Carloverx

iTrader: (26)

Correct me if I’m wrong but…

The Evo has THREE fuel pump relays and ONE resistor.

Relay 3 controls whether the fuel pump power goes through the resistor or not. People rewire their pumps (directly from the battery to the pump) because even off the resistor, the voltage is low.

PROBLEM:

The higher voltage of a rewire, ends up over running the stock FPR with bigger pumps (dw301).

SOLUTION:

A. I am going to have a Relay 4 which will be triggered by Relay 3.
If triggered, Relay 4 will have power coming directly from the battery, and go directly to the pump (like a rewire).

B. If Relay 3 is NOT tripping Relay 4, it will be using the STOCK wiring which runs through Relay 3 and the stock resistor. When the ECU is asking Relay 3 to skip the resistor, it will end up tripping Relay 4 and get direct signal.

C. Most double pumpers and rewired DW301 pump setups require either an AFRP or a hobbs switch setup because the duel pumps or direct wiring will overrun the stock FPR.

QUESTION 1:

Why are people running hobbs switches when they could simply add an additional relay which is triggered by the stock ECU to go to a direct signal when the car needs it


QUESTION 2:

What ECU parameter is triggering Relay 3? And is it adjustable


Please answer with a SINGLE fuel pump setup in mind. And no, I'm not simply purchasing an AFPR lol.

Thanks in advance.

Carloverx

iTrader: (26)

Hmmmm:

https://www.evolutionm.net/forums/9588866-post472.html

Not a good sign if mrfred isn't sure:

mrfred

iTrader: (50)

i know its triggered by load. just haven't found the control subroutine yet. just a matter of making time to figure it out.

andrewzaragoza

iTrader: (6)

it will be good if this will work rather than getting a afpr.

03whitegsr

iTrader: (8)

The fuel pump goes full power under everything but idel and decel conditions, from what I have logged. I'll have too look again, but I think I found the section of code that controls it in 9653XXX6 as well.

mrfred

iTrader: (50)

Address?

Carloverx

iTrader: (26)

Interesting.

I should have the car wired up in a few days. I plan on running a light into the cockpit to get an idea of what it takes to trigger relay 3.

I hope "anything off idle" will consume enough fuel to keep the stock fpr from being overrun.

03whitegsr

iTrader: (8)

Here is the specific post.
https://www.evolutionm.net/forums/9288748-post73.html

Here is the thread.
https://www.evolutionm.net/forums/ec...p-control.html

I have not verified that it is in fact the fuel pump. I logged the car long ago and looking at MUT9B bit.0 on acamus recommendation, as he felt it controlled the fuel pump. Those addresses control that bit.

Carloverx

iTrader: (26)

Check out my video. Make sure to turn up the sound to follow along with RPMs. Green LED shows when relay 3 is shutting off, and thus circumventing the resistor. It looks like using this relay to control direct-battery-voltage to a large pump to avoid over powering the stock fpr can be an easy reality. No hobbs switches. Thoughts?

http://www.youtube.com/watch?v=Qszwg8dwRz0



EDIT: here're the answers https://www.evolutionm.net/forums/ec...p-control.html

sparky

iTrader: (1)

EDIT: See post eleven below.

sparky

iTrader: (1)

I realize that a Hobbes switch is considered to be a cheap and flimsy trigger. Having said that, I like the simplicity and ease of adjustability of a Hobbes switch in a turbocharged application. Boost triggered secondary pumps are where its at as far as i am concerned.

I said that they are cheap devices but I happily coexisted with one on my Turbo Buick's ATR staged double pumper with dual Wallys for 50,000 miles of hard driving and never a glitch. I went through four or five replacement pumps( as well as two wives)....but that little five dollar Hobbes never gave me a problem.

Incidentally, how would you go about adjusting the activation point of the secondary pump if you were to use that factory relay in the way that you have just described to us?

mrfred

iTrader: (50)

I'm in the process of doing a rewire that utilizes the controller pin on the ECU for fuel pump relay #3 to provide high/low voltage with a pump rewire. Its a bit more complicated than the typical rewire, but not bad. Total parts cost for all the wiring and relays is probably going to be about $50. I'm hoping I can finish it today and test it out, but most likely, its not going to be done until I get back from vacation around January 1.

Carloverx

iTrader: (26)

My setup is done. I'm using a DW301 rewired. Two extra relays, one to turn on the direct battery source when relay 3 turns off, and one to power off that relay when the car is off (this way the pump doesn't get power when the car is off).

Runs and drives perfect. Haven't tried it at high HP, but shouldn't make a difference.

mrfred

iTrader: (50)

Sounds like you are doing it a bit differently than what I am doing. I only use two relays total. When you get a chance, please post the wiring diagram that you used.

fre

iTrader: (4)

My application is slightly different (AEM), but I trigger my second fuel pump based on throttle position and load off the AEM. I would guess the stock ecu does something similar.