LB7: ***help***
- Thread starter Vrabel
- Start date
well looks like I might be there as well. boss doesnt want to answer his phone so I guess theres no need to show up for work lol
Well, for starters abig thank you to Ben and Pete for spending the day out in the the cold. For those interested, it looks like my W/D FPR went bad. fuel's just by passing to return at pump.
How long had it been sitting? Mine failed, and Ive heard of several other failures after sitting.
I think it was a little over a month the motor was apart I think he took it apart the end of october
chris I was doing a little more research and one other thing it could be is the cascade overflow valve in the CP3...I need to double check if the fuel pressure regulator, when stuck at the extreme open position can dump enough to not let any rail pressure build......if thats the case (even when stuck at full open, it will still let the CP3 build 1500psi or so) then the regulator might still be good...and the CP3 itself could be bad, and in which case my regulator diagnosis would be incorrect. 
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ben
:ben
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what we checked is how much fuel the CP3 is returning. Even with the fuel pressure regulator unplugged (full rail pressure), it was returning a TON of fuel. So either the regulator was stuck and not letting any pressure build, or something else is dumping all the pressure back to the tank.
if you unplug it it goes to max rail pressure...if its not sticking.
But if its stuck full open (or closed??) my thinking was it was dumping all pressure that the CP3 was making, thus not even giving it a chance to build any pressure when cranking.
But im now wondering if it was the cascade overflow valve or some other part internal to the CP3...
is there a way to open her up and check that? I have never looked past the back plate that some have modded for more flow... chris I got your message i'll holler at ya after I visit the attorney.
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ok so for tonight we took teh pump out of the truck cascade valve appears to be in working order... aka the spring isnt broken and the plunger appears to be functioning smoothly. I took the wicked diesel FPR and plugged it in to the truck and when the key is turned on it moves from full open.
took the back of the pump off and spun the pump gear on the front and it also is functioning.
checked the back plate to see if the gears may be broken in there seems to be spinning freely.
last we took a manual guage ( only 2000 psi rating) and hooked it to the high pressure outlet. on the bright side for the pump the guage is now broken from being maxed out when we cranked the motor.... so we are now going to attempt to fire the truck again since it seems that the pump is making pressure.... would a bad rail pressure sensor cause a no start problem?
took the back of the pump off and spun the pump gear on the front and it also is functioning.
checked the back plate to see if the gears may be broken in there seems to be spinning freely.
last we took a manual guage ( only 2000 psi rating) and hooked it to the high pressure outlet. on the bright side for the pump the guage is now broken from being maxed out when we cranked the motor.... so we are now going to attempt to fire the truck again since it seems that the pump is making pressure.... would a bad rail pressure sensor cause a no start problem?
well we got it cranking and building 2600 to 3600 psi. plugged the injector relay back in and she fired and rain. then chugged and stalled. doesnt seem to want to hold pressure . possible bad filter head and its sucking air? got it to crank and fire a couple time but keeps chugging and stalling. primer seems to not want to get hard