1985 yamaha 90hp

knight_time

knight_time

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when i was fishing last weekend the motor would idle fine at the dock and seemed to be running fine when i tried to shift into gear it would die. after i got it running the motor would increase and decrease rpms without me touching the throttle. my buddies and i tossed around the idea of it being a float value, carbs being out of sink, or a vaccum leak. my question is has anyone else had this problem? i can fix a vaccum leak and change float values, but i dont know how to sink 3 carbs any advice wold be much appreciated
 
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robert graham

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Re: 1985 yamaha 90hp

Drain each carb onto a clean white rag to see what's in them. With drain plugs out, pump primer bulb to flush each carb and float needle valve. Your problem does sound like a fuel delivery issue, so start at gas tank pick-up tube, then to primer bulb/check valves, quick disconnect fitting on front of motor, fuel filter/o-ring, fuel pump. Pump primer bulb hard and check for fuel leaks. If all these are fine then you may need to have carbs cleaned. Good luck and let us know what you find.
 
knight_time

knight_time

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Messages
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Re: 1985 yamaha 90hp

robert graham said:
Drain each carb onto a clean white rag to see what's in them. With drain plugs out, pump primer bulb to flush each carb and float needle valve. Your problem does sound like a fuel delivery issue, so start at gas tank pick-up tube, then to primer bulb/check valves, quick disconnect fitting on front of motor, fuel filter/o-ring, fuel pump. Pump primer bulb hard and check for fuel leaks. If all these are fine then you may need to have carbs cleaned. Good luck and let us know what you find.
Click to expand...

thanks for the help going to tear into it tomorrow and see what i find
 
knight_time

knight_time

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Re: 1985 yamaha 90hp

think i found my problem what is this and how much do they cost?
 

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robert graham

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Re: 1985 yamaha 90hp

You can order a fuel pump online or from your Yamaha dealer, but are you sure that's the problem?
 
knight_time

knight_time

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Messages
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Re: 1985 yamaha 90hp

robert graham said:
You can order a fuel pump online or from your Yamaha dealer, but are you sure that's the problem?
Click to expand...

it was jb welded on and squirting gas out of it when i primed the buld. im not sure thats the only problem but it cant be helping at all and needs to be fixed regardless.
 
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robert graham

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Re: 1985 yamaha 90hp

Yep, that's almost for sure your problem, very easy fix. I saw something dark in your photo but couldn't tell what it was. Why would anybody try to JB Weld a $50 fuel pump, knowing it's just going to fail down the river somewhere? My motor is a 1999 and I just put a new fuel pump on a couple of weeks ago just to be sure, kept the old original pump(which was fine) for a spare. Good Luck!
 
knight_time

knight_time

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Joined
Dec 21, 2009
Messages
37
Re: 1985 yamaha 90hp

robert graham said:
Yep, that's almost for sure your problem, very easy fix. I saw something dark in your photo but couldn't tell what it was. Why would anybody try to JB Weld a $50 fuel pump, knowing it's just going to fail down the river somewhere? My motor is a 1999 and I just put a new fuel pump on a couple of weeks ago just to be sure, kept the old original pump(which was fine) for a spare. Good Luck!
Click to expand...

One of the fuel line connections was broken off so I have a feeling someone jb welded it to keep from having to buy a new fuel pump. Hopefully that is the only thing ill have to fix, Thanks for the help
 
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