Fuel Pump Direct Feed Rewire.

[Guilt-Toy]

I have an R33 and im sure my pump is doing the same thing - but then i was told that the voltage will increase as the engine loads up so there is no need in wiring the pump direct to 13v

whats the advantages of doing this ? ive go a walbro 255L ph

[Sydneykid]

I have an R33 and im sure my pump is doing the same thing - but then i was told that the voltage will increase as the engine loads up so there is no need in wiring the pump direct to 13v

whats the advantages of doing this ?  ive go a  walbro 255L ph

<{POST_SNAPBACK}>

Whoever told you that only gave you half the story, as usual. R33's run lower voltage at idle, so the fuel pump doesn't keeping pumping excessive fuel around and heating it up needlessly in the engine bay. They revert to normal voltage above idle, that's the problem, the standard wiring limits the "normal" voltage.

The Walbro 255 lph pump only pumps 255 lph at 13.8 volts, at 12 volts it pumps ~210 lph and at 11 volts ~190 lph. The usual voltage at the pump we see is 11.2 volts when the standard wiring is used. That's at full rpm, max charge from the alternator and nothing else other than the engine running (eg; no aircon, no stereo). Plenty of other report the same, do a search for more details.

So if you are still using the standard fuel pump wiring you paid for a 255 lph pump and your are only getting ~190 lph out of it.

cheers

[benl1981]

Sydneykid - Is this direct wire worthwhile doing to a standard pump in an R33? Or could it burn it out quicker.

I have an R33gtst that I'm waiting to get tuned with a few mods..hoping for about 190rwkw. If I do the mod after the tune could it stuff the tune?

I wouldn't need any extra devices like what you were talking about would I?

Edited November 21, 2005 by benl1981

[Tangles]

Its not an expensive mod, having it done today at Graham West workshops...... best to get it done before the tune.

[benl1981]

Do I need anything extra done? Just add a fuse I guess. Are there any side effects?

Yeah might do it before the tune

[Cubes]

bwilkeson,

You previously mentioned...

high pressure fuel lines

You mean high flow fuel lines as in larger diameter?

How much is he charging for the wiring? Out of curiosity

Quickly ring him and ask to fit up a switch to disable the fuel pump(s) should you need to work on the the fuel system. Also aids as a kill switch should you be required to leave the car in a shady area.

I went a little silly on the fuses etc I used.. The 'mod' ended up costing me close to $60.

Edited November 22, 2005 by Cubes

[Tangles]

I'll get back to you Cubes once Ive got the itemised invoice, just got a total rough quote for a whole lot of work......

[Cubes]

I edited my prior post..

[benl1981]

What about in the case of an accident? Usually if you switch iginition off fuel pump will stop. Should you have to wire in so it is ignition switched? Did you do that Cubes? I guess you would have had to otherwise pump would be on all the time..Ill read the post agin later to see if it outlines this...

[Tangles]

Cubes, getting Ashley to wire the direct feed coming thru the engine bay fuse box, there will be a fuse installed there that I can simply take out, if I so wish, to disable the fuel pump.

High pressure fuel lines will be used due to the extra boost (say 15psi) that will be run with the hiflow turbo next year, and also for the 10psi extra pressure that is possible with the Nismo F.P.R. Thats and extra 25psi being used over what they were designed for. Its a recommendation from SK, so I thought I should take him up on his advice.

[Cubes]

Ben,

Which is why you wire it via a relay. Check out the first page part listing.

bwilkeson,

I've replaced all my fuel hose, pirtek have some good solid hose clamps to suit, much better than the cheap ones you get from the usual auto store. Fuel hose was damn expensive cost me $13 a metre for the good stuff.

[benl1981]

Can I wire it to the standard relay? Im an R33 so battery is in the boot. Do you use the original wiring to trigger the relay

Thanks Cubes! I'm not going to strain my old pump am I?

[Tangles]

Thanks for the advice, Cubes, with the 'switch', thats a good idea.

Im thinking its just high pressure fuel lines & stuff, not larger diameter for increased flow.

Only after around 200awkw with the hiflow turbo next year, expecting around 160awkw with this weeks mod efforts. For 200awkw I dont see the need for big diameter fuel lines, its not as if the Stagea is a 260RS (yet!!)

Brendan

Edited November 22, 2005 by bwilkeson

[Cubes]

Can I wire it to the standard relay?  Im an R33 so battery is in the boot. Do you use the original wiring to trigger the relay

Thanks Cubes!  I'm not going to strain my old pump am I?

<{POST_SNAPBACK}>

I bypassed the std relay. It could be done, its much simpler to simply run a direct feed from the battery in to the boot, run it through the fuse then in to the relay. Use the existing std pump volt feed as the trigger. Be sure to mount the relay up and down.

Since I mounted the relay vertical instead of sideways it hasn't jammed on. YET!

It won't strain the std pump, they are designed for that voltage.

Edited November 22, 2005 by Cubes

[benl1981]

Nice one Cubes. Thanks a lot. So I guess I will buy a relay, does it really matter how you mount it? Run an earth line to pump aswell you think? Do you think connect it straight to that battery terminals?

Maybe I will do it before the tune so I don't risk getting there and it running out of fueling..

[Cubes]

I ran an 8GA cable from the battery + to the fuse, to the relay, then 8ga from the relay to the external fuel pump and splice in the interal fuel pump.

I ran a nice 8GA earth from the fuel pump to the chassis for the earth. One again splicing the internal fuel pump into the earth.

Mount the relay vertical. It has appeared to stop mine from sticking on every blue moon when cold. I will replace it to be safe.

Edited November 22, 2005 by Cubes

[benl1981]

If the relay fails closed you could get a potentially engine damaging event occuring right...Or you'll just get fuel cut? Only momentarilly lean?

[benl1981]

I wont get excessive fuel flow at idle will I - that heats up the pressure? I have standard R33 pump. SK was talking about other devices to stop this. Are they unnecessary?

[Cubes]

If the relay fails the engine will stall.

Its the same if the std relay were to fail.

Either that or as some one previously mentioned the relay will fuse preventing the fuel pump from turning off when you turn the car off.

Edited November 22, 2005 by Cubes

[Cubes]

I think the high/low is really unnecessary. It would be nice to have but it still didn't stop the fuel heating up and making horrible sounds with my external pump when I was running the stock ecu.

If anything, now with the pump receiving the voltage it should the pump is quieter.