2008 Yamaha F150 running rough

[kingmike]

Took my boat out for a spin the other day after sitting up for 3 months and seemed to run as well as always. At the end of the run however, the engine started jumping some and I noticed that the fuel gauge was on empty. Loaded boat up and put in 10 gals and tried today - it jumped and even backfired once and would not go over about 3 mph without trying to go dead. I haven't run this boat very much since I got it last year (maybe 40hrs) so I don't know what this could be - I have changed the fuel-water separator filter and the oil & filter back in the summer, but I wonder if water in the fuel could be the problem - I don't have the water in fuel alarm on mine. The engine is jumping bad today - Does anybody have any ideas on where I could start to figure this out? It is fuel-injected so no carb. to adjust, haven't checked spark plugs or anything.

 

[rodbolt]

Re: 2008 Yamaha F150 running rough

how do you know its an 08 model?
anyway your describing either debris in the VST or injectors.
you can either run it with the diagnostics hooked up and a fuel rail pressure tester or clean the VST,replace all filters,flush all fuel lines and rail and have the injectors serviced.

 

[Pez Vela]

Re: 2008 Yamaha F150 running rough

When I remove the engine cowling on my F150 my heart beats fast, my eyes glaze over and I feel dizzy. Guess I'm not much of a mechanic. I don't even know what a "jumping" engine is. You have received some expert advice already ... now here's mine: check to see if your engine mounted fuel filter has "miraculously" loosened itself allowing air to be sucked into the fuel lines. I wouldn't have believed that it could be possible ... if it had not happened to me. Please tell us what you find. Thanks.

 

[kingmike]

Re: 2008 Yamaha F150 running rough

Well I'm not much of a mechanic either - I have no idea what the VST is. Anyway, I said my engine was jumping because it was the best way to describe it. I am planning to change the fuel filters and drain fuel line. The fuel filter inside the cowling has never been changed because I can't twist it off - or maybe I'm not doing something right to get it off. Thanks for the advice, I'll let everybody know what I find.

 

[rodbolt]

Re: 2008 Yamaha F150 running rough

you should have done it BEFORE they passed the debris.
simply cannot put 5 pounds of sheet in a 2.5 pound container.
it will overflow and send the debris on down the line.
what your describing is a lack of fuel in the cylinder,I see it a lot.
there is a filter mounted on the front of the engine,if yours is actually an 08 manufactured motor the cup will have a two wire connector on the bottom.
yes Ethanol swells the cup making removal difficult and usually reinstallation impossible.
more on that later.
there is another 10 micron filter located on the Vapor seperator inlet,requires intake manifold removal to access.
there is another small filter located in the vapor seperator tank, attached to the high pressure fuel pump,requires intake manifold removal then removal of the VST from the intake manifold.
each injector has a filter at the injector inlet,requires fuel rail removal then remove the injectors from the rail.
if the rubber orings at each end of the injector are not damaged they can be reused.
injector filters on that engine are NOT field servicable.
a simple fuel rail pressure test can find the issue rather quickly but we see this a lot.
takes about 1.5 to 2 hours to service the VST and flush the fuel rail and injectors.

now on the filter cup, occasionally I have to remove them with a strap wrench,threaded models only, then once the cup is off leave it on the workbench overnight and the next day it will fit again.