Issues with Yamaha 9.9 losing fuel pressure

[DollarBoat]

I have a Yamaha 9.9 (t9.9exhw) which is plumbed to my main tank. When running it, the ball to pump the gas goes flat and the motor dies. If I keep pumping the ball it runs fine and if I stop, it deflates. I noticed when I took the cover off the motor, gas was dripping out from the bottom of the carb. Could this be the problem?

 

[Brew]

Mine did the same thing when I ran my kicker line from the same filter as my main... I ran it its own filter and all was good.

 

[Sir Reel]

If the bulb deflates then sounds like it might not be able to suck enough gas through the hose. Connect an external tank to the motor and see if it runs ok.
I ran my Yamaha off the main Mercruiser fuel filter for 10 years with no problems. Might even be a bad bulb.

 

[Goathorns]

I have a Yamaha 9.9 (t9.9exhw) which is plumbed to my main tank. When running it, the ball to pump the gas goes flat and the motor dies. If I keep pumping the ball it runs fine and if I stop, it deflates. I noticed when I took the cover off the motor, gas was dripping out from the bottom of the carb. Could this be the problem?

Change the big gas filter, it is plugged!

 

[wolf]

One of the problems may be the fuel pump diaphragm on kicker
few things you need to ask first
1 whens the last time its been replaced
2 do you have an anti siphon on the kicker side of filter as your main will suck back and wreck the kicker diaphragm over time

sometimes its like chasing a ghost with the fuel systems good luck bud

wolf

 

[Sir Reel]

Change the big gas filter, it is plugged!

Ya might be as simple as that. The main has a bigger pump and can suck gas through the filter but the kicker can't. Filter should be changed every year in my opinion.

 

[DollarBoat]

Are you referring to the water/fuel separator filter? If so, I believe it was changed during winterization last winter but I'll check the records.

 

[Island Fish Lifter]

another thing to check is that your primer bulb is pointing in an upright direction so the check balls work properly. This is especially important if both your engines draw fuel through the same filter, and even more so if your main engine is an outboard and also has a primer bulb (which also needs yo be oriented properly).

 

[Bondo Bill]

I fought this same issue on my boat with 3 different Yamy kickers for years. Someone told me to remove the anti siphon valve from the outlet of the gas tank.
I was told that the kicker didn't create enough pressure on the ball in the anti siphon valve to open it.
I removed the valve 2 years ago and have not had the problem since.

Bill

 

[DollarBoat]

So what do you guys think about the fuel leaking from the bottom of the carb? Is this normal, ie. Overflow? Seems to me it shouldn't be leaking at anytime.

 

[bigdogeh]

you need to pinpoint where it's coming out of the carb. bad carb bowl gasket? maybe bolt at bottom of basket needs to be tightened to compress gasket further. might be loose. or is fuel coming out of an overflow hose? needle seat may have a piece of dirt in it causing needle not to seat correctly when carb bowl gets full and carb float rises putting pressure on needle to seat. if i have fuel issues on a small engine sometimes just removing the float bowl and spraying everything with a bit of carb cleaner helps. you would be suprised how much crap, varnish, etc, can still get in there sometimes. make sure you don't lose any small springs, retainers for needle, etc. lots of small parts in there that can be lost if you don't take your time.

 

[Bondo Bill]

So what do you guys think about the fuel leaking from the bottom of the carb? Is this normal, ie. Overflow? Seems to me it shouldn't be leaking at anytime.

Its not uncommon to have fuel dripping off the bottom of a carb and collecting in the lower cowling especially if the motor is tilted up or if the primer bulb was squeezed a few too many times.