Why does my motor go dead?

Ronesburg

Recruit
Joined
Nov 8, 2017
Messages
2
I have a 2000 model 90hp Yamaha outboard. I just had the carbs rebuilt, new fuel filter installed, new fuel lines and new spark plugs. The problem I have (and have had since I bought it) is that I can crank it and it will run good for a minute and then just goes dead. If I idle it up it will run but as soon as I idle down it goes dead. Now once it finally warms up after many attempts of cranking/idling up for a few minutes it will run and the rest of the day I can cut it off and it will crank back and run with no problem. I do not believe it is "just cold natured". What am I missing?
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
I was leaning towards fuel pump but if she will run the rest of the day its not the fuel pump.
It's a wire.A wire is corroded in a wire connector,pull all wire connectors hard to see if the connector pulls off, a wire has a bare spot and grounding out on something.Check every inch of wire. We had a Force 125 and a green trigger rubbed on the flywheel made a 1.25 inch bare wire,started great cold at the ramp but when she warmed up resistence increased started shorting out and motor died.Happy ending though wife made me sell the boat, we got a mako 22 with twin 115hp EFI she's a beast.
Do you have a way to read error codes.
Get a factory service manual and start studying.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
this is a prime start motor so it auto enriches fuel during cold starts.
then drops off when motor warms up.
or at least the CDI is told it has warmed up by a temperature switch.
maybe that is not working as it should, or could be the carb was not cleaned properly and set as it should.
If it was mine I would make whoever did the carbs do it again on their dime since it is not working properly.
was this work done by a Yamaha shop by experienced techs that know what they are doing?

Most good shops will also replace the fuel pump when doing a carb job to keep trash hiding in there from hitting the cleaned carbs
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Mmm. Strange one. Could be a few things I suppose.
Perhaps choke related ?
 
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