motor running rough

[Leon Gus Nichols]

I have a 2005 Yamaha 150hp 4stroke on a 197 Pioneer. Runs a little rough on trailer and terrible in water under power. While idling on the trailer motor shut down and would not start until gas ball was squeezed. My mechanic said gas is bad and I should drain all 70 gallons out. I prefer to attempt other solutions first. Other than water separator and bowl where are other filters?

[robert graham]

Take a sample of fuel in a clear glass container and look and smell of it....if it's bad/deteriorated it will be cloudy and have a bad smell...then you'll need to remove all of it and clean/flush your fuel system....all filters must be cleaned. A manual for your motor would help you do this or take it to the Yamaha Outboard dealer for service....A fuel stabilizer like Stabil or Seafoam will help prevent the rapid break-down and deterioration of fuels stored for several weeks/months...

[TownsendsFJR1300]

The main, initial fuel filter on your motor is under the cowl, literally facing you when your aboard.

The filter housing should be clear plastic when new but is likely yellow now. You'll also see a red ring inside tha assembly. The red ring rises if there's any water trapped in there. There's a SS locking lever you flip up, you can then unscrew the plastic nut and the cup will come off. The filter sits up inside of there.

Be forwarned, that plastic cup (above mentioned), with ethonol fuel, tends to expand and not seat back in the upper housing. I had to replace mine under warranty as it literally expanded, not much, but enough that it wouldn't seat. If it doesn't slide easily back up inside, just replace it or you'll have a fuel vacuum leak.

Note, there has been a re-call on this engine for the balancer (it literally sits behind that fuel filter). Even if its out of warranty, if its original unit, Yamaha will relace it with an updated unit for free. There have been several updated units over the years. Takes about a half hour to change out