2000 4.3l Fuel pressure Reg, P300
 

my daughters 2000 4.3 blazer has had an issue with the famous P300 random misfire. I have gone through a few things. cap rotor plugs, When I checked the plugs that have only about 2k miles on them, they were very carboned up. Other forums I have searched suggested the fuel pressure regulator. I got up the nerve to tackle this, It took some time and skin off the knuckles, but I accomplished the task. Now when
I tried to start it, it was like a hard lock of the motor. Turns out the cylinders have filled with fuel, and yhu cant compress fuel. I took the plugs out, disconnected the coil, unpluged the fuelpump relay and cranked the motor, blowing fuel out theplug holes.My question is: what would cause the fuel to fill the cylinder. Did I leave something disconected? forget a plug or something?

RE: 2000 4.3l Fuel pressure Reg, P300
 

Bad FPR. If you have fuel flooding the cylinders, the FPR is definitely shot.