Engine/Transmission (1998.5 - 2002) Lift Pump Help

[Souders]

My lift pump pressure was starting to be erratic monitoring with an installed gauge. Installed a new pump. Now when key turned on without starting engine no longer do I see the pressure on the gauge checking input and output of filter using two sensors. Starting engine I get normal pressure after a few seconds. This pump seems to be extremely quiet, I can not hear it run when key turned on before starting. Installed P/N 3990105 on my 99 24v.



Any input appreciated.

 

[RAJohnson]

When I was still running my stock LP all I would see on my fuel pressure gauge was a slight bump in the needle when I turned the key to the on position, I think due to the power coming on. I would also hear a click under the hood if I turned every thing off and open the door to listen real close, I always figured it was the pump being energized before starting. I would then see pressure after one or two seconds of starting it up. I have a electrical fuel pressure gauge (just so you know) and I replaced my stock LP with the FASS system just a couple of months ago because my LP was only delivering about 4psi @ WOT.

 

[Souders]

LIft pump

Thanks for the input. Drove truck today and pump seems to be acting normal. See proper pressure before stating.

 

[Bob Wagner]

there may have been air in the lines too.

 

[Fishin Guide]

Mine did the same thing. Remember, the factory overflow valve has a bleed orifice in it. I assume this is to aid pushing air out of the system after a fuel filter change. This is why the pressure drops so quickly after shutdown.



I would not worry about it as long as you have good pressures at idele and under WOT.



I now have both. :-laf



Dave