More fun with Fuel Systems...

[UK_SPAWN]

Hi,

Yet more information is needed for me to part with my money, Take a look at the Diagrams below:

Does everything look ok??
Where i have the switch installed etc?


http://img508.imageshack.us/img508/1...psetup1qq2.jpg


http://img381.imageshack.us/img381/5498/relay1wh1.jpg


And the Fuel lines?

http://img377.imageshack.us/img377/8...psetup2ty9.jpg


Also, is a relay necessary if I'm using a switch? I cant see why it is? a relay is just a switch?


Thanks for the help as allays everyone .

Mark

[Listerofsmeg]

why would you use a switch anyway?

nice rendering by the way.....

[DRAGON]

How long did that take you!!! Just use the standard power to the intank pump to trigger the relay, unless you want the switch for some reason?

[UK_SPAWN]

anti theft , and also to eliminate the pump controller, and make everything very easy too visualise and replace...

people seem to think its bad? but i dont see the difference, turns the power to the pump on and off???

[UK_SPAWN]

yes someone suggested i use the original ECU wire as the trigger.. but that means a long crappy thin piece of cable running from the foot well to the boot... why not have a little switch down near the handbreak somewhere (closer to the boot) ,and because its all made by me, the wire gauge can be large enough to accommodate for voltage drops.

Make sence.. Plus if a thief trys to steal your car, they have no fuel.

[UK_SPAWN]

LOL and the moddeling took me about a day .. just starting to get back into it thnx for comments

[Listerofsmeg]

unless they know about the switch

i didnt have to have a long cable run from the footwell on my set up....the standard fuel pump has a permenant live feed somewhere in the loom that it was tee-d in to.

The used a relay per pump (as i have 2 extra ones), then pretty much as you have it....

Would you locate the switch in the boot? or mount it somewhere in the cabin?

[UK_SPAWN]

down near the handbreak , slightly concealed but not out of the way
.. so anyone that dosent know the car, will not know how to enable the pumps.

I have a removable steering wheel too, for anti theft. i dont think alarms work nowadays, you have to be more cunning.

Anyway, i could just run (+)Posotive wire from the pump straight to the battery, and have a switch on the earth , inside the cabin like i say, this gets rid of the relay, and aslong as i use an inline fuse, should still be safe.

[frostmotorsport]

Originally Posted by UK_SPAWN

Also, is a relay necessary if I'm using a switch? I cant see why it is? a relay is just a switch?

a relay is a high-current capability switch - so if you tried to switch the pump feed from the cabin, you'd get massive current drop due to the length of cable and you'd need a frickin heavy duty switch, which would struggle most likely!!

your wiring and fuel lines look spot on to me (and nice renderings - beats my MS Paint efforts!)

I'd use the ECU - remember that you only need to tap off the wiring behind the rear seat, not run wires all teh way from the ECU itself - it's already part of the loom - for mine I simply pared back the insulation, soldered my relay wire to it and wrapped with insulation tape - for a better look you could cut the wire and heat-shrink!

The nice thing about the ECU switching the pump is that you don't have to remember to turn it off/on - and your seperate switch is just a security feature.

Remember to solder ALL your joints - crimped joints cannot carry the current a pump deserves - and plan all your wiring runs to keep lengths to a minimum - and I always use wire a few grades up from whats' required so current capacity is never an issue!

[Abbey M/S]

having the ECU controlling the fuel is for safety , if you have major shunt and the way you want to wire you car the engine can stop running but the fuel pump can still pump , this could if a pipe fractures pump out, neat petrol which could start a fire.

If you want to fit a imobiliser switch just cut the trigger from the ECU to the fuel pump control module , use a relay that switches the earth to keep it nice and tidy.


mark

[UK_SPAWN]

Okay got it,

So just where i have the switch, i use the original ECU earth,
but what about the pump control unit thingy... can i / How do i disable that? so the relay signal is at a constant voltage and not modified by the unit.. or is it not neccecary as it is just switching the relay, and not powering the pump its self any more?

Thanks.

One more thing, when i install this new pump, directly to the battery, will i have to modify my fuel pressure at all?
What should my fuel pressure be? im not sure on this , but its somthing to do with manifold pressure and boost?
well, im running 1.4bar boost, how do i calculate it ?

Is bar relative to KPA , like err, is 500kps 5 bar?

Thanks all,

[Abbey M/S]

So just where i have the switch, i use the original ECU earth,
but what about the pump control unit thingy... can i / How do i disable that? so the relay signal is at a constant voltage and not modified by the unit.. or is it not neccecary as it is just switching the relay, and not powering the pump its self any more?

TBH 100% honest from what you have written above I dont think you understand how a re fuel system works and hows the fuel pump voltage regulator works.

Let me exlpain again;

1, you can use a relay which you supply a voltage feed from a ignition live to make/brake the feed pump feed wire , you switch the relay by a switch which goes to earth when turned on. when you turn the switch off the relay will not work so the fuel pump will not feed fuel to the engine

2, the Nissan fuel pump regulator works by supplying a varing amount of voltage down the earth wire to the fuel pump. The cars fuel pump relay which is triggered by the ECU which you are going to add another relay to provide a cut out switch feeds 12volts direct to the fuel pump. when the car is idling approx 6 volts is feed down the earth wire so running the pump at approx half speed the fuel pressure will be the same just the volume will be lower.

You can cut the "earth" wire to the fuel pump ( this wire is shielded) and the wire that comes from the pump, earth to the body of the car , this will run the pump @ battery voltage.

For you spec of car bypassing the voltage regularor and fitting a 280 ltr/hour pump will be plenty good enough.

Re the fuel prresure again I dont think you understand, the std fuel pressure for a RB26 is 3 bar with no vaccum ,remove the vaccum pipe to the fuel pressure reg and adjsut the fuel pressure to 3bar if you have a adjustable reg. I would ask Peter if he run at 3 bar fuel pressure because a lot of people ekk up the fuel pressure to get more output from a set of injectors , like running a set of 600cc @ 4 bar static will allow you to run more than 600bhp.

I am of the opinon the 1cc for 1bhp is not correct , to many variables, fuel pressure , fuel oxygen content. all make a difference.

Hope this helps , sorry if I come over a liitle rude, just dont want you blowing your motor up.


Mark

[UK_SPAWN]

not rude atall, there is an adjustable FPR on there, and i think im going to get a meter. i think peter ran standard fuel pressure , they are 660cc injectors , i have not adjested it, but i think a tow truck guy did, but he asured me he put it back. anyway...

you say, remove the vacume pipe on the REG and set at 3.0bar, how would i know when its there? im guessing i need a guage.

What are the risks, say if its half a turn too much one way?
It "looks" in the same place its allways been at.. but thats why i want a pressure meter.

So to clarify fuel pressure should be 3.0bar .

[frostmotorsport]

Mark is correct (though the regulator varies resistance in the earth rather than feeding it voltage!!!) - however, our friend Spawn intends to use the factory pump as a lift pump to the swirl-pot - so I would bypass the regulator for that so the lift pump is running full bore. noise won't be an issue with an external pump in the boot drowning out all other noises!!

Regarding fuel pressure, I wouldn't think changing pumps requries a change in pressure itself - however, you could adjust pressure as Mark says if your tune requires it.

[Abbey M/S]

1/2 turn to much is just a rich mixture and a few less BHP 1/2 turn less can be a melted motor.......

Static STD pressure is 3 bar , try measuring it before doing your mods. Ask peter what he ran his car at , fuel pressure regs do fail.

Again are you 100% confident , you your playing with can cause you to melt a motor.