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Author Topic:   1989 Yamaha 90-HP

gobama posted 01-26-2012 03:52 PM ET (US)
[The] best engine I ever had[--a 1989 Yamaha 90-HP three-cylinder two-cycle outboard] now has a couple of [problems]. After [the 1989 Yamaha 90-HP] fires up and idles for a couple minutes, it dies and is hard to restart. The problem seems to be only idle and low-RPM related. Once you get her going at high RPM, she runs great. Then throttle down to idle and dies on me again. I replaced the plugs recently. [Do readers think that the carburetor] jets need cleaning?
tjxtreme posted 01-26-2012 04:28 PM ET (US)
Thats what is sounds like. Try adding Seafoam if that is your thing, or the next step would be to rebuild the carb.
L H G posted 01-26-2012 04:39 PM ET (US)
Clean and overhaul the carbs as mentioned. Reset idle speed. If idle is still weak and engine wants to stall going into gear, your problem is reeds or reed cage wear on the crankshaft, requiring a tear down.
Peter posted 01-26-2012 06:02 PM ET (US)
When was the last time the fuel lift pump was replaced?
gobama posted 01-27-2012 01:39 PM ET (US)
I've had the 65 Nauset with that motor since [2005--please use four digits for years instead of an apostrophe and two digits] and nothing has been done to the engine other than a water pump in [2005] and spark plugs last year.
Peter posted 01-27-2012 08:06 PM ET (US)
Treat your motor to a new lift pump.
jimh posted 01-27-2012 09:40 PM ET (US)
I would not give a moment's thought to the reeds until you have explored the more obvious and more common problems and their simple remedies, as others recommend.
Russ 13 posted 02-01-2012 06:39 PM ET (US)
I too have a Yamaha 90HP, 2000 model.
I second the:
1) clean & properly adjust the three carbs.
2) replace the fuel pump.
3) clean the fuel filter
4) Make sure the gas is new & fresh.
5) install a new set of properly gapped plugs.
I have had good results with NGK, but check the gap with a
gauge, as sometimes they are not exactly the same.
Before going any deeper into the engine.
If it ran good, and then this problem just started, I
think the above will get you back to 90HP Nirvana.

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Author	Topic: 1989 Yamaha 90-HP
gobama	posted 01-26-2012 03:52 PM ET (US) [The] best engine I ever had[--a 1989 Yamaha 90-HP three-cylinder two-cycle outboard] now has a couple of [problems]. After [the 1989 Yamaha 90-HP] fires up and idles for a couple minutes, it dies and is hard to restart. The problem seems to be only idle and low-RPM related. Once you get her going at high RPM, she runs great. Then throttle down to idle and dies on me again. I replaced the plugs recently. [Do readers think that the carburetor] jets need cleaning?
tjxtreme	posted 01-26-2012 04:28 PM ET (US) Thats what is sounds like. Try adding Seafoam if that is your thing, or the next step would be to rebuild the carb.
L H G	posted 01-26-2012 04:39 PM ET (US) Clean and overhaul the carbs as mentioned. Reset idle speed. If idle is still weak and engine wants to stall going into gear, your problem is reeds or reed cage wear on the crankshaft, requiring a tear down.
Peter	posted 01-26-2012 06:02 PM ET (US) When was the last time the fuel lift pump was replaced?
gobama	posted 01-27-2012 01:39 PM ET (US) I've had the 65 Nauset with that motor since [2005--please use four digits for years instead of an apostrophe and two digits] and nothing has been done to the engine other than a water pump in [2005] and spark plugs last year.
Peter	posted 01-27-2012 08:06 PM ET (US) Treat your motor to a new lift pump.
jimh	posted 01-27-2012 09:40 PM ET (US) I would not give a moment's thought to the reeds until you have explored the more obvious and more common problems and their simple remedies, as others recommend.
Russ 13	posted 02-01-2012 06:39 PM ET (US) I too have a Yamaha 90HP, 2000 model. I second the: 1) clean & properly adjust the three carbs. 2) replace the fuel pump. 3) clean the fuel filter 4) Make sure the gas is new & fresh. 5) install a new set of properly gapped plugs. I have had good results with NGK, but check the gap with a gauge, as sometimes they are not exactly the same. Before going any deeper into the engine. If it ran good, and then this problem just started, I think the above will get you back to 90HP Nirvana.