Fuel Pump Line question

[scb2987]

Hey Guys,

had to cut one of my lines off my old broken fuel pump. When I did it I thought I had enough slack to make up the difference, turns out I was wrong.. so my question is, where does the line go that comes of what would be the top nipple of this pump



ive got one coming from the tank to pump, its good
one going from the pump to carb, its good
then one going from the pump to under the motor. Where does it go, how hard it is to replace, and what does it do?

thanks!

[scb2987]

lots of great info on this site, I was finally able to stumble across what I think it might be, an air pulse from the engine that powers the fuel pump itself?

[TheNewGuy]

Yep it's a pulse (vacuum) line. Very easy to replace.

[scb2987]

[QUOTE=TheNewGuy;921627]Yep it's a pulse (vacuum) line. Very easy to replace.[/QU

whats the best way to get to it where it hooks to engine? cana I reach it from underneath? or do I have to take a bunch of stuff apart?

[TheNewGuy]

What model cart do you have?

[scb2987]

1996 g14

I just put a brand new carburetor and brand new fuel pump on it, I re hooked up the pulse line and I'm still not getting any fuel to the carburetor. How do I know if its the pulse motor ? how much suction should I feel on that line when I hit the gas

[sho305]

The pulse line is a pulse, it goes in/out. It is pressure from the piston going up/down. If you turn the engine slow you might feel it go in/out, a vacuum gauge would show it.

You might need to prime the pump if its dry, they are not the best at lifting fuel. Yamaha manual says to fill the tank if you run it out, that way the fuel is above the pump and it will prime easily. You can blow a little air in the tank with the line off the carb until the gas comes out (it will flow through the pump if installed correctly) but be super careful you only let a tiny bit of pressure into the tank its not made for that and does not take much to work. Some just put hand over fill hole and bump it a couple times with air gun, again not much pressure.

The pulse pump is a diaphragm pump just like any other, it also has two one way valves to let fluid in and let it out. The other side of the diaphragm is not mechanically moved in and out the pulse does it instead. Bellows to start a fire would be a good example of a diaphragm pump but for air not fuel.