St Francis had the better of the first 20 minutes but Selsey came into it and it was fairly even to half-time.
Rob Wimble had a half chance when his lob went over the bar and Bruno Montero could have done better with one chance at the far post.
A couple of tackles by the home side left a little to be desired and the Blues felt one by centre-half Aaron Walsh should have resulted in a penalty in the 43rd minute. But the referee deemed there to be no foul.
In the second half Selsey started brighter - but from one of their attacks, St Francis took the lead when the move broke down and they cleared the ball upfield.
With Ollie Haggar out of position Pears got away and played the ball into the box. Striker Pitcher and Selsey defender Marc Hinshelwood went for the cross and Hinshelwood appeared to knock the ball away for a corner.
However the man in black awarded a penalty to St Francis. To rub salt into the wound Walsh stepped up to fire past Sam Joyce in goal.
Selsey’s best chance of the half came when Calum Britton broke clear in the 83rd minute but he chose the wrong option when he shot wide instead of squaring to John Miller for a tap-in.
Selsey remained fourth from bottom - and, as reported elsewhere, also lost manager Richard Towers, who relinquished his post on the same day.
SELSEY: Joyce, Haggar, Hinshelwood (Broadbent), Hegarty, Lee, Dan Miller, John Miller, Wood, D Towers, Wimble (Woolf), Montero (Britton). Sub not used: Covill.
See the Observer - out now - for the latest on Selsey’s search for a new manager