I have a husqvarna 55. I put in a new carb, coil,

Did you have the problem before replacing the filter and lines? You may have a fuel blockage inside the tank. Make sure you have a good gas flow to the carb. Dirt or other material may be in the causing the carb float to let too much fuel in. A bad air filter will cause the carb to run rich. Possible a bad spark plug or the spark is weak to the plug.

I'm sorry to hear that your Husqvarna 125B blower isn't starting. Here are a few things you can try to troubleshoot the issue:

1. Check the fuel level in the tank. If the tank is empty, fill it with the correct fuel mixture (50:1 ratio of gasoline to oil). If the fuel is stale (more than 30 days old), drain the tank and refill it with fresh fuel.
2. Check the spark plug. Make sure the spark plug is clean and properly gapped. If the spark plug is dirty or damaged, replace it.
3. Check the air filter. A dirty air filter can restrict the flow of air, causing the engine to run poorly or not start at all. Clean or replace the air filter as needed.
4. Check the carburetor. If the carburetor is dirty or clogged, it can prevent the engine from starting. Clean the carburetor or have a professional service it.
5. Check the ignition system. If the ignition system is not functioning properly, the engine may not start. Check the ignition coil, ignition switch, and any other related components to make sure they are working correctly.

If you have tried these steps and the engine still won't start, it may be necessary to take the blower to a professional for further diagnosis and repair.

Your carb seems to be flooding. You might want to adjust the carb inflow line.

Check flywheel key again, I've seen ones that were partially sheared, would not start. New key and they start right up

Here's a quote from amy Chilton's manual for 1980-1987.

"Several types of fuel filters are used. One is located in the fuel tank of all the vehicles and is part of the fuel guage assembly. Second is a sealed paper element, in-line unit; mechanical system- located on the engine (above the fuel pump) or electrical system- located in front of the fuel tank. Third is a paper element, in-line fuel filter/vapor separator, housed in a fuel resevoir. Normally, the in-tank filter does not require changing. If it does, the fuel tank must be removed. "
This thing you describe sounds like the typical Chrysler in-line filter of its day. It is nothing more than the same generic in-line plastic see-thru filter you buy for your lawn mower except in the 70's and 80's it was covered in metal and had a Chrysler part number. A lot of guys added an extra filter in those days, it wasn't the best system. I would remove the outlet line and turn the fuel pump on, see if you get fuel. Replace if needed.

Adjust the carb.,or rebuild it.

this new gas is a carb killer you will need a new diaphragm for the carb and there is a little screan next to the needle and seat that can be cleaned. about a 5.00 repair if done right.. use marine gas

hi
if you have a good compression,a strong enough blue spark and carburetion for the fuel air mixture try priming the engine(put small amount of gas in the spark plug hole)then start the engine.If the engine runs only the gas you put inside the cilinder there is a carburetion problem to find and fix.
let me know regards savumihai71

I think your on the right track
Blowing compressed air through your tank vent
is great but it is way more air than the natural asperation
that the saw pulls on it own
I would replace the vent cap and also look for a pinched fuel line between the fuel tank and the carb

Probably needs a carb kit, check main jet and main fuel inlet jet, is the spark crisp, fat and powerful, try running it with a borrowed coil as this may have an intermittent fault. Is fuel cap breather working or blocked, these small carbs are very sensitive. Make sure all is well with gaskets and diagrahms. Good luck the Yeti