Outdoor Power Equipment and Small Engines - Homelite string trimmer Questions

Fired the lawn service and broke out the old trimmer only to find the fuel lines and the primer bulb rotted away, replaced them and want to know which fuel line goes where. One line has a filter and one does not
I dis-assembled and cleaned the carb and it runs, but not quite correctly and is hard to start.
Cannot find a model number but it is around 10-12 years old and is red, there is two carb adjustment screws and I do not know which is idle and which is hi speed.
Can I get a schematic of that carb installation.
What is the fuel/oil ratio?

Bill

Fuel line with the fuel filter (pick-up) will go to the fuel pump side of the carburetor - generally on older Homelite's the upper most fitting from the tank. And the other (fuel return) runs from the metering side of the carb to the tank and this line will merely insert only about an inch into the tank whereas the pick-up line must be positioned on the bottom of the tank. As for the adjustments, start with each one at 1 1/4 turns out from seated, initially. A final adjustment will likely be necessary once the engine is up to operating temperature and will most likely be turned in (clockwise) just a tiny bit. Fuel/oil ratio will be 32:1 (4 ounces oil per gallon of gas), or, better yet, use a good synthetic oil mixed at the oil manufacturers recommended ratio.

Ok I had the fuel lines reversed and the return was all the way to the bottom of the tank too. The lines were reversed and the return is now about two inch into the tank.
Both needle valves were out a tad over two turns so I adjusted them to 1 1/2 and now it will not start. I sat it on the ground and after about 20 minutes there was a puddle of fuel on the ground coming from the carb throat. How can fuel run uphill all by itself, the tank is under the carb.

Bill

A high pressure area in the tank is ocurring naturally since the fuel tank is "sealed" from outgoing pressure and the inlet needle is being forced open by either a weak inlet needle spring or a worn diaphragm or, and since you now have the lines correct, the inlet needle is dirty/worn. In any of the above cases, you will need to recondition the carbuetor and I recommend installing the proper carb rebuild kit and a new intake gasket. What brand is the carburetor, Walbro or Zama? And, what are the ID numbers on the carb?

It's a Zama carb and I may have caused my own problem. When I took the top off to clean it I saw the lever with a spring that moves the needle valve and I noticed that the lever only pushed the needle valve closed. so I bent it up just a tint bit so if I pushed on it the valve would also open. I did not realize the tank became pressurized. I thought there was a breather in the filler cap like most tanks. I guess the pressure in the tank overcame the pressure from the spring.

This DIY site is the best. I have learned much over the years from here, just by reading the posts and responses. I am glad I finally joined up.

As a thought, after what I did, the first pull probably flooded the engine immediatly.

http://www.zamacarb.com/tips.html

The tech guide is kind of generic, not specific to any one model of Zama carb, but it's otherwise a very good resource for troubleshooting and tuning.

Thanks for the link for the service tips.

I still have an issue with fuel going up hill into the carb after I shut it off.
I turn the trimmer off and set it down and open the fuel cap to relieve the pressure and put the cap back on. Ten min. later there is a puddle of fuel on the floor and it is coming from the carb throat and the unit is impossible to start anymore.

When it runs, it runs perfect, smooth idle, quick throttle response, powerful, everything goes bad when I turn it off

My question now is about the return line to the tank that sticks only a few inches into the tank.

Is it supposed to stick in far enough to dip into the fuel or is it to be only into the air space above the fuel ??

can anyone answer this last question please

Check out the link to the Zama service tips page and you will find information on how to adjust the inlet needle lever properly. This is critical so you don't have fuel weepage at rest.

Thanks but once again, please just answer my question and please do not refer me to a manual or another site. I have done all that.

How far into the tank must the return line go? One half inch, One inch, two inch, three inch, etc. there has to be a measurment. Mine sticks about 1/3 of the way down into that tank.

Bill

It's a return line so it needs to be in far enough so it doesn't slip out when bumped 1" should be plenty. Have a good one. Geo

An inch is fine. As would be 5 or 10 just so long as you leave room for fuel.

The tool for adjusting Zama metering arms is Zama ZT1

With the unit being as old as you say, the best bet is that the needle valve that is attached to the lever and spring has hardened up on the tip and is not sealing properly. A good gasket and diaphram kit will contain a new needle valve. Taking you carb to a good shop you might find a kit in stock but due to so many different styles in use, most shop are ordering the kits for this carb. The numbers needed to get the correct kit are on the carb faces. Some chain saw shops might have the parts in stock. Note the lever spring keeps the needle valve closed and the diaphram opens the valve. The return hose lenght makes no difference on how much in in the tank just so the hose stays in the tank. The pick up hose, with filter, must be long enough to allow rotating the trimer to most positions and still be able to pick up fuel.