Why do I have high fuel pressure...

[patrickt]

Originally Posted by steve meltzer

thanx. BTW, could a failed mechanical pump, ,plumbed the way mine is, cause a low pressure, even tho' the e-pump seems to be working OK? Am I making sense? s

Without it leaking, I'm going to say "No." Here's why: Think of your home's water pressure, which is usually around 80psi. So, if you put a pressure gauge on the end of your garden hose, with the hose not running, it will show 80psi. If you stab a really skinny, hollow swizzle stick in to the side of the hose, and put a gauge on the end of the swizzle stick, it will read 80psi as well. Obviously the flow out of the swizzle stick end would be much less than the flow out of the hose end, but the pressure will be identical throughout, provided there is no flow anywhere. When you turn your electric fuel pump on, and the car is not running, after a few seconds the pressure will be identical throughout the fuel system unless 1) there is a complete clog (in which case the pressure after the clog will be zero); or 2) there is a leak somewhere down the line that is reducing the pressure. In our swizzle stick example, a small crack in the swizzle stick will create a larger pressure drop at the end of the stick than the identical crack would cause in the hose itself, because of the volume of flow is much greater in the bigger hose. So, what this means is that if your electric fuel pump is really putting out, through its regulator, 6psi and the pressure on the far end of your fuel line run, at the fuel pressure gauge, reads 3psi, and the car is not running, then there must be a leak somewhere.