Had engine rework,studs etc,drove it,all was fine 90 miles later start up was rough,some misfiring,then ok. next start up more problems more misfiring,so bad that I did not want to let it suffer to warm up. Noticed that fuel pump continues running with 'ignition on' . seem to remember that the fuel pump only used to run for a short time when ignition key is turned to 'on'. should mention that fuel filter is old ( should have been changed with re-work) and engine ran out of fuel after re-work. fuel gage malfunction. could it be just a clogged fuel filter ? what about the fuel pump running continuously ? one more thing,with ignition 'on'& fuel pump running there is an intermittent clicking noise ( relay ?) but not from fuse box. Thankful for any input.