i can push the primer 100 times and when i take spark plug out i see no sign of fuel....is this normal?
YES
The problem with the primer bulb carbs is there is check valves inside to make them work properly. If those check valves stick open it won't prime, and most of the time it won't start. If they stick shut you don't get any fuel into the engine.
Check valves?? In a 20cc engine carb?
Wuuuuut?
but yes i can prime 50 times and fuel just goes into bulb and excess back into tank
exactly what it's supposed to do....
OK so you have an air purge bulb. IT removes air from the system. It does not prime the engine. If it did then you would flood the engine every time you pushed the bulb.
Finally someone says it...
How does fuel get into,combustion chamber then.....
BY PULLING AIR THROUGH THE CARBURETOR
Your lawn mower carb and edger carb work differently. The mower just has a primer bulb which shoots fuel into the carb throat. The edger has both a primer bulb and a choke. The primer bulb simply removes air from the fuel lines for an easier start. The choke is used to enrich the fuel mixture. You can start a 2 cycle without the primer bulb if you pull it a few times extra (fuel pump will purge air from the lines.) You can't start a 2 cycle without choke unless you give it a shot of starting fluid.
Not really. All small engine carburetors are remarkably similar.
All of them have a choke mechanism. On the cheaper lawn mowers, the choke is automatic because people who buy $150 lawn mowers can't be trusted to use a choke properly. On higher end and commercial mowers, there is a dedicated choke mechanism.
Additionally, you can start a small engine un-choked when it's cold, but it would take many pulls. Not worth it. The choke was invented to make starting MUCH easier.
I'm sorry, but this thread was such a mess to read.
I can't believe not once did anyone tell him the proper troubleshooting steps or even suggest using starting fluid. Wow.
Doesn't start?
Check ignition - on/off switch; check for spark at plug boot
Has spark?
Rule out fuel issues by artificially supplying the engine via starting fluid
Still won't run?
Check for any possible airflow obstructions - clogged/blocked air filter, intake, or possibly exhaust.
STILL won't run?
Likely blown compression. Remove spark plug and look into cylinder to check for scoring