Hello,

I have a 2006 LR3 4.4 with 110 K and I need some expert advice.

I have had lean codes (P0170 and P0174) for a while now, they don't seem to affect the function of my truck but I have spent a great deal of time chasing them down. I have tested or replaced most of the intake for leaks, replaced the PCV valve, intake manifold gaskets, hoses (the truck overheated before I got it and needed it). rebuilt the heads, ran cleaner through the system both rail and tank. Inspected, replace injectors and o-rings and replaced the MAF. And flashed the ECU to remove the old programming.

I previously tested the fuel pump, and got 65 psi and disconnected it. Today I decided to dig deeper. What I noticed is after sitting overnight, there is zero pressure in the system. I can disconnect the lines and no gas spills out. Previously I drained the pressure first. Second, when I first start the engine, it holds dead on at 65 psi with little movement. This is when I disconnected it before. But this time I let it run a while, after a few minutes the needle begins the jump, basically down. It never levels out at 65 psi as it becomes a blur. From my observations, it appears to reach as low as 50 psi while idling.

I think I may have a bad fuel pressure regulator. From what I understand, that is part of the fuel pump. Or does this tend to happen on these and I should just get the ECU reprogrammed?

Thanks,

Ovide

 

This info might help you out

"FUEL PUMP- the submersible electric fuel pump is attached to a carrier and is located at the bottom of the swirl pot inside the fuel tank. The fuel pressure regulator, which controls the fuel pressure in the feed pipe to fuel rail, is located in the fuel manifold in the fuel tank.

FUEL PRESSURE ACCUMULATOR- A fuel pressure accumulator is attached centrally to each of the fuel rails. The accumulators act to dampen pulses from the pump and ensure that the fuel pressure in the rails is constant"

 

Thanks for the reply. Is the fuel pressure accumulator a tuned port vessel? If yes, would it work and then fail? I just dont know how to explain the pressure holding at 85 and then start bouncing.