A buddy of mine is having an issue with his 2010 Mustang. One day, as he was backing out of his driveway, the car just stalled. He tried cranking and it just cranks with no start. He calls me up and I go verify that it has spark, but I don't hear the fuel pump priming. I check all fuses and relays related to the fuel pump and they all check out. I pull the fuel pump and test voltage at the connector to the fuel pump. I am getting 13ish volts to the fuel pump positive wire (yellow/white). I think "must be a fuel pump" and order/install a replacement. Even with the new no fuel pressure up to the engine, not even a peep from the pump. So, I double test the old and new pumps with direct power and they both spring to life. I then replace the FPDM, but once again, nothing. I try splicing into the (white/brown) fuel pump negative wire and jumping that to ground. The pump whirs to life and the car starts upon cranking.
SO, it seems the issue lies somewhere between the FPDM and the PCM. I am thinking maybe the fuel rail pressure sensor could be falsely reading too much fuel pressure, causing the PCM to not allow the pump to turn on? Does the FPDM break connection from the negative (white/brown) wire when it is told to turn off the pump? So far, we are $300 into this repair and getting pretty frustrated. Also, to splice into the wire, I had to remove a little bit of the shielding and unravel the wire one time around to get it spliced, am I good to solder/heatshrink this back and get the shielding as close as I can without causing issues with the PWM...? Thanks.
SO, it seems the issue lies somewhere between the FPDM and the PCM. I am thinking maybe the fuel rail pressure sensor could be falsely reading too much fuel pressure, causing the PCM to not allow the pump to turn on? Does the FPDM break connection from the negative (white/brown) wire when it is told to turn off the pump? So far, we are $300 into this repair and getting pretty frustrated. Also, to splice into the wire, I had to remove a little bit of the shielding and unravel the wire one time around to get it spliced, am I good to solder/heatshrink this back and get the shielding as close as I can without causing issues with the PWM...? Thanks.