Should be is the operative phrase. Isn't full is most likely from the sound of it since it will barely idle.

But Amervo has a point, you could fill the carb float bowl manually through the bowl vent like Vikki mentioned earlier to verify a fuel delivery problem. If it acts normal for the first ten seconds or so, then you definitely aren't getting enough fuel. Any chance you have the lines into and out of the mechanical pump hooked up wrong? The electric pump may have just enough pressure to overcome the mechanical pump but not enough to do more than idle.