# Yamaha 25hp 4 Stroke help



## Brett (Jul 16, 2008)

I think your fuel system isn't functioning properly.
My guess, without any further information, is that something
is restricting the flow of fuel to the carb(s).


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## wadeleebenton (Apr 8, 2009)

Any ideas on where I should start checking first?


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## Brett (Jul 16, 2008)

Fuel lines from tank to carb(s).
Airleaks, blocked filters, bad fuel pump, sealed fuel tank (vent not open)

My troubleshooting checklist from a previous post:


> When an outboard acts up, it can be the most frustrating thing to deal with.
> But the rules are simple...Air, fuel, spark, timing, compression, cooling, lubrication.
> Any of the items listed above can affect how your outboard runs.
> 
> ...


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## DuckNut (Apr 3, 2009)

I would not be looking for an obstruction because you mention that it eventually gains rpm's and it takes less time when warm. My guess is that the little gasket around the needle vlave in the float is rotting and turned to a gummy substance and is sticking.

Take the bowl off and remove the float and the needle valve and remove the o-ring and reassemble and start. If you get rpm's right away that was your problem. Your motor will not idle down or run right with this piece out, but it may give you a starting point. Some carbs have a rubber tip on the valve - if this is yours then clean it well and spray some cleaner where it seats and reassemble and test. Either way it is a 10 minute experiment.

The o-rings are made from two types of material; neoprene and rubber. Neoprene rings are not long lived with gas.


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## wadeleebenton (Apr 8, 2009)

Thanks guys! This will give me a start on a weekend project.


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## wadeleebenton (Apr 8, 2009)

So how do I pressure test the fuel pump? I'm pretty sure thats my problem but want to make sure before I get a new one.


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## Brett (Jul 16, 2008)

http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1300667925/5


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