115 hp yamaha not getting fuel?

Evil Eye

Cadet
Joined
Sep 3, 2001
Messages
7
I have an 87 115hp Yamaha outboard. The problem that I'm having is that whenever I give it a lot of throttle, it starts killing on me and I have to back it off to keep it running. I can get it up to about 50mph sometimes but as soon as I get going that fast it starts to die. It never completely kills. It runs perfect at low speeds. It doesn't seem to be missing at all, it just sort of bogs down. It's kind of jerky. To me it seems as though it's not getting enough fuel. I took the fuel filter out and it was as clean as a whistle. I don't know if you can tell by looking at them. Also someone told me to try unscrewing the gas cap while driving to make sure it's not an airflow problem. I tried that and it did nothing. I am very new to boat motors and really don't have a clue what to try. I would appreciate any advice. Thanks.
 

TONY H

Petty Officer 2nd Class
Joined
Jul 2, 2001
Messages
115
Re: 115 hp yamaha not getting fuel?

What is your RPM at 50 MPH? You say you are new to boating, If this is a new boat to you, the Previous owner may have downsized the prop. If the Yammy's over rev, they will cut back. It's a safety feture that they started around '87.
 

kevlar3000

Petty Officer 2nd Class
Joined
Mar 20, 2001
Messages
194
Re: 115 hp yamaha not getting fuel?

If all is operating in the normal rpm range, I would replace fuel hose and bulb, as well as rebuild the fuel pump. If you have an inline fuel filter try moving it below the primer bulb if it is not already there. Make sure all fuel line connections are snug as well. I would start simple and go from there.<br /><br />Good Luck!! ;)
 

OBMD

Seaman Apprentice
Joined
Sep 2, 2001
Messages
46
Re: 115 hp yamaha not getting fuel?

How much do you use this motor. Yamaha carbs get plugged up easily. Possible carb job in the future.
 

Evil Eye

Cadet
Joined
Sep 3, 2001
Messages
7
Re: 115 hp yamaha not getting fuel?

Well I don't know if this makes any sense but after taking the fuel filter out and cleaning it it runs great. I took it out today because I was going to try to prime it when it started to kill. Well it never started to kill. The thing ran great the whole time not matter what speed or rpm. It maxes out around 5500 - 6000 rpm. It did this once before. When I first got it, it ran fine. Then it started to do what I said before. Then I put premium fuel in it and it ran great for a while. Then it started doing it without changing the fuel. Now like I said after cleaning the fuel filter (which just consisted of running water through it, wiping it off and blowing it out) it runs perfect. Can anyone figure this one out?
 

Evil Eye

Cadet
Joined
Sep 3, 2001
Messages
7
Re: 115 hp yamaha not getting fuel?

By the way, should I be running premium, or should I just be using regular 87? I don't mind paying a little extra if it is better for the motor.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: 115 hp yamaha not getting fuel?

87 Octane alcohol free unleaded is what Yammy wants you to burn, Eye. There is no agreement whether premium is bad for your engine. I am one who believes it is. The additives used to raise the octane can promote extra deposits, and premium burns at a not-ideal temperature.<br /><br />Only if your engine is so carboned up that preignition is a problem will premium do you any good, and decarbonizing will do you more good, cheaper.<br /><br />Red sky at night. . .<br />JB :)
 
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