'08 5.3 - Fuel Pressure at fuel rail

Mossyoakglock · June 27, 2016

Should I have fuel pressure at the rail after the truck sits overnight after 10+ hours? This is with the truck completely off, not even KO/EO.

I'm chasing what I believe is a fuel pressure issue and went to check the truck one morning and I had no fuel pressure at the rail after the truck sat overnight. This is with the truck completely off. I had to depressurize the fuel system to change out a sensor and when I went to press the schrader valve to release pressure, nothing came out. There was no pressure what so ever.

Just to test things I pressed the valve after the truck had sat for only 2-3 hours and I still have full pressure and ~60 PSI Key On/Engine Off.

Should I have pressure at the fuel rail after the truck sits over night or is pressure supposed to bleed off completely and then once the pump is primed, have the full 60 psi with key no/engine off?

rjgti · June 27, 2016

it should remain pressurized

Mossyoakglock · June 28, 2016

So I guess that's why I get the stumble/slight miss at first start-up. The fuel pressure is bleeding off overnight and there is no pressure in the fuel system.

I'm guessing that the pump can't fully pressurize the fuel rail since it bleeds off completely overnight and there is not enough fuel for the first few seconds until it builds full pressure and causes the stumble. There must be a check valve going bad on the pump because once it starts, it runs fine.

rjgti · June 29, 2016

yuppers

Mossyoakglock · June 29, 2016

And just for my sanity. If it was a leaking injector, it would take 2 or 3 cranks to start (meaning try to start, turn truck off, try to start again, etc) or my plugs would be wet, correct?

I wanted to pull my fuel rail but not sure if there is enough slack on the line to be able to lift the entire rail. It's much easier to pull my plugs to see if they are wet.

I also don't have any fuel smell outside the truck or under the hood which keeps me pointing to the pump that is bad.