Hi again, How sensitive is voltage for the fuel pump. 1993 S10 BLAZER, battery at 10.5 volts car will not start no fuel pressure, charge battery to 12.2 volts and it starts fine. Is this normal or bad fuel pump?

 

Not sure about our blazers..but a lot of ecms are picky about low voltage and won't send voltages needed to certain sensors if it's under 12 or so. I'm pretty sure the only thing between the battery and fuel pump(switch wise) is the oil pressure switch...which just needs any oil pressure above like 4 or so psi. Sorry that I can't really help much but thought I'd throw something out there!

 

have your battery and alternator checked - make sure battery terminal ends are clean and tight - if I remember right a fully charged battery should read 13.5 to 14.5 volts - at 10.5 you are spliting minimal voltage through out the system with the starter taking most of it, add too that the ing. system and anything else that draws power it's not leaving enough voltage for the pump to power up