# help with wiring new fuel pump/surge tank.



## mattysupra (Oct 31, 2008)

Before anyone says, yes i have searched but cant find a 'direct' answer.


Right then, i have fitted a surge tank that is supplied with fuel from my old in-tank pump. From the surge tank to the engine i have fitted a bosch 044. 

How do i wire the bosch pump in? Do i just simply fit a relay and pick up an output from the existing wiring to power my 044 and leave the intank (old pump) connected as normal?

Does the car turn on and off the fuel pump as it needs it or is it always running when ignition is on? If it turns on and off on its own, will the surge tank struggle to fill as the 044 will keep stealing the fuel before it gets full?

Or does the pump always run ? If it always runs then i cant see there being a problem. Just worried incase the ecu turns it on and off as it wants fuel. 


Thanks.


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## GT-R Glenn (Nov 9, 2002)

How do i wire the bosch pump in? Do i just simply fit a relay and pick up an output from the existing wiring to power my 044 and leave the intank (old pump) connected as normal?

YES / I hardwired mine to the battery through a relay and switch it using the oem pump wire

Does the car turn on and off the fuel pump as it needs it or is it always running when ignition is on? If it turns on and off on its own, will the surge tank struggle to fill as the 044 will keep stealing the fuel before it gets full?

Umm no, the factory lift should fill the surge tank, the fuel rail return should go to the surge tank and the overflow from the surge tank returns to the oem tank
The 044 picks up from the bottom of the surge tank


Or does the pump always run ? If it always runs then i cant see there being a problem. Just worried incase the ecu turns it on and off as it wants fuel. 

Mine runs all the time the ignition is on / theres no reson why you couldnt put a switch in the cockpit to isolate it as well.


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## pupsi (Aug 29, 2006)

And install a bigger inlet return on to the main tank (enlarge the original) for the return from the surge tank. I didn't do it (being done now) I have 2 Bosch 044's and the pressure found the weakest spot in the welds and started leaking on the surge tank.


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## rb30r34 (Jun 30, 2008)

pupsi said:


> And install a bigger inlet return on to the main tank (enlarge the original) for the return from the surge tank. I didn't do it (being done now) I have 2 Bosch 044's and the pressure found the weakest spot in the welds and started leaking on the surge tank.


Yes, this is important. The return must be able to handle more fuel than the pumps can flow.
This is because when the car is idling, both the lift pump and the return line is filling the tank. If the overflow line is to small to handle the flow of both pumps at the same time, the tank will pressurize.
This causes the surge tank to flex under pressure, which will result in a fracture of a weld over time. This will occur at the welds weakest point, usually in the middle of the longest weld on the tank.


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## mattysupra (Oct 31, 2008)

what size return pipe? I have done mine in -6. How do i connect a bigger pipe to the tank return? In fact how have you lot connect the braided hose to the top of the tank? And to the fuel lines leaving the tank to the engine? 

Will i still need to inlarge the return with one 044 and the standard pump in the tank? Im looking at 600bhp so i think im just about covered running one 044 am i not?


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## miragev (Apr 11, 2007)

can we get some pictures of this up so it can be explained it detail as a reference for the future


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## AlexH (Aug 17, 2008)

miragev said:


> can we get some pictures of this up so it can be explained it detail as a reference for the future




thats a real good idea, im plumbing in a tank soon too and these questions were about to be asked too, but matt beat me to it and i found tyhis thread with the search engine


alex


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## Adam Kindness (Jun 22, 2002)

this is roughly how mine is plumbed in (ignore the addion of a fuel sampler coupling). I have twin pumps and twin 'feed' lines running to a twin entry fuel rail though, with a single return from the rail to the top of the surge tank.


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## Adam Kindness (Jun 22, 2002)

wiring wise: I have my external pumps wired direct from the battery off a fused relay. The relay is switched by the OE pump.


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## Adam Kindness (Jun 22, 2002)




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## mattysupra (Oct 31, 2008)

Why is your fuel filter on the return? should that not be inline with your tomei pump or just after the surge tank before your 044's?


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## Adam Kindness (Jun 22, 2002)

prob buggered that bit up in the diagram.... its prob on the feed from the OE tank to swirl.


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## mattysupra (Oct 31, 2008)

Adam Kindness said:


> prob buggered that bit up in the diagram.... its on the feed from the OE tank to swirl.


I thought so! I was getting worried and confused then!


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## pupsi (Aug 29, 2006)

mattysupra said:


> Why is your fuel filter on the return? should that not be inline with your tomei pump or just after the surge tank before your 044's?


Thats right, mine is also on the return, in between the surge tank and the main tank, dont know why, but thats how its plumbed in. So Adam's is in fact correct.


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## pupsi (Aug 29, 2006)

Matt, the inlet pipe on the main tank return, replace that for a bigger diameter return, not the pipe, but the metal pipe that sticks out from the main tank. If you understand what i'm trying to say.


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## mattysupra (Oct 31, 2008)

maybe mine being a 34 is different? But my pipes sticking out the top the tank are plastic not metal. They are all moulded together also. When you lift the round bit out the tank the breather/return and the flow pipe are all moulded together with what looks like valves etc. 

But my return pipe is the same size as the flow pipe tho. Are yours the same size or smaller in the first place?

And how did you connect to the old fuel pipes? Are yours plastic or metal also?


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## mattysupra (Oct 31, 2008)

pupsi said:


> Thats right, mine is also on the return, in between the surge tank and the main tank, dont know why, but thats how its plumbed in. So Adam's is in fact correct.


surely that cant be correct? That would mean that if you filled up with petrol and it had crap in there, well it would travel all through your fuel system, through your injectors and all the way back again before it gets cleaned/filtered! 

I would defo of thought the fuel filter should be before the fuel pump to protect that from dirt and defo before it gets its way to the injectors and blocks them up?


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## pupsi (Aug 29, 2006)

Don't forget you already have the OEM filter in place. This filter is for the new line you're running from the surge tank. The inlets on the main tank are plastic except for the ends which are metal on my 33, thats what you need to enlarge. I'm actually going to have 2 returns from the surge tank to the main tank now. Don't want it to start leaking again.


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