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Twin Intank Pumps

19K views 41 replies 18 participants last post by  2filthy3 
#1 ·
I thought someone had done twin intank pumps before but doing a search I can't find it.

Anyone remember who did it and if there were pics of it.

I need to do something now because I've run out of fuel at 500whp @ 15psi on E85 with one pump today.
 
#2 · (Edited)
You dont need two pumps, just one big one. Check with HPF to see if this one is big enough. They offer bigger ones..
http://www.horsepowerfreaks.com/par...Pump_Install_Kits/E46_M3_Walbro_In_Tank/16889

From what I can find out, the 255lph is just adequate for your situation. That means you should look for a 300lph pump that fits in tank, if such a beast exists. E-85 is tricky. My info is from reports i read not from a real expert. Check with a really knowledgeable tech. But I think I got you in the ball park at least. GL.
(My pump is 1250 lph!)

EDIT: Bimmerworld offers dual in tank pumps, but for starvation reasons. You give up your fuel gauge when you use them.
 
#4 · (Edited)
LOL I have a 320lph in tank pump now and it's the one that has run out. I really need two of these.
 
#5 ·
DeatschWerks DW300. Not a fan of inline setup. Not even a fan of twin pumps. But I'd rather do twin than inline.
 
#15 ·
That looks impressive but I'm not a fan of inline pumps. I have found problems before when the intank pump can't supply enough fuel to the back of the inline pump it has really bad side affects.

I've also seen it where pressure builds up between the pumps and super heats the fuel and gives the inline pump a heart attack.

These are the two reasons I don't like inline pumps.

What I want to try and do is do twin pumps on the factory fuel pump hanger in the tank. I thought I'd seen it done before on here but maybe I'm thinking of somewhere else. Might not of been a BMW.
 
#23 ·
I pulled the syphon side out today to see what was there. There is no surge bowl area for a pump. But the biggest issue is I was showing just under 1/2 a tank on the gauge and that's exactly where the fuel was as well. All on the fuel pump side. There was no fuel at all on the syphon side. So I wouldn't like to put a pump on that side because it would run dry and have no surge area. So back to what I was looking at I'm going to run 2 pumps on the one hanger.

Now the joy of trying to make it all fit.
 
#24 ·
You want lift pumps up to a surge tank and then inlines from the surge to the fuel rail. I've got the OEM intank pump, then two Carter lift pumps, twin surge tanks and then four 044 inlines going forward.

 
#25 ·
That might be what I need but it's what I don't want. Don't want to take up boot space with fuel system. It's a street car.
 
#26 ·
Getting there. After a lot of cutting and hacking thery are sitting at the right level and now I just need a Y connector to join them up.

 
#27 ·
Finished and fitted. Now time for testing

 
#28 ·
Finished and fitted. Now time for testing
I doubt that will work out as good as running a Y connector outside the tank, mainly because the pumps will have to work against eachother , also a one-way valve should be fitted to the output of each pump..

It will outflow one pump though thats for sure :)

On a side note :
Is the Fuel level sensor thesame on both sides ?
If so you could just drop in another pump assembly on the driver side.

And whoever linked that 400LPH pump , it's rated at 40psi , i bet it drops really fast above that...
 
#37 ·
The siphon hose goes into the surge area on the pump side. Nothing to do with the basket
 
#41 ·
As I stated earlier the siphon arrangement can empty the left side of the tank so a pump on that side is a waste.

The CA automotive setup isn't a twin supply pump setup it's a pump in place of the siphon hose so your not relying on siphoning in long corners to supply fuel to the pump side of the tank
 
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