What about the IATs? Did they change? Nowadays the weather changes about 30 degrees from night to mid day. I am sure SC is more stable. I would adjust for the new logs and continue to monitor. IPW is pretty set so it shouldn't have affected it at all. Could be an anomaly.

 

I understood that you didn't have to rewire the pump because there are 3 relays to power the pump at different loads. Kind of like a speed control. This is very common for DSM's to rewire the pump.. I haven't really heard about it for the Evos thou. As far as the wiring diagram. I have no idea what I’m looking at. I wish I could help you. And If you only going lean .3 AFR.. I won’t be worried. The sensor could just be getting old or other factors could affect the AFR...

 

with the factory wiring and 3 relays, the pump only uses 1 relay with a resistor to control a 2 steped voltage. the other 2 relays are used for other purposes.

Relay 1 is used to kill voltage with the key, comes on with the key.

Relay 2 is used for ECU contol kill switch, like if it doesnt get the signal of oil presure the ECU will not ground relay 2, causing the pump not to work

Relay 3 is used to control the actual voltage for the pump. The ECU also controls this ground. When not grounded, the voltage flows thru the resistor for low load voltage, when relay is grounded, the voltage flow directly thru the relay for high load voltage.

What I have done by doing the hotwire in either form (see diagrams #2 & 3) is to cause direct battery voltage (14.4+) to the pump, but still using the kill switching ability of the ignition switch AND the ECU incase it deems necissary to do so. the problem I am running into, IMOP, and why I posted is; If by using the diagram #2, using the factory relay 3 to supply the power to close my "new relay," would it be causing a feed back/irregularity when the ECU switches from low load to high load. Would it cause my to loose my full 14.4v at high loads when the ECU switches to high load?

 

Back from the dead....
I have been searching for an answer to this as well.

 

Put a voltmeter directly on the wires to the pump, make a pull and watch the voltage. We can sit here and speculate all night, but that's a quick and easy op's check. Then, after that, do the same thing on the wires that close the relay.

 

Well i got bored last night and decided to check voltage at the pump at idle. It only came out to 6.8-7v and i had my aeromotive afpr adjusted to 38psi(gauge on fpr) with the vac hose connected. Only thing i have done electric wise was move the battery to the trunk and ran 0ga wire all the way. Anybody know what would cause the low voltage?
After, I rewired the fuel pump with a 30a relay and ran a 10ga from the battery. Now voltage at idle is 14.4-14.7v and my fuel pressure is 48-50ish, with the vac hose connected.
So for anyone running any aftermarket fuel pump (i presonally have two aeromotives in a double pumper setup), i recommend rewiring your fuel pump.

-Jesse

 

Lolz, This thread could be a zombie its so old!


jessmanEVO, I would run a dedicated new relay for your fuel pump needs. Run a 10 gauge, like you have, fused from the battery to the pump, and just before the pump run a heavy duty relay with the factory fuel pump power supply wire as the signal wire for the new relay. I would also bypass the factory resistor relay and resistor itself.

 

Now would the resistor pack happen to be on the firewall by the #3 and electric pump relay? If not, where/how did you disable yours?

 

Let me think and look about on this one. I actually sold my evo a few years back. Im rocking a Z06 now. I will get back to you shortly.

 

ok, so find the abs pump. on the firewall to the right of it, there is a wire connector. to the right of that is a relay. that is the fuel pump relay 3 (the one that switches voltage and should be removed if doing a proper hotwire) directly below that relay is the resistor.

To by pass both the relay and resistor, you would disconnect and removed the relay 3, and jump the pins to pass thru the harness. [I normally assume people know how to find the pins for a relay, but just incase]

Take a test light and connect it to the battery negitive post. Taking the probe side of the test light, and probing the back side of the relay connector (with the relay removed, and the key in the on position) check each of the 4 wires to find the power signal from the vehicle to the relay. The test light should light up with the key on, and turn the light out with the key off. NOTE this pin. SWITCH the test light connector on the battery from negitive to the positive terminal. Now repeat probing the rear of the connector, skipping the pin that you previously noted. When the tester lights up, you have found your ground pin.

Now jump those 2 pins and you have now bypassed the relay and the resistor. Use this circuit to turn on and off the new heavy duty relay at the fuel pump module for the 10 gauge wire for the hotpump.

 

Thanks a lot Sabastian. I'm currently running around with the relay and resistor still on. I'll get around to it once i have time. Would I damage anything if I don't bypass the resistor and relay?

 

I wouldn't think it will damage anything, it would just reduce the signal voltage for the new heavy duty relay.

 

sabastian did you ever figure out why you were running leaner? I think that's key here. I've rewired mine and definitely seen an increase in fuel pressure but I'm still curious as to the leaner issue.

Thanks for keeping up with this thread after so long

 

Honestly I dont think I did. I forgot about this thread until it was resurected. I am still willing to help others with questions about this tho.

I contribute the leaner condition to possibly heating the fuel up or overflowing the regulator at idle and causing it to be weaker. (it was a stock 60k mile regulator)

 

If you do rewire it, and youve got an AFPR, I recommend a retune.