fluctuating fuel pressure from lift pump

[dj]

In my last post, I did not state my question correctly. What I really wanted to discuss is varying lift pump pressure when going down the highway. When cruising at 2000 rpm with a moderate load, the fuel pressure gauge will read 12 psi, but will not hold steady. At times, it will oscillate between 11psi and 13 psi, at times it will do this at idle, and at times the gauge will be steady. My gauge is mechanical, and installed on the injection pump body. Has anyone else experienced this, and what did you do to correct it? Will a additional pusher pump back by the fuel tank correct this condition?







2001 quad cab, 2500, 245hp, 6spd, aux. fuel tank, gauges,etc.

 

[SEmerson]

My lift pump started doing that be for it went out. It would bounce around and after awhile I just got less pressure. I looped it out and installed a mallery pusher. My lift pump is not used now. It is just riding around on the block for a backup.

 

[Ramafid]

I have a mechanical gauge also and it's doing the same thing. I'm pretty sure its caused by the heater grids cycling. It only does it when I first start up and once the grid turns off the guage is rock steady. I just hope the electrical drain isn't affecting lift pump life.

 

[pwr2tow]

dj,

move the sending unit from the injection pump back to the post filter side. I think what you are seeing is the pulses from the injection pump.

Ron