ZAMA carb

[George Marsh]

Working on a 25 cc Weed Eater. It will run fine at 1/2 throttle and 1/2 choke. Running lean if I remove choke or increase speed. There appears to be places where adjustable jets were, even marked L & H, but they appear to be plugged off.

Took carb apart many times and blew it down. No improvement.

What does a person do? Don't have a gun.
George

 

[rrobert]

Some of those carbs are cheap($25) to buy new. A diaphram kit is about $12 which is a good idea to install if you are opening it up. The diaphram(fuel pump, round aluminum on it) should be dry on one side and wet on the other. If it is wet on both sides, it is no good.

I can't tell from that pic but I have cut notches in the adjustment screws and tried adjusting it. I can't tell if those are permanent or adjustable.

If it is more than 4 years old, I would cut losses and buy a new machine. The $100 one's from Walmart, Home Depot, Sears and Lowes are disposable. If you get 3 troublefree years out of them, you have done well.
 

[George Marsh]

Just trying to fix it for another person..my guess is the weed eater isn't worth $25.

No adjustments on what looks like jets.
 

[George Marsh]

Went on line and checked out ZAMA web sight. It says that it requires a special tool to adj the carb and they don't sell the tool.

Any idea where to find the special tool?
 

[rrobert]

Might sell the tool. I have seen some that are half moons and others that are splined 12+ points like a torx.

I just used a thin grinding disc on a dremel and cut a slot so I could adjust it with a flat screwdriver.

I couldn't get either carb to work so I scrapped the machine.

One thing you should check is the exhaust. Remove the muffler and see if it runs properly. There is a spark arrestor screen that will get clogged with carbon. Either remove it or clean it.
 

[rrobert]

Be careful with the yellow lever. I broke the last one I worked on and had to patch it back together.
 

[George Marsh]

Went to ebay and found the tool for $7.97 including shipping. Ordered one.
 

[joe csuti]

If this carb is built same/similar to most walbro carbs an easily/usually over looked item in carb is the 100 mesh screen filter pressed into a cavity in carb body(I don't remember if it's under pump diaphram or metering diaphram)if this screen gets dirty/gummed up it will make eng run lean or not at all without choke,if carb has screen you can clean by carefully removing same from carb body,soaking in carb cleaner then blow out from backside & reinstall or goto link below & type 38-8121 in search,screens are priced each,but only sold in 10 pack,also while there click on chainsaw & look at zama rebuild kits,see if any for your mod# carb.
zama

 

[rrobert]

Also, check the fuel line inside the gas tank. The fuel line and return line will look fine on the outside of the tank but be rotten/cracked inside the tank. Replace with line from a small engine shop. Don't mix the lines up.