i have a 98 gmc [dont laugh] its dead again this time it in the fuel system im getting 12 volts at the relay and only getting 5.96 volts at the top of the fuel pump on the purpel wire is this right or should i be getting 12 volts i have 2 books on this junk and nether will tell it only says if you have curent replace pump were could i be loosing it . thanks