If 2008 and 2009 are the same---The pump is mounted to the underside of the floor under your feet when you are at the helm. You should be able to hear it there when you run the water. Take out the screws in the grill on the cabin heater that is fed by the heated engine water, and pull the heater assembly attached to the grill straight out. there should be enough hose and wire on the heater that you can set it to the side without disconnecting. The pump has two wires, probably no connector plug. If enough wire, you can get it out far enough to take pump apart. Here is the tricky part: the rear mounting screws are behind the pump, and not visible. They are the same as the two in front that you can see. Must be removed and replaced by braille. Not as bad as it sounds. A mirror may help. Also, a towel underneath to catch wayward parts, which will otherwise never be seen again. If not enough wire, or if replacing the pump, you will have to cut and splice the wires with marine crimp connectors. The hoses usually come off with a slide connector that holds the hose end into the pump body. slide away from the pump about 1/2", and the hose fitting and O-ring will come out.
If you are not sure of the problem and are not decided on replacing yet, you can disassemble the pump head and look for debris in the rubber-like check valves arranged in a circle. I cleaned mine very carefully with a pair of tweezers. All of them had plastic shavings in them. This made the checks leak back, allowing a pressure drop, and the pump cycled about every 3 to 5 seconds with no faucet open.
Although the pump manufacturer states there must be a filter on the supply side, there was none in mine. I added one I found on Amazon. Clear bowl and stainless screen. Spliced into the supply hose from the tank with barb fittings supplied and two hose clamps. Also could be a problem with the pressure switch, but that usually shows as no start on demand, or erratic operation. I would also check the check valve on the dockside water feed; mine had a slow leak back. I did all this through the opening for the heater. not too bad except for reaching the shore-water check valve.
Good luck. Hope my '09 experience applies to your '08.