What you need to remember is that the voltage at the pump should only be a few tenths of a volt less than BATTERY voltage and this will not be 12v while cranking. Battery voltage at cranking is acceptable to be as low as 9.6v, 10.5v is very acceptable.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician