4RnrRick

I installed a "BD-Power Auxiliary Lift Pump" from xtremediesel (part number #BD1050226). Anyways the Aux. pump is wired into a pessure switch plumbed to a oil galley in the block. That is so when the oil pressure on the motor reaches a pre-determined value, it activates the aux. pump.

Before the install my fuel presure was 11-12 psi at idle, 9-10 psi while cruzing and ~4-5 psi at WOT with the juice on the stock setting. With it on setting 1, I could get it to drop to 3 psi. lowest I seen it was 2 psi. After that I just left it on the stock setting until I got the aux. lift pump installed.

So after the install I'm seeing 24 psi at idle, 20-21 psi while cruzing and 14-15 psi at WOT with the juice set to 5x5.

But I've noticed on 'cold' startups my fuel pressure is only low (4-5 psi) when the engine first starts and sometimes even lower (2-3 psi) before the oil pressure comes up and it activates the Aux pump. Do you guys also have this problem? Is there anything I can do to stop this low fuel pressure on startup before it activates the Aux. pump?

country ...boy

I have the same setup and mine is always is lower until the oil press. comes up and turns on the BD but not that low 10-12psi is what I see from just the stock pump . Maybe yours is getting weak ? You could just by pass the press. switch and use a relay and have the stock pump activate relay. I have heard that to much press. on start up can cause a hard start but I dont know I've never had that problem.
Here are my psi numbers
10-12 start up
20-21 idle
17-18 crusin 60
5-7 wot 5x5 and sticks
Wish my wot psi was as good as yours ! LOL

scottsjeeprolet

I run mine triggered by relay off the stock LP.
25 idle, 20 wot.
Never had a hard start. After trying out a Smarty my LP only runs when i turn the key for about 3 seconds. The Smarty did something to help with the hard start problems seen in our trucks.

bigd450

Mine is identical to yours and I just put in a new injection pump and lift pump also. I believe it just takes a few seconds for the stock lift pump to start building pressure. Mine will some times start out at 0 for a split second then hang at 4-5 for another second then the bd kicks in and jumps to 23. At WOT with injectors it wont drop below 14psi.

4RnrRick

I also just changed my fuel filter - could I have a air pocket in the system?

I figure the stock Lift pump can't draw fuel through Aux pump when its turn off, so thats the reason for teh lower startup pressure. Does anyone have any ideal how bad the low start up pressure is on teh injection pump? I woudl assume since its just at startup and the engine is idling to get full oil pressure, its not as bad as low full pressure at WOT.

Or another idea I had was is there a way to keep the oil in those oil galleries, so your not starving for oil pressure right at start up?

So does anyone have any idea how hard its is

country ...boy

A way to prelube [build oil press.] would be awsome, with no dry starts these things would never wear out!!

erniew

The system on these trucks as designed to lower the pressure at start-up, the VP44 doesn't want any more than 7PSI to start. The ecm, duty cycles the supply pump to keep the pressure no more than 7 PSI for start up. That is why the BD comes with the oil pressure switch, aux. won't start until pressure is up

4RnrRick

But it seems like consistantly I'm starting it and my fuel pressure is 2-3 range. and now that I'm watching it I've seen it start at 0 psi a few times.... that can't be good!

But if I bump the key into the start without starting the motor, the fuel pressure will rise, and then when I start the motor I'm not starving it. I've only done that a couple times so I'm not sure what numbers I'm averaging doing that.