Fuel Pressure

[Tahoehybrid18]

So I have a question. How reliable are the fuel pressure readings from a OBD scan tool? I'm trying to track a issue, and during that tracking I noticed that at startup my fuel pressure is 59 psi, then after getting a block down the road, it drops to 47, and I've seen it as low as 43. Also recently I'm getting a slight rotten egg smell from the exhaust. Usually a longer drive and its gone, but its weird.

 

[swathdiver]

So I have a question. How reliable are the fuel pressure readings from a OBD scan tool? I'm trying to track a issue, and during that tracking I noticed that at startup my fuel pressure is 59 psi, then after getting a block down the road, it drops to 47, and I've seen it as low as 43. Also recently I'm getting a slight rotten egg smell from the exhaust. Usually a longer drive and its gone, but its weird.

Well, those are the readings that the engine's computer is seeing. Now, to test the accuracy, there is another line called "commanded fuel pressure", what the computer wants the pressure to be at and then actual fuel pressure. There are also fuel pump short and long term trims.

Energizing the rail at 58 psi is about right and running at 43/43.5 psi is normal for a Gen IV 5.3 motor.

 

[Tahoehybrid18]

It's a 6.0 dont know if that's a difference, I had just read somewhere that it shouldn't be less then 60

 

[kbuskill]

Flexfuel engines run 43.5psi while running... not sure about others.

 

[swathdiver]

It's a 6.0 dont know if that's a difference, I had just read somewhere that it shouldn't be less then 60

No, it's 50-60 psi when you turn the key on but the motor is off. It should not drop more than 5 psi in one minute either.