Make sure all of the 'jets' are clean be sure and count the revolutions of your screwdriver when u open these as they control the fuel air mixture.

Try holding ur hand over the air intake to increase the fuel air ratio see if this makes it last any longer

Flush the fuel line

I had the same problem with my generater after I cleaned the jets she cranked beautifully.

2 cylinder 2 stroke? if so its an easy and dependable carb. did you blow out each and every passage ( hole in the castings) . If not do so remove jets and blow them out too. are you sure gas is getting to the carb? ethanol in gas and even the non ethanol gas just isnt what it should be . I triple dose my outboard and generators and chain saws and blower and weedeater with marine stabil. it helps

pull the hose coming from the fuel pump to carb and try cranking, it should shoot gas out with each crank, if not it could be the fuel pump, or further back. check ur bulb and fittings first before changing pump if its not throwing gas.

I had the same thing happen on a 50hp yamaha.I was that needles were stuck closed so no fuel was in the fuel bowl. Remove fuel line from fuel pump make sure its pumping.Just remember it will not pump much when u just use starter.So as long it is pumping its ok. Then remove fuel bowl from carb. if it is dry it MAY be the needles are stuck.If it was full then check the jets.ITS is defitently a fuel problem!!!!

as mentioned its not getting fuel if spraying into it gets a reaction.

you can clean the float and the float bowls but if you dont unscrew the jets inside the float bowl then you cant clean the pinholes in them to restore fuel flow.

there is also a small filter screen on most carbs under the float needle seat so remove it and check and clean this screen.

a cheaper way to clean carbs is to completely disassemble and soak them submerged overnight in 97% iso-alcohol then clean off the parts with a lint free rag and use a toothbrush to clean any remaining residue and spray carb cleaner in the passages to blast them clear, your carbs will be clean as brand new after. its safe to do this with alcohol but if you tried it with liquid carb cleaner it would harm the plastic and rubber parts.

its just dirty and needs a complete thurough cleaning of everything. now is also a good time to replace the fuel lines and hoses under the cover on the engine, its something worth doing every 4 or 5 years.

Been having boat problems for many years and 95 percent of time is a gas problem. My last problem was two bad gas tanks. New tank no more problems.

I think y'all are right. It's a gas problem. Im not getting gas to the carbs. When a pull the line off the carb and pump the ball gas shoots out. However the carbs are dry. Could it just be the fuel pump? I'm gonna try to work on it again this week. Thanks

...always keep in mind using all that quick start stuff...engines will start but they will get 'hooked' on it...cheers

crank the engine and see if the pump throws gas, if it does, then you gonna need a carb kit. like said above your float needle will get hung up, because of ware, some times you can pas a lil superfine sandpapaer on the edges of the needle and seat, but it doesnt work you put it all together for nothing the kit is cheap. the problem is the float needle and seat.

Gaspard right about the needle...the real wear comes from a mechanic duplicating a bad habit and going too tight when setting...when he backs-off for adjustment it leaves a scared seat and a duller needle...believe me they do have some dumb bunnies in O/B shops charging the max for midget 'knowledge'...(Saturday nite cheers)

P/S..also a lot of people use a white plastic protective spiral wrap on fuel line from engine to bulb and from there to the tank connection and a sliding white sleeve over the bulb...the lack of sunlite will more than triple the life of the whole system, plus cool gas going into an engine works better !!!...it's all relativity ???

i have the same motor and had the same problem we put 17 hours in it trying to figure out what was wrong and it was the fuel pump diaphram its a 12 dollar piece and thin as a piece of paper but it made it run like it was new. Trust me on this

Since you have already cleaned the carbs and put a kit in it and it still will not run, it will either be the fuel pump itself or you might have a small pinhole somewhere in the fuel lines....a lot of time the bulb will crack, it will still push out gas when you pump it but it sucks air when the motor is cranked and it will die . try replacing the fuel line or just the bulb .

Thanks for all y'all input. I put a carb kit in it, cleaned everything out and changed the diaphragm on the fuel pump. The diaphragm was the problem. It now cranks right up. Only other issue I'm having is keeping it idle. How do you adjust the idle on a 25 yamaha 2 stoke?

its usually on the cable connection, look for a screw threads on the plastic connector and there is an adjustable keeper you turn to set the throttle stopping point.

if not then it may have a little adjustable stop screw on the carb linkage, its going to be one of those two setups

Glad u got it running most people would never think about the diapfram i waisted so much time on mine that i was about to dump it in the river then to find out it was a little cheap part to fix it

careful when adjusting the idle not to use the wrong one and adjust the timing arm, make sure it only affects the flap on the carb.