Outer Limits 4x4 Board

i've posted this in the zuk section, but its more of a general question

at the moment i'm setting up my fuel system. i've got a fuel cell, a lifter pump, surge tank, external vl commodore pump and a heap of hose to join up. i've done a diagram below of how i'm thinking of doin it all, take a look and see if theres something i should change

the only thing i'm worried about is the lifter pump, its specs are 4-7psi and 132 litres per minute. sound about right for a lifter pump to feed a surge tank?

zooki suggested moving the return from the engine to the tank, instead of the surge tank but problem is, the cell only has three holes, two in the sump, and one at the top. will it cause drama's if i run the surge return to the hole alongside the outlet in the sump? and then have the engine return come back into the top of the cell???

In one of my books it says both options are pretty viable in regards to the return line. The preffered method is to do a return straight to the fuel tank provided the lifter pump can keep up with the engines demand for fuel. If you take the return line to the surge tank you have the possibility of heating up the fuel (as its cirulating around the engine fuel lines) which is bad for performance.

I wouldn't say that putting the return to the base of the main tank is such a bad thing. I see the only neative as it may stir up all the silt and sh*t thats settled at the bottom of the cell. If this is a comp machine would you be cleaning out the tank regularly or what? Wouldn't be to dificult to get another hole tapped into the top or side of the cell.

edit* just read the thread in the zook section and they've said pretty much the same thing

does the heated fuel cause 'that' much of a problem? i mean its a 1.6 litre suzuki motor, not really a performance motor. i cant really easily put a new return inlet in the fuel tank, as its a plastic fuel cell

antt wrote:i've posted this in the zuk section, but its more of a general question

at the moment i'm setting up my fuel system. i've got a fuel cell, a lifter pump, surge tank, external vl commodore pump and a heap of hose to join up. i've done a diagram below of how i'm thinking of doin it all, take a look and see if theres something i should change

the only thing i'm worried about is the lifter pump, its specs are 4-7psi and 132 litres per minute. sound about right for a lifter pump to feed a surge tank?

antt thats how i done the fuel system in trev and i have'nt had any probs yet but if heat is a factor where the tank is run the line back to the main tank

for got to ask ,what size fuel line's are u running . what brand off pumps ?

not sure on the line size, its a touch bigger than standard zuk stuff cause i couldn't get a reducer that'd fit the cell and the standard hose size.

not sure on pump brand either, they're not holley's or anything, just something from Thompsons. the main pump is a vl commodore one, and the lifter pump has the specs i said above (4-7psi, and 132 litres per minute)

Everything looks fine to me except for where you have the filter. I know in your mind you say put the filter before the pump and in a carb system this is fine because generaly you only run 3-5PSI fuel press. But with an EFI System they run around 32PSI constant and supply to the pump is very important so any restriction to the pump can cause the pump to fail premiturly. Also the Fuel on an EFI system can be returned to the Surge can eficiantly because although the fuel has allready been to the engine it doesnt get real hot. Fuel flows pretty fast through the fuel rail at 32PSI so doesnt get much heat soak.

From the specs on your lift pump and the amount of fuel a 1.6 will consume i doubt you will run the surge can out of fuel.

antt wrote:not sure on the line size, its a touch bigger than standard zuk stuff cause i couldn't get a reducer that'd fit the cell and the standard hose size.

not sure on pump brand either, they're not holley's or anything, just something from Thompsons. the main pump is a vl commodore one, and the lifter pump has the specs i said above (4-7psi, and 132 litres per minute)

i use'd a holley blue pump for the push pump 15psi and a vl pump as well for the high pressure . the setup u have should work great

Actually i cant imagine the specs on that pump are correct. 132 lpm is a lot? So every 30 seconds your going cycle your entire fuel tanks fuel through the surge can

cheers guys. i agree 132 lpm is high, i could be remembering it totally wrong, but i was fairly sure it had that on it

i'll get it checked out and find out for sure

RUFF wrote:Everything looks fine to me except for where you have the filter. I know in your mind you say put the filter before the pump and in a carb system this is fine because generaly you only run 3-5PSI fuel press. But with an EFI System they run around 32PSI constant and supply to the pump is very important so any restriction to the pump can cause the pump to fail premiturly. Also the Fuel on an EFI system can be returned to the Surge can eficiantly because although the fuel has allready been to the engine it doesnt get real hot. Fuel flows pretty fast through the fuel rail at 32PSI so doesnt get much heat soak.

From the specs on your lift pump and the amount of fuel a 1.6 will consume i doubt you will run the surge can out of fuel.

i didn't think off the fuel filter in that positoin tony. in mine the filter is after the h/pump . good call

antt wrote:does the heated fuel cause 'that' much of a problem? i mean its a 1.6 litre suzuki motor, not really a performance motor. i cant really easily put a new return inlet in the fuel tank, as its a plastic fuel cell

I'm really just going off what the book says (it is performance based). Basically the hotter fuel can lead to early detonation. It really depends on how stressed the motor is I suppose, if it takes it easy then I guess heat soak may not be a problem but if your revin the crap out of it you might notice it gets hotter quicker and detonation may become a problem. It goes on to say the bigger the surge tank, the less important the issue becomes (more fuel, longer it takes to heat up, bigger tank disapates heat quicker etc.).

Just looking at your lifter pump specs and I rekon 132l/min is gonna be plenty (f'ing huge actually - is it a holley carb pump or something or just a generic lifter pump?). According to this book the vl pump only flows 2.8l/min with no restriction anyway (2.3l/min@36-40psi). You might even find with that sort of flow with the lifter pump that the fuel cycles with the main fuel cell enough that heat soak does not become an issue.

edit* 5 replys already while I typed this. I'm way behind the 8 ball tonight.

now that i think about it, pretty sure it was litres per hour

edit: surge tank is 2 litre capacity

vl pump is a 'GOSS' brand one, still searching for specs on the lifter pump

antt wrote:now that i think about it, pretty sure it was litres per hour

edit: surge tank is 2 litre capacity

Thats 2.2l/min. In that case its probably a safer bet to return to the surge tank. After what RUFF said heat probably dwon't be an issue nd you risk staring the vl pump if ou thrash it for an extended period of time(2.3l/min vs 2.2l/min)

Run it back to the surge tank in case your lifter pump fails, you still have a two litre fuel tank. Im already on my second pump

Ans if you are using a fuel cell with foam in it put a filter before the lift pump This is why Im on my second pump

thanks for the tip rhett, the cell (jaz brand) has foam in it

i've found something on ebay that i'm pretty sure has similar specs to the lifter pump i'm got
http://cgi.ebay.com/12V-UNIVERSAL-ELECT ... dZViewItem

Thats pretty much the same as I have now. I can gt them for $35 new

And don't have you pickup in the surge tank right on the bottom as when your upsidedown its got no fuel

Rhett wrote:And don't have you pickup in the surge tank right on the bottom as when your upsidedown its got no fuel

bit hard to drive out of a roll when all 4 wheels are off the ground

You got a exo, you can give it a go

whats a drysump system worth

antt wrote:i cant really easily put a new return inlet in the fuel tank, as its a plastic fuel cell

yeah, you can. i did it with mine. just drill a hole and use a -8 bulkhead fitting and a couple of fibre washers.
if you are using a surge tank definitely run your return line into it.

i am going to run a big surge tank like 3 litres and return into the surge tank to ensure the tank always has fuel so on a steep climb you can get to the top without dramas. v8 supercars run an 8 litre surge tank returning into the surge tank thus having 2 laps warning about fuel refueling when the main tank is empty.

cheers bru

my suzi super car is 5litres