Air in fuel line

[PLP]

With the help of fellow iboats members I have almost got all the kinks worked out on my boat.

The problem I have yet to solve is I am getting air in the fuel line.I have a new tank,new bulb,new connections at the tank end,and new clear in-line fuel filter.

The motor is a 98 nissan 30hp 2 stroke.When I pump the bulb I am seeing air bubbles in the filter,the clear filter stays half full of air.The motor still fades a hair on top end at WOT.Sometimes the fuel drops back into the tank as soon as I quit pumping the bulb...Everything seems tight,I can't understand it...Even with air in the system I pump the bulb real tight,and the air just won't seem to come out.I am opening up the valve on the tank cap.Also I have bought 2 different bulbs in case 1 was bad.I blew air in one end,and then the other.It allowed flow only 1 direction..But why would it be letting fuel drop back to the tank?The arrow is facing the right direction,and when pumping the bulb it will pump fuel all day long when I open the end fitting and shoot it back into the tank.

 

[Sea Rider]

Re: Air in fuel line

The problem I have yet to solve is I am getting air in the fuel line.I have a new tank,new bulb,new connections at the tank end,and new clear in-line fuel filter..

Check elbow tubbing at tank, the tube that picks gasoline to hose, check if there is a O'ring at base, if so, is it in opt condition, change if not, turn tubbing CW untill well seated at base, also check interior hose that goes from engine gas entrance to filter for cracks, porosity, O'ring filter cup if missing. What is the purpose to have a middle in line gas filter ? the stystem already has two, one at the bottom of elbow tubbing, the other at gas pump entrance, both performs fantastic, no need for a third one. Try testing removing middle in line filter and checking all above.

Happy Boating

 

[PLP]

Re: Air in fuel line

I removed filter from inside housing just before fuel pump that's why I have the new filter.Everything else checks out fine..Fuel pump seems to be leaking somewhere...would this cause some of the above mentioned problems?

I messed with it enough,and after alot of pumping got all the air out,but at WOT it still fades a bit,and then picks up again on its own.Just not fading as much as before you helped me fix the other issues...If I let off,and hit it again it runs harder,then fades out..then picks up again..If I pump the bulb it seems to make it run stronger 9 times out of 10..Sound like I need to change the fuel pump?Thanks searider.

 

[Sea Rider]

Re: Air in fuel line

Ok about in line filter, is the gas arrow flow correctly positioned ? Definitely a troubled pump won't give best wot performance, check gas pump diaphragms for craks, leaks, 2 flat check valves not closing properly or bent and pump gasket to engine body. Parts are cheap, no need to change complete pump as in mayor cases you will only need the internal transparent & black diaphragms and probably check valves, If other pump internal gaskets are ok, can still use them, are thick and well made and to my surprise won't break when removing.

Happy Boating

 

[PLP]

Re: Air in fuel line

Thanks again searider..I will do the checks.