# 2002 Yamaha F115 four stroke



## jman (Oct 5, 2007)

Hello all,

I recently purchased a boat with this motor on it and it runs great, gets on plane, cruises, and WOT's fine. Only problem is it doesn't want to idle. Already took IAC valve off and cleaned thoroughly with carb cleaner as most people suggested. Could it possibly be bad? Are there any other suggestions out there? I wasn't worried about this problem until it stalled on me three times trying to get it on the trailer saturday. Any suggestions are greatly appreciated...

Thanks in advance,
Josh


----------



## stauty trout (Jul 19, 2012)

Is this a fuel injected 115 or still carb


----------



## jman (Oct 5, 2007)

This is a fuel injected model...

Thanks,
Josh


----------



## stauty trout (Jul 19, 2012)

It could be the screen on the pickup up fuel pump on the VST... The screen on the pick up is tiny... Say the size of an eraser on a pencil... Does it ever seem starved for fuel when running? My motor when I first got it (07 115 Yamaha 4-stroke) would run great at times and other times seem starved for fuel (stall out, wouldn't get on a plain, idle funny)... Took the VST off and replaced the screen (which was almost completely clogged) and it runs like a dream now... Also had my injectors cleaned when I had to remove then to get to the VST... Not a difficult task... You just have to pull off the intake manifold


----------



## jman (Oct 5, 2007)

*2002 yamaha 115*

Stauty traut,

My problem doesn't have any of those symptoms. It doesn't hesitate to get on plane or run WOT. The only problem it has is idling. I am going to check fuel pressure at the top of the fuel rail. This will eliminate the VST if pressure is good. All of that has been done by Davlor Marine anyways. It still could be the internal screen inside the high pressure pump. The test will reveal. Could my problem still be the VST? Thanks for the suggestion.

Josh


----------



## stauty trout (Jul 19, 2012)

I doubt you would ever have to replace the whole VST unless it was cracked... maybe just the gasket on it if the pressure is a little off or just replacing it if you decide to open it up to replace the screen.. I didn't mean to suggest replacing the whole thing... just the screen on the high pressure pump inside of the VST... Sorry if my last post was confusing I was typing on my phone... The cap/screen for the high pressure pump is cheap and is a common problem with those motors because the pickup area is so small and will become clogged easily...


----------



## jman (Oct 5, 2007)

*2002 yamaha*

Thanks,

I will check that as well as the injector screens.

Josh


----------



## TheCaptKen (Mar 14, 2011)

If it runs well otherwise then the fuel system is fine. I've replaced a bunch of those IAC units.


----------



## jman (Oct 5, 2007)

*2002 Yamaha*

I ran the motr and let it stabilize. Removed the iac and watched it extend. After the motor shut off The iac valve retracted. Checked fuel system and after the high pressure pump was 42 psi. The pressure would bleed off but fairly slowly. I am now going to check for bleeding injectors and pressure regulator. Could the iac still be the culprit if is operating? Or should I be looking more at injectors or regulator? Also when cleaning the injectors, carb cleaner would seep from the strainer to the pintle. I'm nervous that this means I have leaking injectors. What do you guys think?

Josh


----------



## The Maintenance Shoppe (Nov 5, 2007)

I have a fuel injector flow bench, I can test the injectors for leakage. 221-1875


----------

