I think something may be wrong with my intank fuel pump, but I'm not really sure. I have a 255 high pressure walbro intank pump. When I start my car up, it reads the normal 52 psi @idle, but after driving for awhile the fuel pressure starts to drop, and eventually goes down to 0 psi of pressure. As the fuel pressure goes down, I can notice the whining of the fuel pump getting louder and louder. Does anyone know what the problem is?

 

your pump is dead from overheating, killing the brushes.

intank pumps are cooled by fuel, since the pump is submerged. running low on gas will cause the pump to no longer be submerged in fuel, causing it to run hotter than spec, destroying the brushes in the motor.

 

i never run low on gas though

 

Yeah mine used to make a higher-pitched sound; now I've noticed that the pitch of the pump is lower now... maybe that's why I can't get above 7psi of boost w/out detonating...