Needed it anyway. I thought it was plugs or water in fuel (no water found in filter). Talked to dealer. He wants to blame it on Ethanol gas. Pull my fuel injector pump and clean it from some dirt and ETCHING in the boul ??? Cost $500.00 plus drain 140 gal fuel tank and clean entire fuel system $??. The Starboard engine has no problem I cannot believe this will fix my problem. I have checked the Coils and ignition is not likely the culprit. I think it is an electric problem though.
Any help would be appreciated.
Thank you

 

[rodbolt]

Re: 2003 F115 Yamaha High Speed shutdown

your describing a typical clogged vapor seperator screen due to trash in the fuel or resin from a plastic tank or a fuel level float. got 2 04 boats in the shop now with dissolveing polypropalyne tanks and both fuel level sender flosts are dissolveing.
once dissolved the resin will pass right through any filter, once the fuel is at the engine the heat and the fuel vaporizing in the intake the resin now falls out of solution and sticks to everything.
throttle sutters,intake tracts, and intake valve stems and piston rings.
ethanol is wonderful stuff, however it belongs in my tumbler with Ice not in my gas.
every one knows gas and alcohol doesnt mix, weve been told it all our lives.
actually it does mix, tastes nasty.

 

[hobohro]

Re: 2003 F115 Yamaha High Speed shutdown

Could be the same problem I had that was solved with a new ECU. The engine now runs better than it ever did.

http://forums.iboats.com/showthread.php?t=274234&highlight=f115


BTW...The failing ECU was a 68V-11 and the new one is a 68V-14. So they changed something. ie...program, components, etc.

 

[rodbolt]

Re: 2003 F115 Yamaha High Speed shutdown

a quick run or use the proper test wheel with the rail pressure guage is just to simple and will eliminate or confirm VST fuel delivery issues.

 

[CatchNSun]

Re: 2003 F115 Yamaha High Speed shutdown

Thank you for the fast response. However I just looked. I'm not good at this. Further discussion tells me it is the fuel (Ethanol) as well. Is the Vapor Separator screen in the Fuel Injection pump? I have been told this is where the problem is most likely. Is there any inlne filter that I can purchase that will prevent this in the future or just stop using ethanol.