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  • 1 month later...
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  • 4 months later...
hey what happens if you install a higher flowing fuel pump and a pressure regulator but dont put in bigger injectors? would the higher fuel pressure be enough?

This is very dependant on how much power you are trying to gain. For a small power increase, bumping up the fuel pressure a bit is fine. However if you increase it too much you may start having trouble getting the car to even idle properly as the increase in fuel pressure actually makes it harder for the injector valves to open, meaning that there is a delay beween when they are turned on & when the valve opens to flow fuel properly.

I did this experiment myself once on a set of VS commodore injectors & found that a small pressure increase would give a higher flow, but increasing it by much more than half a bar gained nothing. The other affect it did have however when the pressure was increased further was that they would then flow dangerously low when pulsed on & off (as they would normally in the car unless you are maxing your injectors out), meaning they'd make the car run lean.

So as I said before if you want a small power gain it's fine to increase the pressure a bit, but don't get greedy. Ultimately if you are looking for a big power gain, getting a set of high flow injectors is the go :D

thanks for that. sounds like the best idea is to try and keep the fuel pressure the same & keep an eye on fuel pressure during w.o.t if it drops then the pump cant produce enough flow and should be upgraded. sound about right?

^^ Yeah I have to agree that doesn't make any sense. If the pump fuse is disconnected you won't get any fuel. You should just turn the ignition or & off a few times for the pump to prime the fuel lines & rail. If you disconnect the fuse you get zip.

thanks for that. sounds like the best idea is to try and keep the fuel pressure the same & keep an eye on fuel pressure during w.o.t if it drops then the pump cant produce enough flow and should be upgraded. sound about right?

Yes this is pretty well correct, the moment you see the pressure dropping you know the pump is struggling, & if you're running higher boost or increased regulator pressure, it will have to try even harder. However if the car is leaning out & the pressure doesn't drop, check that your injectors are not going flat out. If they are it's either time to give the reg pressure a slight tweak, or if it's leaning out badly, new injectors.

Edited by Electro
  • 2 months later...

bit of a noob question, but anyway. If you install a pump that flows more fuel will you get any benfit from it if you keep the standard fuel pressure regulator? Also, I presume the car would require a tune after the fitment of a larger fuel pump??? Or the car would be running rich?

bit of a noob question, but anyway. If you install a pump that flows more fuel will you get any benfit from it if you keep the standard fuel pressure regulator? Also, I presume the car would require a tune after the fitment of a larger fuel pump??? Or the car would be running rich?

I'll start off by saying that you might need a larger fuel pump if the pressure in the fuel lines is not enough, or dropping at higher revs.

So, for the first question, if you have adequate pressure and you fit a new fuel pump, then the answer is no, you wont benefit. Most of the time, gtst fuel pump don't supply enough pressure because they're old, or whatever, so you will typically benefit.

Second question. if your original fuel pump wasn't supplying enough pressure, and you had your car tuned, then you will probably need a retune as the ECU will have been tuned to compensate for the drop in fuel.

If you have stock ecu, then the tune will be what it is supposed to be from factory, instead of too lean. However, stock tunes are generally rich anyway, for which you need some kind of aftermarket engine management.

  • 4 months later...

For those of you who are going to install the Walbro yourself:

When you take off the plastic nut, make sure you dont use a flat head screwdriver that is sharp and new you will f**kup the nut.

When you use the filter that came with the pump you'll notice it is significantly smaller than the drop down in tank floaty type one that the stock pump uses. Installing the one supplied by walbro will result in 1/4 tank issues and even 1/3 tank issues if you dont mount the bracket low enough...

Don't fret though. Walbro have seemingly placed a nice little nubby next to the suck hole to slip the stock drop down type filter right on the end of the pump and you will be able to use it on the stock assembly without modding too much (maybe a cable tie or a rubber sleeve).

When you mount the assembly back into the tank, make sure that you do so carefully and slowly and clear any tools from the fuel tank opening beforehand. If you use a torch and get a mate to help u out to point it at the mounting bracket on the side of the tank dead ahead of you, you will see it has a seperator to which the fork on the top of the mounting bracket goes over for it to slip on to. If you positioned the drop in tank filter on the Walbro correctly you will find it slides right down to the bottom and, as ive tested, it sucks right to empty.

good luck.

Im still using my stock one. no probs :)

Just did my Tomei fuel pump install on my GTS-t. I left out the supplied fuel regulator too. Also plan to upgrade to a Sard FPR or Turbosmart unit when I get my Power FC mapped with some new 550cc injectors. Pretty easy job. Did everything inline with your original post. A couple of tips I may add:

1) I applied a small amount of lubricant to the black threaded collar as it was a bit tricky to get started when I went to put it nack on.

2) I made doulbe sure no spark could be triggered by other electrical wires in the boot whilst working on an open fuel tank (fumes) by disconnecting the ground wire directly from the battery after I de-primmed the lines.

3) Make sure you don't let the screw-type hose clamps don;t fall off into the tank. I wouldn't like to try and fish them out if they did...

4) Nice and easy to see into the tank if it is less that 1/4 full

Cheers,

wooa

  • 2 weeks later...

anyone know where i can get a tomei fuel pump from? and also how much it would be?

if someone does can you please pm me

thanx :)

edit just found one on nengun for nearly 400 delivered. Is there any other companys out there that are cheaper?

Edited by MMM

OK, Ive done mine too and took heaps of photos 'cause i thought these ones went missing and now they're back !

Oh well.... here you go anyway.

Hope it helps someone.

And i did install the little valve thingo, might aswell. Only took 2 mins :sorcerer:

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post-5823-1176950777.jpgpost-5823-1176950800.jpg

post-5823-1176950830.jpgpost-5823-1176950854.jpg

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Edited by Birnie

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