Yamaha T9.9

[SylvanTroller]

I recently boat a 1993 Yamaha T9.9ELRR it was starving for fuel and not running correctly. These motors are notorious for fuel pump issues and Yamaha has since developed a pump with a heat sink and cooler for them. I picked up the new pump (around 100 bucks) at Brobiel Marine (Frans a great guy). Replaced the pump and she was running only slightly better and still sucking the filter dry.
 
I ripped out the connections and fuel line and ran a new line straight to the tank. Same thing.......... I read somewhere that a clogged crank breather could cause this issue. I pulled the breather line (see pic 1) and sure enough it was clogged with a mud wasp nest or something. Cleaned it out, checked inside the breather and other lines. Everything is clear and she is running great now. Hope this helps someone out one of these days.
 
 
 
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[Sk8man]

Good tip. Here's another: When boats are stored during the winter with outboards sometimes spiders get into the hole where water is supposed to spurt out from the water pump on the drive unit. First time out in the Spring when the engine is started person thinks they have a problem  with the water pump/impeller when no water sprays out. May be spider nest in the hole. Good idea to carry a piece of wire on the boat "just in case" and open up the hole....back in business