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Posted

When I had my R32, I rewired the fuel pump to have full power all the time.

Also what kind of fuel pressure setup are you running? Possible too much base fuel pressure and its not adding more pressure on boost? Ie dodgy vac/boost reference.

Any differences in fuel line sizing between cars? 

Posted
48 minutes ago, shrike said:

When I had my R32, I rewired the fuel pump to have full power all the time.

Also what kind of fuel pressure setup are you running? Possible too much base fuel pressure and its not adding more pressure on boost? Ie dodgy vac/boost reference.

Any differences in fuel line sizing between cars? 

initially i had the pump hotwired to 12v because the alarm was being a dick. it did not like that one bit.

the vac reference for the pressure reg is coming off the factory vac port and I've tried two different fuel pressure regs, ive also confirmed that the gauge is reading fairly close to right. 

fuel line is the same between both cars. pumps are different. pump in my car is a high flow unit of some sort. however flow does not equal pressure so i cant see how different pumps delivering the same pressure at the rail would make any difference. 

  • Like 1
Posted

Similar to @shrike suggestion my old evo had an idle voltage supply for the fuel pump presumably to reduce noise, and then a second relay when the engine was on a bit of boost. I fed it the full beans all the time by jumpering the relay that switched over to the full boost mode. Much easier to deal with when reflashing the ecu. 

Perhaps nissan has something similar?

 

edit:

 

As you were fine sir, must have been posting at the same time.

 

Double edit:

ecu is seeing less air when on boost than actually exists.  

So if its on a map sensor then start there.

Posted
1 hour ago, sheepers said:

initially i had the pump hotwired to 12v because the alarm was being a dick. it did not like that one bit.

the vac reference for the pressure reg is coming off the factory vac port and I've tried two different fuel pressure regs, ive also confirmed that the gauge is reading fairly close to right. 

fuel line is the same between both cars. pumps are different. pump in my car is a high flow unit of some sort. however flow does not equal pressure so i cant see how different pumps delivering the same pressure at the rail would make any difference. 

Whats the pump? 

I thought you would have ruled it out but what sprang to mind :) 

What ecu are you running? 

Any wiring changes between cars? or sensor changes? 

Not something silly like a sensor not plugged in easy to check if its an aftermarket ecu or wired backward? 

On the fake evo I had because I was running an RVR engine the TPS was wired backwards compared to the evo wiring so ecu thought throttle was closed at WOT and open at idle etc

Posted

What ecu are you running? I remember helping find a fault with this car when it had a powerFC. It had 2 map sensors and one had failed. 

Also, the factory fuel pump controller dicks about with the 0v return from the pump to change the speed. You want to ground the white wire coming from the fuel pump plug. It will still get its 12v supply from the ecu triggered fuel pump relay.

If your running the factory air flow meters, it sounds like you have an air leak between the turbos and the throttles. Maybe under the plenum. Something like the idle air controller hose or the brake booster hose

Posted
6 hours ago, fletch said:

What ecu are you running? I remember helping find a fault with this car when it had a powerFC. It had 2 map sensors and one had failed. 

Also, the factory fuel pump controller dicks about with the 0v return from the pump to change the speed. You want to ground the white wire coming from the fuel pump plug. It will still get its 12v supply from the ecu triggered fuel pump relay.

If your running the factory air flow meters, it sounds like you have an air leak between the turbos and the throttles. Maybe under the plenum. Something like the idle air controller hose or the brake booster hose

power FC.

i can run the fuel pump if i want to, thats not the issue. the issue is that the tune is setup for the idle fuel supply to be controlled by the fuel pump controller, which its not doing.

i have already pressurised the entire plenum and piping system looking for leaks and I'm fairly confident there are none. 

i spent another 4 hours on it last night with no progress.

i still have to go through the TPS and the idle switch wiring, that will be tonight's job. 

 

for clarity, the issue is that the fuel pump controller is either not turning the pump on at all, or its giving it 12v at idle, which then floods the motor. 

and the motor and ECU were running with no issues in the other car. the engine loom is different and the alarm has been wired in a very unusual and terrible way so im working my way through removing that.

i shall continue to battle with the fucking thing tonight. 

  • Like 3
Posted

Is the fuel pump controller pelresent in your car? It was probably bypassed and that's why it won't control. When the ecu turns the pump on, there is no low speed idle setting, it's just flat out.

 

Screenshot_20250708_181732_Gallery.thumb.jpg.a386e0c839d1c9479bef9333b09492f8.jpg

How good is your wiring diagram? I'll email you a good one that you can actually read the writing on.

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