Looking at re-doing my old fuel lines and was hoping to add in an electric lift pump to my 04 LB7. I have seen the Fleece unit and it looks very nice, but a little more than I would like to spend. Got to thinking about if one of the stock GM lift pumps from a 2017+ truck might work. Was also wondering if by adding even a stock lift pump, how much power that might allow out of the stock CP3 setup. I know that adding in an external fuel pump / filter combination (FASS, Air Dog, etc...) takes care of any fuel supply limitations, but wasn't sure what kind of horsepower could be had with a stock LML fuel pump in the tank.
Does the L5P lift pump work in LB7 fuel tank?
- Thread starter turbo_bu
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2017 plus is l5p not lml. I'm not sure about actual fitment but it would be too much pressure for the cp3. I think l5p lift pumps put out in the area of 55 psi. Stock cp3 pumps don't like much more then 15 psi.
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L5P, sorry brain fade on that one. Also wasn't sure what kind of pressures that pump was putting out. 55 psi would be way too high.
if you do a regulator on the feed line, i dont see why it wouldnt work. I think you will have more issues with fitment and putting it all in than getting the pressure figured out. i doubt the sender and whole unit will drop in place but you never know.
You would probably be better off trying to adapt one from a 5.9l Cummins Dodge. They ran around 13-15 psi iirc. It would have to be a hybrid though keeping your sender and adding the pump into the bucket.
na, wouldnt hurt it at all. plenty of fuel pumps out there that can run 100psi but are regulated down to 40-50psi. As long as the volume can be returned, its a non-issue.
that's the kay. you can't dead head the pressure. to keep the pump happy you have to return the excess back to the tank. you can literally just use a pressure relief valve set at 15 psi and plumb it to dump into the return if you want to do it on the cheap
This. And considering how much hot fuel is already being returned to the tank in a diesel, unless you plumbed the return off the regulator back through the fuel cooler, you’re just adding more heat into the tank.
My point being, just use a low pressure pump. You don’t need all the pressure. If you really feel the need for a lift pump for a stock or mildly modified truck, a Kennedy Performance pump is plenty, IMO.
Thermally, you are not hardly adding any heat. Regulating down to 15 psi means you are supplying far more volume of fuel than you are pressure and pressure is where heat is created. You are not “working” the fuel and it allows you to add pressure down the road with tuning if you wanted.
There’s no reason to knock the thought of retrofitting a pump into the truck if he wants. There are far more benefits to him adding it than the negatives it may have.
Exactly. The volume they flow is even more than an l5p pump and it’s a non issue for heat based on what I explained
Even gasoline engines have pretty much completely went away from return style fuel systems because of how they work the pumps harder and put more heat in the fuel. I guess is hindsight it’s probably not significant heating but I would imagine that there would still be some, especially cutting the pumps pressure down that much. Anyone can make any mod they want, I’m just thinking (er, typing? Lol) out loud, that’s all. Personally, if I were to put a lift pump on my truck, I would love the simplicity of an intake pump over an externally mounted pump. Where I live, the winter salt kills everything under a vehicle.
and they are being driven by pwm or some other strategy to very the pumps rpm and thus output. since they can turn down the pump itself the is no need to return any fuel. I doubt the change has anything to do with heat but more to do with meeting demands of higher pressure without undue stress when it's not needed at idle, etc
True about them being varied and also true about how they are doing that to help lower stress levels. It’s also done to keep from returning hot fuel to the tank which causes more evaporative emissions. The emissions part isn’t an issue for diesel however.
As others have said, I think its a neat idea but likely far more trouble than it's worth. If you want a drop-in upgrade the Fleece is the best unit you can get (uses 2x newer Cummins pumps IIRC).
If you want to increase filtration, a FASS or AirDog are great options as well.
If you want to increase filtration, a FASS or AirDog are great options as well.
Since the L5P in tank pump uses a brushless motor, it isn't as simple as running a wire to the tank. You would need some sort of pump driver to make it work, and by the time you did all that, you would probably be money ahead to just buy any of the available aftermarket fuel systems.
