Lift pump and injection pump NEED HELP

[motormadness798]

hello guys as i stated in one of my other threads i recently purchased an 03 LB7 to match up with my 05 LLY , it had a raptor 150gph lift pump on it, and i have paper work showing the oem injection pump was replaced about a year and a half ago.... has truck running in my driveway flipped it over to hot tune and it was just at idle, truck stalled, turned key back on noticed i didnt hear the lift pump engage so i flipped switch back to stock, hit the primer under hood took a couple tries but it fired up. left in on stock tune just as pulling in my driveway it acted like it was running out of fuel then stalled, would not start back up, removed fuel filter filled in with fuel reinstalled it. It fired back up for a few seconds prob till filter was drained, I assume the worst Raptor pump burned out? any body heard of that before what would cause that or are they noted for that? and also assuming my stock injection pump is ruined aswell, any input ideas would be great thanks

[motormadness798]

update::! ok so trying to troubleshoot this this using common sense first, i turn key on lift pump does not engage i removed the fuel lines from the lift pump and stuck a coupler inbetween them (to by pass the non working lift pump) took the lift pump into the garage and hooked 12v power to it, nothing dead so yes the lift pump is shot... now moving on to stock injection pump, as i said i bypassed the lift pump hoping the stock injection pump (if working) would pull the fuel through the lines atleast enough to start and run. I dropped the fuel filter and topped it off and spun it back on, hit the primer a couple times .....truck fired and sat there at idle let it idle for about 60 seconds jumped it it reved it up a bit went back to idle then acted like it was running out of fuel again and stalled. at first i thought YES ok the stock injection pump is ok.... now the only thing i know for sure is the lift pump is shot, can anybody pitch in here with some input?

[LB72004]

usually the first trouble shooting step is to replace the fuel filter with a new one.

i am thinking that you may have air in the lines. this could have happened when you where removing the LP or it may have a leak on the fuel line that may have been masked by the LP and when it died the CP3 was now pulling a vacuum and sucking air into the fuel lines. if there is no leak then you may just need to work the air out. don't keep removing the filter but keep priming the fuel lines and restarting the truck, you may need to press the throttle to keep the engine from dying. do this until it starts to run normally. then take it for a spin around the block to see if it is alright.

if there is a air leak on the fuel line then this would need to be repaired first before it will run smoothly. pressurize the tank to about 5 psi (air hose and rag or special cap with air connection) and inspect for leaks. suspect areas: primer bulb, bleed screw, water-in-filter sensor plastic parts at bottom of filter, rubber lines to and from filter housing and CP3. there can be other areas but that's the common spots.

there is also a chance that the FPRV was tuned for the higher pressure of the LP and now that the LP is out it is cutting too much pressure and stalling the engine. if the LP was wired to run while the engine was idling then it is likely that the engine would lope unless the FPRV was rescaled for the new incoming pressure. a new LP should fix this or putting the stock values back in the tune. something to consider.

[motormadness798]

is it possiable that it could be the fuel pressure regulator and not the actual injection pump?

[LB72004]

is it possiable that it could be the fuel pressure regulator and not the actual injection pump?

it is possible. you could test it with ether EFI Live or a Tech 2 and command max PSI and see if the CP3 and regulator respond correctly.

[motormadness798]

well the truck is a "no start" right now but if i turn it over for a few seconds and grab my PPE HOT +2 Race hand held out of my lly it comes up desired fuel like 6,300psi , actual fuel 230psi i dont know if these readings would be accrate though with truck not running

[LB72004]

i think you need something like 3000+ psi before it will open the injectors. can you see the % or desired regulator current/mm3? if you can we can compare this to the stock values and see if anything has been changed.

can you hear the FPRV humming right after you turn off the ignition?

[motormadness798]

cant see that info but i do not hear any humming after i turn off the ignition

[LB72004]

i have always been able to hear a hum or "buzz" if you will for a second or two when my hood is open after turning off the ignition. may FPRV still made that sound even after i replaced it. i know it is not easy to get to and there is a ton of crap in the way but i think you need to check/replace your FPRV. it could be stuck/gotten something in it or it may have burned out. there is always the chance that the connector is loose, bad connection or there is a break in the wires.

do you know if the LP was wired to be on when idling? if any mods where done to the CP3 or maybe an LBZ regulator was used?

[motormadness798]

ok i gave up on trouble shooting i did replace the fuel filter, just bought a reman modified cp3 pump 42% over stock and a new lift pump, is the mod cp3 going to be alright with the Efi live tunes that are already set to the DSp5 switch? because i do not currently own the efi live software, planned on buying it but it will be a little longer because of this "minor setback"