Wiring a dual pump setup in a single pump car

[Massive Lee]

Away from a crumpling zone. That's for sure.
But it could be in or under the car. When using NPT-to-AN fittings, the fuel system becomes bulletproof.

The easy way is to make a surge tank the size of the fuel filter, and swap it. Then perhaps relocate the fuel filter in the same area, or near the firewall.

Lee

[FredK]

That type of tank is pretty much what I was looking for, but could not find as an off-the-shelf item.

In terms of safety, I'm assuming the best place to put a surge tank would be away from the crumple zones of the car, and outside of the car?

[Massive Lee]

Hi Fred. It is indeed pricey. What I used to do is pretty simple.

The pump in the tank can be a pre-pump or a standard high pressure pump. This pump feeds a surge tank thant can be located under the car, most likely where the filter used to be, or in the trunk. This surge tank can be made from a 3" or 4" aluminum tube, capped, and with four 3/8" NPT fittings. Volume can be from 0.5l to 1l - 0.5l means you can run the engine with the feed dry for 45 secondes.

Here's the sequence for the inlets outlets.

- Feed from the intank pump
- Return to the tank (located as high as possible)
- Feed to the main pump (located as low as possible)
- Return from the fuel rail in the engine bay (location doesn't matter)

I used to produce them for the e30 crowd, as well as for our e46 racecar. You can literally feed the engine while the tank is under a couple of liters of fuel. Drifters and racers love it.

Lee

[FredK]

It's a pricey solution to a problem. I haven't really seen any other off-the-shelf surge tanks, but maybe I'm just not looking hard enough?

[Mr Deagle]

Splice on signal to a separate relay to the 044.

That tank thing is way too much money also.

[purebmw]

have to use a double 87 relay, to activate both pumps... its easy..., leave the same signal to de 85 from the ECM, leave it, anyway, you want to better your flow and volume, not pressure...

(when i say double 87 relay, is a 87-87a relay BOSCH)

[FredK]

I wish to add a surge tank and Bosch 044 pump to my single fuel pump car, using this:

http://www.intengineering.com/Integrated-Engineering-p8917399-1-2.html

The surge tank will be fed by the stock 318is fuel pump, which is traditionally under the control of the fuel pump relay.

Now, with the addition of a high current 044, I will use best practices in terms of the wiring with regards to electrical safety and weatherproofing. However, I am at a loss as to the control wiring. Do I just have the DME control the 044, and run the in-tank pump 100% of the time? Or should I splice the ON signal from the fuel pump relay between both pumps? Or is there some other scheme that I'm missing?