Rough idle and fuel primer bulb

[hertel11]

I have a 9.9hp Johnson that idles very rough and will not start even after being warm without at leas one third throttle. It runs smooth while giving it gas but the idle is very rough. I've noticed also that the fuel primer bulb is always collapsed after running the motor and is even hard to hand pump full. Are these two issues related or separate and will either cause damage? I replaced the bulb and lines from tank to engine with same problems. What should I do?

 

[alldodge]

I have a 9.9hp Johnson that idles very rough and will not start even after being warm without at leas one third throttle. It runs smooth while giving it gas but the idle is very rough. I've noticed also that the fuel primer bulb is always collapsed after running the motor and is even hard to hand pump full. Are these two issues related or separate and will either cause damage? I replaced the bulb and lines from tank to engine with same problems. What should I do?

I would check the vent on you tank, it's probably clogged and your drawing a vacuum

 

[hertel11]

Vent checked and free of obstruction. Running with cap open doesn't change anything either. Inline fuel filter and filter on pickup tubing free of obstruction as well. My only other idea is that the elbow coming from tank to fuel line is clogged inside it or something..?

 

[alldodge]

Vent checked and free of obstruction. Running with cap open doesn't change anything either. Inline fuel filter and filter on pickup tubing free of obstruction as well. My only other idea is that the elbow coming from tank to fuel line is clogged inside it or something..?

It it is also an anti siphon valve, and that would also do it, there would be a check valve in it

But do keep in mind, I'm not an outboard guy, just commenting hoping others would see and maybe other comments would come

 

[GA_Boater]

I take it you have a portable tank.

Sometimes the fuel pickup screen gets plugged with stuff which could cause the collapsed bulb.

Take your old hose and bulb and cut the tank fitting off. Dunk the hose end in the tank filler to bypass the pickup/anti-siphon and see if the motor runs better.

 

[airshot]

Ran into that same scenario last season on my 9.9 evinrude. As it turned out on mine the connector that plugs onto the tank was sucking air. I ended up connecting the fuel line directly to the tank without a removable connector and problem solved. On my setup I have a long fuel hose run of 12' so any tiny bit of air slowed fuel delivery. Can't say it is your problem or not but someplace to look.

 

[Silvertip]

Sucking air would not collapse the primer bulb. The restriction is between the bulb and the bottom of the dip tube in the tank. If this is a plastic tank, drain it and check inside carefully for bits of plastic debris. That stuff can clog up a dip tube and even rupture the screen. I've checked brand new tanks at many stores and a good number of them have debris in them from the drilling and manufacturing process.

 

[MH Hawker]

i ran into one of the silver foil seals from a additive bottle being sucked into the tank fuel pick up several years ago, like to drove me nuts

 

[hertel11]

Ok. I will try to clean/drain the tank before anything else I suppose because debris and/or additive foil seem likely. It is a built in tank that is pretty hard to get access to so I guess that will be fun... Will have to remove battery, oil tank and some other hoses just to get to it and then to get it out will be another project in and of itself. I'm not sure the best way to go about it.