Outer Limits 4x4 Board

Hey Guys
Just wondering if anyone new offhand what type of fuel pump a 97 Coil Sierra runs. I'm presuming it's a mechanical pump. Has anyone done a conversion to an electric fuel pump off a vitara or something along those lines? I'm getting to the final stages of my supercharger setup and am now looking at getting the fuel from the tank to the carb. Are Vitara ones in tank or external? Or is it possible to buy just a universal kit?

Much appreciated.

Vits are internal.

what pressure do you need?

u can get aftermarket external efi pumps. (VL)

Well, it'll probably only need to be around 10-15psi. I'm not sure how much the standard pump can push, so I thought it better to be safe than sorry and hook up an electric pump with a regulator on it.

The Coily tank has a bolt in pickup/sender unit which has the same flange as a Vitara in tank pump. You can bolt the vitara pump in pretty easily. To get the fuel lines pointing in the right direction you may have to slot some of the holes in the pump flange.

They put out about 35psi I believe.

Ben

Just some thoughts Wasabi:

Coil tanks have a swirl pot in them - a vitara pick up bolts in with the in tank pump and will deliver 35-40 psi or so..... but htis is what an MPFI requires,not a carb.

Are you trying for boost refernced carb fuel pressure? This could be a bit of a minefield, but you have indicated before you have this sorted, so I can only comment on safety.

You will need safe reliable fuel pump switching or you might turn you sierra into a Jeep (bwahahahaahahaha I crack me up)

With eternal thanks to Mightymouse for this- it's lifted straight from the Vic Suzuki club forum:

One solution is a Bosch "Tachometric Relay".

The most common use ( and therefore wrecker available ) is off a
VK Commodore BOSCH P/N 0 280 230 005.

This is a multiple output relay that also has "cranking" and
"tacho" inputs. Fuel pump will be on whilst engine is cranking
and running but will cut out if neither signal is supplied after
around a second or two.

The connections are numbered on the relay - using standard BOSCH ID's

Terminals

30 + from Batt
31 -
15 + from ignition
1 Ignition Coil ( RPM Pulses )
50 Start Solenoid
57 Switched + for Injectors etc ( optional but good idea )
57B Switched + for fuel pump

Note : EFI fuel pump control is required by law. The consequences
of high pressure pumps left running in an accident are very severe.

This will safety switch a high pressure pump even in a carby car, otherwise parking the car with the ignition on could create some havoc, even ignoring the effect of a crash or rollover.

The coily runs a mechanical pump the same as a earlier model leaf sprung sierra. Here is the best option for you .....

remove the mechanical pump and blank off the hole in the head with a metal plate.

use a vl commodore inline fuel pump.

use a malpassi fuel pressure regulator , if you are unable to source one from a local supplier , i can get them.

now you cant use the standard malpassi that they supply for a efi car , as they are very unreliable at the low pressure you require as a "base" fuel pressure , eg 3-4 psi . you need to buy a "carby" malpassi regulator , it has a boost reference also like the efi models , you may also need to increase the size of the fuel return line back to the tank as the efi fuel pump will be pumping a lot more volume of unused fuel back to the tank.

once installed . it will give you the base 3-4 pounds of fuel pressure at 0 boost (so as not to flood the carby as the needle and seat cannot handle fuel pressures above 8 psi) as boost increases the fuel pressure will increase by 1 pound for every pound of boost.

now you also need to look at how your system is set up ... is it a suckthrough or a blowthrough setup , if you are using a blowthrough setup , you will need to address some issues with the carburettor , here are 2 issues that are prevalent with the stock coily carburettor that will not make it viable to run the stock carb.
1. the stock carb uses a "vacuum" secondary , obviously it uses vacuum in the venturi to open the secondary .. under boost there is no vacuum , only pressure , so the vacuum secondary will not work , boost will actually hold it shut ...
2. the accelerator pump , being the leather plunger type will not like boost at all , it tends to fold the leather back , then inflates the rubber boot on the shaft full of boost and fuel and tends to explode spewing fuel everywhere. you need a carby that uses a diaphram type accel pump, such as a webber , or a siilar type carb that has a mechanical secondary and also a diaphram type accel pump , these can withstand some pretty serious boost (ive run one on 19 psi before)

Im not familiar with your setup , so give me a pm regarding any info you need.

cj wrote:Vits are internal.

only if they are efi , carb vitaras use a mechanical pump the same as a coily and WT leaf sprung and earlier (the pumps are different , but its the same principle)

Thanks for all the tech guys. I've done an electric fuel pump conversion on my Mini many many moons ago, so I'm aware of cut offs etc for safety. For that conversion I just used a Rover EFI tank, pump, switches etc. I was kind of hoping to do the same with the Zook Looks like that VK Relay would be the go to switch it easily, thanks Steve.

Suzimad: I'm running blow through but using a different carb from standard. It's already setup to cope with boost, it's just getting the fuel there that's become the problem.. I've been looking at a few "Carby" regulators and intend on using one of these as you've advised. I just wasn't really sure whether the mechanical pump could put out enough to handle the extra boost, that's why I'm looking at electric fuel pumps.

Thanks again guys.

suzimad wrote:

cj wrote:Vits are internal.

only if they are efi , carb vitaras use a mechanical pump the same as a coily and WT leaf sprung and earlier (the pumps are different , but its the same principle)

Quite correct but the question was about converting to an electric pump so that is what I was answering in relation too.

Even if the mechanical pump could sustain the pressure required for a forced induction setup , for the price of a commonwhore fuel pump its not worth the risk of lean out and detonation.

Keep us updated how it goes.