Can you use a inline fuel pump at the same time as an intank fuel pump? If so, won’t the inline fuel pump overpower the intank one? Is there any advantage to using both than to using a single one?
Honestly , I also needed to know this :lol: .
I did not feel like removing the sending unit on my car but wanted to upgrade to an inline pump .
Let us know ,
Well I asked 2 people on MSN, one said yes, and one said no. This issue needs to be made clear. I am thinking since inlines are usually more powerful, the intank fuel pump will be pointless or maybe just act as a fuel filter since the inline is sucking out of the intank faster than the intank is delivering. Very curious
I think with such a set up you need to use a surge tank. The in-tank pump fills the surge tank and the inline goes after the tank so when fuel is in demand then there is a surplus for the more powerfull inline. Not posative put I think thats how it goes.
Would the surge tank be located in the trunk? or closer to the engine. I can understand if it was closer to the engine it would help boost performance a bit because of travel time.
Whats a popular set up for dual fuel pumps. If one fuel pump can support only 300 hp and you have 500 hp, what do you do (using 2 fuel pumps and not a better single one)
use a walbro thats more fuel than you’d ever need?
some times its all youll ever need , ive see nthem not be enough before
if u have a walbro in there already u can use an inline booster pump such as the msd units , but if u are running a stock pump i dont know cause i knoe some stock pumps will not allow fuel to be sucked through at a rate higher than the stcok pump can output, but that is only on some cars , i think it should be ok on the nissans though…
and if u do have a walbro and its not enouhg that is most likely cuz u are still using the stock wiring , there are numerous writeups on how to re-wire your fuel pump to flow higher without damaging the fuel pump
but if u do use an inline pump it will just suck through the intank pump
use a walbro, using two will create weird pressures inbetween them and eventually fry one or the other… or just restrict flow, and you would load the circuitry running both, and if you just turn the intank one off, it mihgt restrict, walbro swap is easy
YES!!! you can use an inline with an in tank!!!
this is very simple practical physics kids…
as the pressure increases it reduces volume of flow… an inline pump will reduce the in tank pumps need to increase pressure allowing it to increase volume of flow. This is how multi floor buildings keep pressure up…
With Two pumps in the system Volume will increase dramatically, to get the flow rates you will need to to get a flow/pressure graph on the Inline and In-tank pump.
one pump requires a check valve… it’s that simple.
surge tanks simply reduce the possiblity of fuel starvation in high G cornering/loading. A properly built surge tank setup is going to cost more then 99% of the people here are willing to spend on this particular subsystem.
Do they have to be the same pressure? The inline fuel pumps are usually more powerful. Do you connect it right after the intank fuel pump (after the sending unit) in the trunk on the same line? Will it overpower the inline forcing it to feed faster if it is not pumping the same amount of fuel? A quick messy diagram would be nice 
My reccomendations to you is to get a professional shop to do the installation… inline pump requres a switched PS to the ign2 as well…
SARD makes a 280 pump ( in comparison to walbros 255) that will do the job you want. if you don’t have the inline yet then look into getting the SARD FP.
nice to know we have some engineers on the boards 
Whatever the max flow of the intank pump while pumping though an open line (no pressure), that and only that is the max flow you will ever see with the intank pump there. This is regardless of how big the inline pump is. If your system requires more fuel flow then that max the intank pump is a restriction, there is no way around it.
Your not explaining that well , your making it sound like their is no flow at all with no head. if you look at a typical displacement pump graph, most of these pumps WILL flow WAY more fuel then thier ’ 255lph ’ rating at 38.7-40 psi.
http://go.mrgasket.com/pdf/Fuel_System_Products.pdf
the first pump is very similar to a standard intank pump in terms of flow, look at the graph and see just how much fuel will flow when the actual work load is reduced to say 1/2 …
anyway, unless your pushing big numbers and large injectors then you can get away with your std fuel lines… but if your planing to run a secondary pump then you might as well run a -6 hard line from the inline pump… on second thought I won’t complicate things… let a professional shop take care of your fueling systems… but just as an example of what I do with a 450+hp rotary, I use twin intank 255lph with said check valve on one into a -8 high pressure hard line, to a multi port return FPR and a -10 low pressure return line.
I feel that is pretty well the best way to explain it without introducing any numbers. I could have said “with intank pump producing zero head” but “no pressure” is the same thing. I agree with you, infact, that is what I am saying, the intank pump will flow more than its rating at a lower pressure, absolutely. What I am adding is that if you drop the intank pressure requirement to zero (just enough to get the fuel through the hose to the inline pump) and your max flow is still not enough you are shit outa luck. The intank pump is then a restriction.
I personally wouldn’t set up a fuel system like this for many reasons but it could be done. My feelings are if you have a reason to need that much fuel design a proper system with a good pump or two and lines that are more than adequate. As an example, if the intank pump decides to fail(either mechanically or from lack of power from the wiring haress) I can’t imagine the inline pump is going to be able to suck enough fuel through it anymore. You then have an expensive inline pump that can’t do shit, IMO.
I say just put a walbro in for $120 and be happy
you need to know the users original intent… that’s the only way to make an informed suggestion