I have a Endress 7000BT 120V generator w/ Kohler engine. It will start wonderfully and run for about thirty seconds. I have cleared all gas lines, new fuel, cleaned carborator, have great spark, and have bypassed the off switch. It will run from 20 to 30second then die. If I try to put a load on it it dies. Any help would be greatly appreciated and thanks in advance!

Hi,
I would say it is still dirty (the carb) between the gas inlet and the inlet needle seat. Both symptoms you named a indicative of reduced fuel flow, both the run time and the dying under load.
Peace,
Clarke

When I fire up my generator, the engine runs fine. Checking the output,at first the needle jumps up to full wattage and slowly drops to no output,but the engine is still running fine.

Hi,
Bad brushes or dirty commutator.
Peace,
Clarke