LB7: Lift pump pressure
- Thread starter DieselDummy
- Start date
10 ish PSI I believe. Anything much above that you might have idle issues or possibly develop a leak. Bottom line as long as you remain positive in feeding the CP3 your good.
Well I have a pump I want to use but it will only go down to 14psi, wondering if it will hurt or not?
Sent from the road!!!!!
03 lb7 CC/LB
Sent from the road!!!!!
03 lb7 CC/LB
Think it depends on year. IIRC the LBZs+ can handle a little more pressure and stay happy?, mine runs at 12-14psi with no issues.
the issue is in the FICM. it seems some trucks that have a lift pump with over 12psi can cause a lopey idle. The LBZs and up dont have to worry about this since they dont have an external ficm with fuel running through it like the LLY/LB7. Im running my AD II at max pressure (the adjsuter all the way in) and its netting me around 13-14psi and no lope issues. Some trucks dont mind it, some trucks dont like over 10psi
Mine at 17 was causing high rail pressure at idle, 13 is almost too much still. No fuel in my ficm either
I've had a bunch of trucks start a small leak at the top of the filter head, where the wire plugs in, with 12+.
That's why I thought 10PSi max was a good guide line to go by. I mean 10,12,15,20 PSI really makes no differences as long as your supplying ample fuel to the CP3. Really even at 5,6,7 PSI as long as you have a guage thats showing at WOT with your biggest tune is still supplying enough fuel not to go negative or no PSI ,that is the goal.
I don't see the point in pushing more PSI then necessary or your just asking for trouble. Of course depending on your setup for example dual CP3's you'll probably need max PSI but for most 10PSI is a good guide line. IMO a guage is necessary
I don't see the point in pushing more PSI then necessary or your just asking for trouble. Of course depending on your setup for example dual CP3's you'll probably need max PSI but for most 10PSI is a good guide line. IMO a guage is necessary
Don't know for sure you'll have to be the judge of that. What you can do is buy a separate regulator and plum that into your setup then you can regulate it.
Shane at wicked diesel made it a point to say that 20psi is an optimum pressure to run a lift pump at when your running big tunes on modded cp3 at WOT but can only help a stock one. i wish there was an explination as to why but i can only speculate that cavitation still happens in the pump even with a lower positive pressure due to the pressure the cp3 is trying to create, its speed and the heat generated. Im probably way wrong though
http://www.duramaxdiesels.com/forum/showthread.php?t=24238
We run a Holley Black (14 psi) on our LB7...It had issues at idle, so I put it on a Hobbs/pressure switch to turn on at 2psi boost...No problems for 4-5 years...
super diesel
<<<< Under Pressure
1 lift pump on the frame (standard), then 1 (nice to have it at 14+ psi or higher) under the hood (against the pass. side quarter p.) with a check valve with no spring for a bypass around it when it's not running. Put it on a pressure switch set for 10-14 psi and plum it in line (after the FICM and plunger on the OEM filter if you have one). The pressure will equal the pressure of both pumps together when the 2nd one is tripped. The fuel needs to be filtered before the 1st pump and they will all live in harmony for years. Ran this set up for 6 yrs. Just my 2cents.
I also always put a check valve around my pumps in case they fail (for free flow). I wont get stranded.
I also always put a check valve around my pumps in case they fail (for free flow). I wont get stranded.
I run the FASS 260 at 18psi no problems on White Out with dual CP's, use two filters, 2 micron in one mounted on the frame rail and the stocker, although I thinking about taking out the stocker.
Im running 9psi at the filter head and dropping to 0 on my biggest tune 2 psi on the 4th tune and 4-5 on the other tunes. I am going to turn it up until it lopes then back down till it stops and then run and check it. if that dont work im going to try a boost refrenced regulator after my pump.
I'm by far no expert but I believe we are talking to different beast here.
1) Modded fuel system
2) Stock fuel system
For the average Joe Duramax with a big tune hell I don't even know if this guy has a big tune or even a built transmission to handle it. So I'm not going to recommend something that might ultimately give him a problem from a shitty idle or a expensive bulging leaking FICM! Or any leak for that matter.
So I'll play it safe and recommend 10 PSI or lower. If you gents want to,throw the kitchen sink at it, be my guest.
Yes there are many fancy pump set ups to be had and when you start to really or want to mod your truck then perhaps (more than likely) my suggestions might be incorrect. But for now I tend to be safe making suggestions. So I'll step away and watch and learn
Ta ta
1) Modded fuel system
2) Stock fuel system
For the average Joe Duramax with a big tune hell I don't even know if this guy has a big tune or even a built transmission to handle it. So I'm not going to recommend something that might ultimately give him a problem from a shitty idle or a expensive bulging leaking FICM! Or any leak for that matter.
So I'll play it safe and recommend 10 PSI or lower. If you gents want to,throw the kitchen sink at it, be my guest.
Yes there are many fancy pump set ups to be had and when you start to really or want to mod your truck then perhaps (more than likely) my suggestions might be incorrect. But for now I tend to be safe making suggestions. So I'll step away and watch and learn
Ta ta