With the 3 blinking lights, you can get the second level fault code and this will tell you a more extact reason.
To see the other fault code, when the generator quits and you see the three blinking lights, push down on the generator start/stop button for about a second (either the button on the generator or on your dash) and another series of blinking lights will occur. Count the blinks. For an error code of 27, there will be two blinks, a pause, and then seven blinks. The blink cycle will continue for about 5 minutes. If you still have your manual, the fault codes will be listed. It could be any number of reasons for the shutdown and the manual has instructions to correct the problem for some of the faults.
Also, you can get the second level code without causing the generator to fail again. The last fault code is stored in the generator's 'memory'. Just push down on the generator button and the blick cycle will start.