Diagnosing What's Wrong with Your Weed Eater Diagnosing What's Wrong with Your Weed Eater By: If the problem is too much fuel, syphon out some. If the problem is overcranking, you'll need to let the eater sit for about 15 minutes so that the fuel can settle. Next, check to make sure the fuel filter isn't clogged. This could prevent the fuel from reaching the carburetor. How to Tell if the Fuel Filter is Clogged on a Weed The fuel filter on a weed trimmer sits inside the fuel tank, connected to the main fuel line. It blocks any dirt or debris that may have entered the tank during refueling stops in the field. This filter needs to be replaced on a regular basis, about every 40 hours of operation, and every time you replace the fuel lines.