Small Engines (Lawn Mowers, etc.): Craftsman 2 cycle engine, fuel tank cap, lean mixture

Question
Hello Ben
Sure could use your help.
Craftsman shrub edger, 18" 2-cycle engine. Model 23 cc/1.4cu. in. 2 cycle Model# 358.795750-18.
Unit runs full power as expected for about 5 minutes and quits. Then only way to restart is full choke to restart and will run less than a minute after turning choke off.
After it cools down for an half-hour, I can get it to run for 5 minutes.
I changed the fuel with fresh mix of 40:1.
I changed spark plug, fuel filter and air filter.

There are small air bubbles in the gas lines
There are 2 gas lines, 1 large and 1 small that goes into the gas tank and up to the gas chamber where the throttle body is located. Very simple design.
My unit is about 3 years old, but looking at new off the shelf units today, they are identical. The large line just has a tip protruding into the gas chamber, the other small line has the gas filter.

Any ideas what may be causing it to stop running?

Answer
Phil
Please check the following these may be some of the problems.

  1.  Fuel tank is empty or shutoff valve is closed, or fuel line or   fuel tank cap vent is clogged.
  2. Carburetor is overchoked.
  3. Carburetor is improperly adjusted or needs service.
  4.Is the gas cap venting OK?

next time unit quits,  remove plug wire and put a spare plug in , ground to block and see if you have spark.  ignition coil might be shorting out.It sounds like you have a fuel flow problem of some kind.  Perhaps the fuel
line has a leak in the tank and you are getting bubbles (causing a lean
mixture)