Carbie To Efi Fuel Questions

[BlueSuzy]

Hi All. I have a 1.3 carbie sierra and is being converted to a 1.6 efi.
Do i need a surge tank for my fuel system?

I have talked to some guy at auto one and he says i wont need 1, If i use an external fuel pump....A large high pressure filter (falcon)....and a standard 1.6 regulator. He reckons that the larger fuel filter will act as a surge tank because of the size of it.....and the size of my motor (which is still a baby 1)

And then he was giving me his life story about his race boat bla bla bla most high hp motors use surge tank bla bla bla like his.....

So i dont know what to believe, i am so confused.Pls Help!

[nicbeer]

depends on ur $$ and how u want to set it up.

i went the cheap method with mine without one and not had any problems even on inclines. thou low fuel can have probs but u always are really.

i used a carby style lift pump S3 bluebird has them i know. and then into the
vl skyline high pressure then to the fuel rail.

i tried one pump only (vl one) and had a few issues with stavation.

[mkpatrol]

Depends on how the pickup is set up in the tank.

Normally the float bowl in the carby is the surge tank/fuel supply & soaks up all the air in the fuel lines if it has a momentary non supply from the tank.

I would recommend a surge tank to be safe & high pressure electric fuel pumps dont really like to be run without fuel in them.

[BlueSuzy]

lookin at some surge tanks to go in suzy at the moment, Whats the cheapest people have come across? Seen 1 for $140 at a performance parts / bling clear taillights shop etc.... Base of it was about 100mm Diameter x 150mm tall i think....

[MightyMouse]

The type of HP pump has an significant bearing on the answer. If its a roller cell pump then any absence of fuel will result in significant wear and failure in a very short time. Centrifugal styles however don't rely on fuel as the lubricant and are much more tolerant of "running dry" for a little while.

Neither type like long periods of no fuel however as they use the fuel flow to cool the motors internals.

Sucking fuel from the tank can also be a problem, especially on hot days as if your unlucky the fuel will flash to vapor and also cause pump cavitation problems. The nearer to the tank and at the tanks level they are the less likely to suffer from this type of problem.

Surge tanks and feeder pumps are a requirement for cars that generate high G forces as the fuel in the tank shifts away from a central pickup. Track cars often have a pickup / pump in each corner of the tank feeding a header tank that contains the HP pump(s).

The in tank, lift style EFI pumps are very reliable and trouble free. Even if you had to do some work on the tank to fit one, they are pretty much idiot proof once done.

[BlueSuzy]

i was going to put the surge tank in the corner of the tray of the sierra, Then the hose will go through the floor, then the pumps/ filter under the floor, then running up to the fuel rail as normal.

[Gwagensteve]

The in tank, lift style EFI pumps are very reliable and trouble free. Even if you had to do some work on the tank to fit one, they are pretty much idiot proof once done.

Are you paying attention Bluesuzy?

I think the going rate for a EFI vitara tank is about $400. It does require mount modifications to fit, but it will then last for years and years, run quiet, and have not more connections than the stock fuel system. a vitara tank (or a coil sierra tank with a vitara pick up and pump bolted in) already has the swirl pot inside the tank so there is no need for a surge tank. I have set up 5 sierras this way and it has never given any problems at all.

A lift pump/surge tank HP pump is very expensive to set up - once you price up all the parts - and will be massive overkill for 65kw.

It will also take up room in the tray, is illegal to have in the passenger compartment, and have wiring, terminals, relays, heaps of hose clamps etc all to potentially give trouble.

I have seen two surge tank setups in SWB sierras and they were a PITA - messy, noisy and with heaps of interior space lost.

The guy you spoke to about pumps might be right- there will be a fair head of fuel, but leaning out because of fuel pickup problems and having a HP pump sitting down at chassis rail height is a concern for me.

Steve.

[MightyMouse]

I'm now a little confused....

The normal layout for a header tank system is a low pressure pump ( or pumps ) in or at the main tank feeding the header tank about a third of the way up. The header tank has a fuel return line up high that allows excess fuel to flow back to the main tank. The header tank is therefore always full when running and about a third full when stopped.

The header tank is kept close to the main tank as fuel is less likely to vaporise in a HP line than a LP one - and its probably more convienient / more room down the back.

fuel is then drawn from low down in the header tank by a HP EFI pump that supplies the engine. Return fuel from the fuel rail can either go back into the main tank or the header tank ( into the main tank keeps the fuel cooler but can require a larger LP pump ).

There are probably a million different ways you can plumb your system - but as I have described it is the "standard" way to run a header tank system.

Hope this helps.

[pig75]

This might help