Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have a Stihl HS-45 trimmer that is a few years old. When I went to start it this spring it floods. It would start and run if you set the choke open and held the throttle wide open. It has a Zama carburetor that I have had apart. I can see nothing wrong in the carb and after putting it back together it ran as it should for a few minutes then went right back to flooding. My question is can you replace the carb with something other than the POS that came with it? From reading around it seems that Stihl has quite a problem with their carburetors. I have a blower and trimmer of the same brand but have not had any problems with them.

That carb is put on a number of diffrent things,  They are not really a bad carb...

If you have had the carb apart i can give you a little heads up on it.....

On the metering diaphram side of the carb,  there is a rubber tipped inlet needle pressed down by a forked lever /spring assembly.

The needle (same needle used on 98% of diaphram carbs on the market) ------ gets a bit of grit in its chamber sidewall sometimes.

If you take out the screw /spring/ forked lever that retains and works the needle , BUT IF the needle will not fall out of the chamber when the carb is turned upside-down (without tapping or pulling )--- the carb has grit in it now jamming the needle open...

If you have grit in the carb---- flush out the carb, needle chamber again,  Install a new fuel filter , and flush the line and tank..   Sometimes the needles wear a groove in the vitton / rubber tip and need to be replaced... (about 2 bucks for a needle, 3 bucks for a filter,   12 bucks for a needle / diphram gasket kit)

When you get the needle out you may notice that the needle tip has a anti-seize lube bonded to it  (silver in  color )...  if it is worn completely off in a ring pattern and the motor has about 50 hours or more on it,  just change the needle to save time..

Don't change / bend the forked lever installing the needle, if it is bent up the carb will run very rich,  if the lever is bent down the carb will starve...

I will post a picture of a tool used to check the leaking/ flooding of a needle when I get a chance...

Good Luck,

Friiy

Don't give up on that carb,  it 's a good carb

Okay, Here is an update. I have had the thing apart a couple of times and everything looks fine. I went by a local outdoor power equipment shop Saturday because the owner had called for me to fix a truck of his (I do paintless dent removal) and showed him the thing. He seemed to think the same thing as you about the carb not being a bad one. It's a Zama S70 so its the newer version with both H/L adjustments. He has a tech that he says can make it work right and wanted me to bring it in Monday on the trimmer. I went back home and put the thing back on and started it up. It ran the way it is supposed to so I added more fuel and took it out to use it. It ran fine the whole time I used it. Now I am perplexed about what to do. I would guess if it was something under or around the needle, its gone now. I did have the needle out a couple of times and no wear at all. It's probably not had 6 tanks of fuel ran through it since it was new.