You can disconnect the fuel line preferably on the top of the engine but the easyest place you can find Put the line into a plastic bottle turn the key to run to energize the pump and see what the out put is It should fill the bottle at least a thrid of the way up in about 5 secnods in general There is also pressure conciderations because the system dosen;t have any back pressure acting against it when the line is open But in general if it puts out a good amount of gas its probably good if not its deffinitly bad