Some models the fore and aft bilges are not connected but I believe your model is. Do you see a tube at both ends along the keel line that goes under the fuel tank? If so try running an electricians fish tape through it to see if you can clear any blockage.
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2