I have a 2004 mustang GT with a Kenne Bell supercharger and several other mods including a boot a pump. The car has about 40k mi and has been well taken care of. I suddenly have a problem with excessive fuel pressure. The fuel pressure increases with engine temp. Normally runs 32 psi and increases to about 45 under boost. Suddenly after about 5-10 min of normal driving the fuel pressure increases to 48-60 woth no boost and has gone as high as 75 psi under 9psi of boost. After the car cools the fuel pressure drops back down to 32 psi. I have checked the boost a pump and it is working normally with all the correct voltages on the output side 12v no boost and 17v under boost.

Leaning toward the fuel rail pressure transducer (sensor) or the fuel pump driver module FPDM

Anyone ever have an idea on excessive fuel pressure?

 

I would also look first at the fule pressure regulator/sensor.

 

Just an update. The fuel pressure sensor did not fix the problem. I am doing some more testing and will reply soon.

 

May be a partially plugged filter. Wouldn't hurt to change that anyway.