Aux output to fuel pump

[4g63evo]

I've 2 fuel pumps and I want to stage the 2nd one, as my fuel system is creating too much pressure whilst my FPR is wide open.

A bosch pressure sensor is on the fuel rail to monitor pressures.

I want the ecu to turn on the 2nd fuel pump when fuel pressures drop below a certain point.

Can AUX 11 on evolink g4+ achieve this?

Would the attached wiring diagram work?

[koracing]

That should work, but technically 85 should be the ground trigger and 86 the positive trigger.  Personally I remember this as 86 is slightly more positive than 85.

[Adamw]

And to confirm, Aux 11 set as a GP Output can be switched based on fuel press.  Personally I would use inj DC to switch it rather than pressure, you dont really want to wait until pressure drops before you take action.  Injector duty cycle is much closer related to how much fuel flow is required.   

[4g63evo]

Great. Thanks guys, I'll give this a go and use injector dc

[4g63evo]

After a bit of research, the stock Evo wiring should be running the fuel pumps at a slower speed when at low load and engaging fuel pump relay 3 at high load. Is load RPM based or based off the stock fuel pressure regulator?

I’ve deleted the stock fuel pressure regulator due to an aftermarket intake manifold and installed an aftermarket fuel pressure regulator but can’t seem to get the pressure down whilst idling
 

 

[k4nnon]

Hey just a little input on this, First off what fuel pumps and what pump hanger are you using? And I assume you are using a larger fuel feed and return line kit? In most cases it is advised to just run the aftermarket pumps hardwired via a relay. Makes it easy, just take the normal fuel pump power wire from the existing wiring and use that as the trigger for the relay to kick on the pump. This will be running at 13-14v constant. As far as the second pump goes, it is very easy to send a trigger signal from link to activate another relay to kick on the second pump. You can do this with a power signal or a grounded signal. I prefer sending ground as often as I can.  As far as your pressure stuff goes, Your fuel pressure should never drop much below your base set point. If it is dropping then there is then there is an issue somewhere else or maybe the second pump needs to kick on earlier to keep pressures in check. Now depending on your pump and hanger setup, it may have a stock or aftermarket fuel siphon provided by the manufacturer. If its a stock siphon it either will or will not need drilled out. A lot of companies will sell a dual fuel pump hanger with a siphon that has already been drilled out to the correct size. This is a major part in keeping fuel pressure where it needs to be especially with big pumps. Also some fuel pressure regulators will have different internal parts that you can change to help regulate fuel volume. Should be pretty easy to get your pressures in check. Stick to a base pressure of 43.5. Hope any of that helps.

[4g63evo]

I'm running dual walbro 460's radium hanger -8an feed, -6an return.

They're currently both hardwired on the same oem fuel pump wire trigger. This would mean the both pumps run at 13-14v constant and creating too much pressure. (I have a new FPR otw to try and bypass more fuel)

I've done a bit more research and;

I can have 1 pump hardwired to the oem fuel pump to run at 13-14v constant and the 2nd pump hardwired to a link aux output to run the 2nd pump at 13-14v constant when injector dc rises.

Or I can hardwire both pumps at 10v at low load and 13-14v high load. Does the link ecu have tables I can edit to control the oem fuel pump relays? At certain loads / rpm's? I thought this would be an advantage as it will allow the pumps to run less power / cooler at idle / low load?

 

[k4nnon]

Yeah you dont need both pumps running at the same time, That will increase fuel temp too much as well as make your pressure hard to deal with. Iv made over 700wheel with a single hardwired 450 in my evo 9. So there is no need for both pumps to be running at idle or even low power conditions. Iv installed many radium units and they do have their own fuel siphon design so there shouldnt be any pressure created by not enough fuel being returned. Im gonna say your main issue is having both pumps running at the same time when they arent needed. Just run one pump through one relay triggered by the factory pump power wire, then trigger your second pump with link to come on at like 15-20psi or wherever you feel its needed. 

Another thing is that the walbro pumps werent really designed to operate less than 12-13v so there is a higher risk of pump failure operating them at lower than intended voltage.