Weed Eater XR-88 wont run

[giuseppe105]

Hello

I have an XR-88 weed eater and its not running. I changed the fuel line. it only had 1. and there is no primer. How does ait get back into the tank because its only sucking gas out causing negative pressure.

Can someone enlighten me on how this fuel system works.

thank you.

 

[Lawnranger]

Hello

I have an XR-88 weed eater and its not running. I changed the fuel line. it only had 1. and there is no primer. How does ait get back into the tank because its only sucking gas out causing negative pressure.

Can someone enlighten me on how this fuel system works.

thank you.

Some chain saws such as the Stihl MS 250 that I own have the same system - only one fuel line and no purge bulb. The carburetor has a pump diaphragm in it and is operated by crankcase vacuum/pressure via an impulse line or internal passageway in the carburetor. As the piston cycles up and down the pressure in the crankcase changes and causes the diaphragm to move up and down and draw fuel up the fuel supply line to the carburetor. As fuel is consumed by the engine air must displace the fuel in the tank or a vacuum would build and prevent fuel flow. Usually the fuel tank cap has some type of vent engineered into it and will allow a small amount of air to enter the fuel tank to displace the fuel as it is used.

On most Echo brand products they have a third line to the fuel tank dedicated for venting purposes. Most purge bulb equipped machines have two lines but they are also sealed systems and thus need an air inlet built into the tank system at some point, usually in the cap itself. I suppose it's possible that a small amount of air could be pulled in around the fuel line where is passes through the hole in the fuel tank but not all systems use a drilled hole in the fuel tank for the supply line to pass through. On some Stihl trimmers there is a removable adapter with two nipples for the fuel lines to attach so the manufacturer must design a way for air to enter the fuel tank without fuel leaking externally.

 

[giuseppe105]

K so i found out why it wouldn't start. It was because I replaced half the fuel line and it was leaking at an attachment so the gas wasn't making it to the carb.

Now gas is leaking out of the air holes in the gas cap.

Does anyone know how to adjust the carb.

It wont even sputter like its trying to start if i leave it at half choke or full choke.
It sputters and then stalls when the choke is open all the way. and It do-sent matter if I hold the throttle of leave it closed.