fuel flow question

[jcarey]

2005 9.9 Yamaha 4 stroke:question When I pump fuel line bulb it goes firm and stays firm. But it seems that not much gas is getting to the carb.I know the fuel flows Ok up to the fuel pump but have not checked it after yet. If I disconnect the fuel line from the pump to the carb not much fuel is evident and hold the line in an uprite mode the motor will start.Its as if whatever fuel is in the line from the pump does not go into the float chamber unless I raise the disconnected fuel line. If I place it back on the fuel pump it will not start and it is as if the pump is not pushing fuel to the carb.

My question is does the bulb pressure only put fuel to the pump and then the pump finishes putting the fuel into the carb until the float closes or should the fuel flow all the way into the float chamber through the pump just by the fuel line bulb?

Thanks

John

 

[yamamarinetech40]

Re: fuel flow question

I don't understand if you have a running problem or are just wondering how it works....is the engine running ok?
The Primer Bulb is just that....a way to prime the fuel line so the pump won't have to pull fuel all the way to it(with starter doing the work)....if you are having a problem just tell us what the problem is, and we can tell you how to go about fixing it....

 

[jcarey]

Re: fuel flow question

Yes, I have a problem. The engine will not start when cold unless I restrict the air flow of the carb. I am actually choking it with my thumb over the air intake of the carb. At first I thought the automatic choke selanoid was not working and I replaced it and still no cold start. Once I get it started and it warms up it will start ok for a time while it is somewhat warm then no start again. The carb has been cleaned three or 4 times and the fuel line and bulb has been replaced. It will start cold if I remove the fuel line from the fuel pump to the carb after cranking the engine for a few seconds and hold the end up in the air and it appears to drain what fuel is in the line into the carb and then the engine will start. It is as if the fuel pump is not pumping gas into the carb. I know the float and neddle valve are working Ok or it would not start when I raise the end of the fuel line and gas gets into the carb. I thought that the fuel line bulb would fill the float bowl of the carb and the fuel pumb just keep it full as the motor runs.
Thanks for any comments on this issue.

John

 

[yamamarinetech40]

Re: fuel flow question

You can pump fuel into the carb until the needle(mounted on float) seats itself when the float reaches it's proper level....if the needle is 'stuck', no gas can enter carb....but you say they've been cleaned...and you say the line has gas in it when you remove it from carb side of pump...but gas doesn't spray all over from the pump while you do this...the pump is bad if it's getting gas but not giving gas...if you take the line of the inlet of pump and pump bulb does it spray out? If so bad pump...

 

[jcarey]

Re: fuel flow question

Yamahamarinetec40

Thanks for the reply. Your answer is as I suspected but at $130.oo for a new pump I wanted to get another opinon. Thanks again for you help.

Jcarey

 

[BruceAML]

Re: fuel flow question

That fuel pump has repair parts available and there is no need to replace the entire pump. I would inspect the fuel pump diaphragm first and replace it if necessary.

 

[vx225mota]

Re: fuel flow question

If it is just the standard yamaha fuel pump as used on even the v4 and v6 outboards, then they only cost $35 from boats.net and lots of other places

I wouldn't rebuilt it isn't worth the hassle. They are plastic and can warp and still be junk after a rebuild. Mine were