I am repairing a Homelite Backpacker II leaf blower. The blower has a Walbro WYC-6 carburetor. I rebuilt the carburetor and replaced the primer bulb, fuel lines and fuel filter. The blower then ran, but the throttle response was sluggish. The blower shut off unexpectedly when at idle, and was very hard to restart. After this occurred multiple times, I suspected that the mixture was too rich. So I got the blower running and removed the air filter. The throttle response improved. Unfortunately, the carb has no mixture screws, so I couldn't adjust it. About this time, the blower refused to start at all and blew fuel out of the air intake when I turned the engine over. I took off the muffler and replaced it because it was full of carbon, but the carburetor still would not perform.
I looked up the cost of a replacement carburetor. It was close to $50, much more than I wanted to pay. So I installed the Zama C1U-W18 carburetor from a Weed Eater FL20 string trimmer. The blower started and ran, but it still shuts off unexpectedly.
I am not sure if the Zama carburetor is working correctly. A new one is $13, should I get it?
Here are some facts that might be useful:
1. The blower will not run with its Walbro carburetor.
2. The blower runs with the Zama carburetor, but it still shuts off unexpectedly.
3. The replacement muffler is used, but it doesn't look clogged inside like the original.
4. I tried replacing the ignition coil (with another used one,) but it didn't make a difference.
5. When the blower won't start, it does have spark.
6. The timing is not incorrect.
7. I thought that the pulse signal from the engine (that operates the fuel pump) might be entering the carburetor throat and blowing the fuel out the air intake, but all of the intake gaskets are in good condition and are not torn.
In case you were wondering, the used muffler and ignition coil are from a Homelite Yard Broom handheld leaf blower with the same engine. I have most of the parts from this blower (excluding the carburetor,) and can use them as necessary.
I don't have an accurate compression tester, so I can't give you a psi rating. However, the compression will blow my thumb off the spark plug hole. The engine does run, so I don't think it's a compression issue. The engine's unexpected shutdowns are the problem.
