ORIGINAL: Sport_Pilot
Sounds like either you need a new plug. Glow plugs often give out during break in and bench running. Or a hotter plug. It could also be a rich mixture, but I am guessing you know to peak it out and give it about 3 clicks rich, or better 300 RPM rich using a tach. With the long run I would expect small bubbles before the fuel gets to the engine. Its from a small amount of fuel flashing from a drop of pressure and nucleation. As long as they are small enough that they don't cause the engine to surge or quit, then don't worry about the bubbles.</p>
I tried 4 glow plugs 3 of them being new ones of different brands. No dice. Bought a VP-30 fuel pump today, and I'll grab some more glow plugs tomorrow. The bubbles I was getting would join into bigger bubbles causing the engine to hiccup a little bit. The fuel line going to the carburetor was touching the outside of the cylinder so I moved it away. Problem solved.
ORIGINAL: DarZeelon
ORIGINAL: 1QwkSport2.5r
...It ran with glow-driver disconnected just fine on the stand and never flooded.
The 'automatic' answer here is that the low-end mixture setting you are running now, is too rich...
The setting on the test stand should have been richer than you now have, with the tank 6'' lower...
So, the engine should now be running leaner than it did on the stand.
Putting the glow-driver to work could keep the engine running in a rich setting, but it would conk out just the same, if it set too lean.
So, I can only conclude that you richened the low-end mixture, or that you are running a muffler that gives you a higher fuel-pressure, than you did during the break-in.
The other possibility is that your glow-plug 'went south'...
The tank setup was nearly the same on the test stand as it is now. 6" below and 2" back from the carb on the stand and 6" below and 3" back from the carb now. The engine ran better when it was 6" below and 5" back.
The Jettstream muffler's pressure fitting has a much smaller hole than most of my other engines, but it does provide plenty of pressure to the tank. I've concluded the problem is an overly rich idle mixture to promote fuel draw is drowning the glow plug. I talked to my local engine guy and he confirmed my suspicions. I bought a Perry VP-30 regulated fuel pump to overcome the issue. I didnt want to buy a pump because so many people said it should draw fuel fine and I was being a cheapass. I rescinded my cheapness and bought the pump. I'll test the pumped engine in the yard before going to the lake to verify its operation. I will vent my fuel tank to atmosphere running a tube up onto the engine stand so any splashing of fuel wont soak my fuel tank compartment.
This should fix the problem. I'll post my results after a Test run.