This vehicle is a 1993 ford f-150 with a 4.9 straight 6. The truck has been sitting for about three years. replaced both fuel pumps and starter relay soleniod. truck ran well at first the started to experinceing driveability issues. diagnostic reveals low system voltage of 8.9 v in fuel pump system and starter signal vehicle will start if you use a 12v to the starter solenoid. And will run just not well, has anybody seen this before please help thank you.