hard start

[fisherman363]

My 1998 Yamaha 25 hp 2 cylinder 2 stroke outboard is hard to start after sitting for a few days. I pump the primer bulb witch is usually hard, pull the manual choke out and set the fast idle lever for hi idle. It will take quite a few cranks before it will fire. If I spray a little gas directly into the carburetor it will start right up. Once it fires it will it will fire immediately for the rest of the day. Pumping the primer bulb does move gas thru the gas filter to the fuel pump. I'm guessing It's the fuel pump but the engine runs fine at all rpm's and has plenty of power. it's just a problem after sitting for a few days.

[99yam40]

are you sure you are pumping the bulb enough to get the carb bowls full?
with My C40TLRX I can hear the fuel flowing thru the pump check valves and will finally stop leting any more flow once carbs are full

[fisherman363]

I've disconnected the fuel line at the fuel pump and pumped the primer bulb and get plenty of gas flo.

[99yam40]

I was trying to say, are you sure the carb bowls are full when you stop pumping the primer.
pumping until the bulb is firm may not mean there is enough fuel in the carb bowl for the motor to get the fuel it needs to start.

some have a different thought on how much to prime the fuel system.

pump until nothing is flowing anymore.
and then try starting

[fisherman363]

Thanks for the input. I'll remove drain plugs from carburetor fuel bowls and make sure I have gas there and get back to you with an answer.

[99yam40]

just becaue you have a little fuel in there does not mean it if full like it should be,
takes some time for the pump to fill it up properly if you do not do it while priming.

why not just pump the bulb until you cannot get any more thru it and try starting?

[fisherman363]

I always pump the bulb until it's hard and it stops moving gas. I guess my question would be- the engine starts right up all day after the first start. Where does gas go when the motor sits for a couple of days. This problem just started at the end of last season. I assume with the fuel bowls drained gas would flo out of drain holes when I pump the bulb.

[boscoe99]

Have you tried not advancing the throttle to a fast idle? You are adding more air at a time when there is already too much air.

[panasonic]

My 1998 Yamaha 25 hp 2 cylinder 2 stroke outboard is hard to start after sitting for a few days. I pump the primer bulb witch is usually hard, pull the manual choke out and set the fast idle lever for hi idle. It will take quite a few cranks before it will fire. If I spray a little gas directly into the carburetor it will start right up. Once it fires it will it will fire immediately for the rest of the day. Pumping the primer bulb does move gas thru the gas filter to the fuel pump. I'm guessing It's the fuel pump but the engine runs fine at all rpm's and has plenty of power. it's just a problem after sitting for a few days.

I have a 1989 20 hp two stroke which is essentially the same as yours. I too can hear the fuel going through fuel system to the carbs. I pump it up until it will not push anymore fuel, full manual choke, handle to start position and three pulls and it starts everytime.
I am wondering if your choke plates are closing all the way?
After mine is started for the first time it doesn't need to be choked anymore for the rest of the day..in the summer. In the winter I may have to use the choke again if it is shut down for a while.

[fisherman363]

Thanks boscoe99 - panasonic and 99yam40-- I'll try these suggestions tomorrow if the rain lets up.

[fisherman363]

Finally stopped raining this morning - First thing I did was remove the carburetor bowl drain plug. Gas drained out and when I pumped the primer bulb gas flowed out as I pumped. So I'm assuming the problem is not gas to the carburetor. But I always pull the choke out all the way when starting the engine cold. I pushed the choke in and the engine fired right off. Could it be that my problem is using the choke to much? I'll try it tomorrow morning with no choke and see what happens. Any thoughts?

[boscoe99]

Many many many different motors of the same type,design and construction cab be a bit fiddly. You just have to experiment to find what works the best for you.


Mechanically fuel injected air plane motors have humbled many a pilot when trying to restart a hot motor.

[DennisG01]

You'd think that a carb is a carb is a carb... but, nope. It's almost like they all have their own way they like to be started. Outside temp factors in, too. Sometimes full choke - sometimes partial - the more you use it, the better you'll get at figuring out your finicky little friend.

As an example, I've got an old Merc 9.8 that typically like one pull with full choke, then about half choke for the second pull and it will fire right off. Well... that's the way it DID like to be started, anyways... found the boat sunk at the dock at the end of last season. We'll see how it likes to be started after I finish tearing it down and rebuilding

[fisherman363]

OK Dennis- I tried half choke and half lift of the fast idle adj lever and it seems to start much better. I'll continue to experiment and report back.

[zenoahphobic]

Have you tried not advancing the throttle to a fast idle? You are adding more air at a time when there is already too much air.

True.
But often a too far opened throttle actually sucks more fuel than wanted (higher fuel to air ratio) as just spluttering liquid drops rather than fully atomised: the inherent problem with carburettors run at very slow motor revolutions.