Fuel Delivery - EFI

[NiXoN]

G'Day trendsetters!!
I'm in the process (yes, still) of doing an engine conversion....
http://www.outerlimits4x4.com/PHP_Modul ... hp?t=77174....
and i am wondering about fuel delivery. Typically i hear people are using a surge tank of some description to keep pressure up to the injector(s). I am thinking that by running a similar setup to a commondore (VL for example) I might be ok??!!! This settup ins made up of a low pressure type pump, in the tank, follwed by the high pressure unit a little fuirther up the line. Im under the impression that the first pump 'primes' the high flow one. How close/far am i from a workable system?? anyone else have the 'in tank' type settup (The coily tank has a lovely access point which makes the intank reasonably easy to sort)
Many thanks
Rob

[Spike_Sierra]

i run a vl pump. works fine and havnt had any dramas, but i think it would be better to run a primer pump, either in tank or external. Datsun bluebirds(series 2) use external electric primer pumps.

[beaver700]

do you still need to use a surge tank for a primer pump?


Martin

[1Lzook]

i run a universal electric fuel pump that u pick up for about $80 from repco that feeds the surge tank and from the surge tank to the fuel rail i have a vl turbo pump, you can pick these pumps up for around $160, i got mine off ebay, as for the surge tank i found a bloke selling a 2L tank that was brand new. i also got a braided line made up that runs from my fuel pump to my fuel rail, this probaly isnt necessary but it is a high pressure line.

here is a link for a fuel pump
http://cgi.ebay.com.au/GENUINE-BOSCH-91 ... dZViewItem

[lay80n]

Here we go. A surge tank is a smaller tank that a low pressure pump primes in a EFI system. The surge tank is used to keep the fuel constantly up to the high pressure pump, as any air bubles in the line caused by fuel surging round the tank would cause engine coughing and spluttering if they are allowed to enter the line. By pumping the fuel with a low pressure pump(remember that even crappy pumps can supply the right volume if they are at low pressure, hence the reason your lift pump can be small) into a small chamber, either internal to fuel tank (swirl pot) or external. The fuel is then taken from the bottom of this tank (any air or excess fuel is bled of back to the tank from a hose connected to the top of the surge tank) by the high pressure pump, and fed to the fuel rail. After passing the injectors any unused fuel passes through the fuel pressure regulator then returns to the tank via the fuel return line.
The swirl pot i mentioned is just a small sectioned of portion of the tank that keeps a constant amount of fuel in it (supposedly) to ensure that air bubbles do not enter the fuel stream. Typically cars with swirl pots only have one fuel pump (high press unit) and do not run external surge tanks. The surge tank is probably the better option as for performance, but uses more room and is more costly to set up.

Layto....

[NiXoN]

Good Info Guys, Cheers!!

As i got a high pressure pump with the engine, ill be using that one, pretty sure its a bosch. Im think ing that a turbo one might be a little bit of overkill for a single point injector, but i guess the more the merrier - it'l just end up back in the tank anyway.
I have rigged up the internal pump and it cetainly looks like it will work a treat...might worry about a surge tank if required later.
I am wondering a little bit about the internal pump elctrics settup - I have all the factory plugs etc, but am surprised to see that there are effectively 2 'naked' terminals inside the tank. They are securly clipped onto their respective posts, and separated by a 'divider'...i guess petrol doesnt contuct electricity very well??!!!!

Keep em coming

[Midget]

I run a TBI setup and use a VN V8 fuel pump,But lately i found that it's over fueling to buggery...After some from Jason from TOTAL CARE 4WD hopefully we have it sorted,Worked out the fuel pump was putting out to much pressure,Approx 39psi,When the TBI unit runs around 15psi..

I'm waiting on a fuel pressure reg so i can reduce the pressure..

Jamie

[lay80n]

Good Info Guys, Cheers!!

As i got a high pressure pump with the engine, ill be using that one, pretty sure its a bosch. Im think ing that a turbo one might be a little bit of overkill for a single point injector, but i guess the more the merrier - it'l just end up back in the tank anyway.
I have rigged up the internal pump and it cetainly looks like it will work a treat...might worry about a surge tank if required later.
I am wondering a little bit about the internal pump elctrics settup - I have all the factory plugs etc, but am surprised to see that there are effectively 2 'naked' terminals inside the tank. They are securly clipped onto their respective posts, and separated by a 'divider'...i guess petrol doesnt contuct electricity very well??!!!!

Keep em coming

If your running the TBI style setup, take note of Jamies post. Running a multi point injection pressure (40psi approx) will overfuel it, as Jamie said they need about 15psi for TBI setups.


Layto....

[sierrajim]

I run a TBI setup and use a VN V8 fuel pump,But lately i found that it's over fueling to buggery...After some from Jason from TOTAL CARE 4WD hopefully we have it sorted,Worked out the fuel pump was putting out to much pressure,Approx 39psi,When the TBI unit runs around 15psi..

I'm waiting on a fuel pressure reg so i can reduce the pressure..

Jamie

Didn't you fix that at Ozrock with a BFH?

[Midget]

I run a TBI setup and use a VN V8 fuel pump,But lately i found that it's over fueling to buggery...After some from Jason from TOTAL CARE 4WD hopefully we have it sorted,Worked out the fuel pump was putting out to much pressure,Approx 39psi,When the TBI unit runs around 15psi..

I'm waiting on a fuel pressure reg so i can reduce the pressure..

Jamie

Didn't you fix that at Ozrock with a BFH?

Na not really,I was only mucking around with a few things to try and reduce the fuel pressure.

I got my regulator late yesturday arvo and fitted it up last night and dialled it down to 15psi and the engine runs heaps better,Just have to re-adjust the computer now with the injector timing...

[Drew]

biggest problem that ive had with the tbi is the return line ,
the stock 1 is way to small, use at least 6mm i d & the same into the tank.
also the tbi has a inbuilt reg.

[NiXoN]

Cheers Drew! Ive got my fingers crossed the coily return lines are a bit larger - 6mm rings a bell,if not at least i now know!!! I was wondering about the pressure regulator - cross another thing off the list!
Many thanks

[beaver700]

Gday,

I am sorry, I know people are getting frustrated with me, but does anyone know what pressure the fuel needs to be to supply the fuel rail in a g13b engine?


thanks

[Spike_Sierra]

im pretty sure anywhere around 35-40, as they are MPI. Vl pump will work a treat.

[beaver700]

Thanks for the quick reply spike.

Also if you are using a surge tank, where is a good place to mount it do you think? I wanted to put it as close as possible to the fuel tank, but is it possible to put it in the engine bay, if you use a higher pressure primer pump?

just some thoughts,

thanks
Martin

[1Lzook]

i have got mine mounted on the passanger side against the fire wall in the engine bay where the charcoal box is supposed to be,