Homelite 23A S/N 291242
When we started on this 1951 Homelite 23A generator, it would start , run for 10 seconds and then quit. I got a cup of rust out of the gas tank, cleaned out and replaced the fuel filter, replaced the primer check valve, replaced the rubber parts of the primer plunger ( that now works) and still the engine would start, run for 10 seconds and die. The fuel reservoir in the carb would run out of gas. The only thing that I had not cleaned was the J tube leading to the filtered fuel reservoir in the gas tank because there was no way to take it apart. So I cut it in two and found it packed with rust especially in the J section. See JtubeFix1.jpg.
I needed to know where the upper part of the tube went to clean it and understand how this thing works. Starting with a piece of wire, the J tube went to a drilled port I labeled A. This led to another drilled port B , and that to C and finally to D. I drilled the plug out of C and passed shop air thru the circuit, blowing out some more rust.
I noticed that the hole at D was not plugged. I assumed that it did not need to be since it would be sealed by the gasket. Wrong. On closer look, the port continued into the casting for the intake / governor. It is good that the gasket is glued to the governor side because if it were installed upside down. it would block the passage. I assume that the port leads to the crankcase, maybe thru a check valve. In the picture Crankcase Air.jpg, I inserted a tooth pick into the passage to make it more visible.
The way I think this works is that when the piston comes down, it compresses the air in the crank case, which is routed to the J tube. The blast of air coming out of the bottom end of the J tube propels some gas up the large tube and into the fuel reservoir in the carb. The hole in the bottom of the carb fuel reservoir is ported to the fuel nozzle / needle and drawn into the throat of the venture. Any excess fuel spills over the overflow tube and back to the tank.
With this fix, the engine runs and the lamp on top lights up.
I am planning on putting together a PDF to make a record of what I learned on this project and include some information from a manual.