damnonrs

finally fixed this issue and was able to get my 2.8 fully tuned, the car is an animal now! pretty much the issue was a bad fuel pump relay 😆, hence the fuel pump pressure dropping with load

so i spoke to my tuner, and he said he just changed the wiring that goes from the battery to the pump, the line in the fuel tank and the wiring in the fuel tank is still OEM at like 22 gauge or whatever it is. is that essential to upgrade or would that restrict the voltage?

i will hard wire it for now until my problems are resolved and get it dyno tuned again. i'm just worried about fuel temperature running the pump at 100%, is that a problem or its ok to just have it on full blast at all times

is there any write ups on doing this for the 34 gtr? i know 33 and 32 are different

Awesome, I’ll look into this on Monday. Thank you for your feedback so far!

What’s a fpcm? this is what the fuel pressure does plugging it in and out. It raises when you unplug it IMG_7522.MOV

I will check again tomorrow, could I have a pretty bad vacuum leak somewhere in the surge tank or something

It’s plumbed like this

Yea that’s exactly it, and yes the fuel pressure goes up like I said earlier when I remove the vac line

Dampener is after the fuel pressure regulator on the rb26, removing the vac line changes the idling by like 0.05 bar or something like that If it satisfies you I also ran the car with the hose right off the fuel pressure regulator as stated and nothing changed

So I dove into the fuel system today, I removed the line coming out of the damper and plugged it into a fuel canister. The idling pressure dropped from 4.25 idling to 4.05 steady. I’m assuming the 5% improvement is because of all the twists and turns tk get back to the fuel tank. So damper isn’t the problem. But then I also tried plugging it straight from the regulator and it was the same thing. All that’s left to test now is regulator itself or the rail… which brings me to: do I buy a radium fuel rail with damper and fuel pressure regulator in one? Also check this out. When I rev the car the pressure just goes to 3.5 and jumps back to 4.2 I posted a video IMG_7513.MOV

thanks for pointing that out, its what ive been thinking too. looking at the service manual it says this how can i test my fuel pressure regulator? or even check that its being blocked? are the return lines mostly all visible? should i just pinch the lines? from what i understand its two lines running under the driver seat all the way to the tank, one feed one return. rail blockage do i just take a peak in there and hope i see gunk? just kinda thinking out loud since i visually inspected and didnt see anything wrong. should i even bother with the damper thing..? thinking back the tuner threw on a AEM fuel pressure regulator on the dyno and it was still leaning out up top. he never mentioned to me if my idle fuel pressure was still high. thanks!

Oem r34 gtr fuel lines are good for well over 1000hp. I’m assuming the nismo fpr should work as all I need it to do is just set a target of 3 bar. right now my car idles at 4.11bar with a stock fuel pressure regulator somehow does the pump hanger need modding to fit?

Okay okay, I still find it weird a 044 is peaking at 400rwhp but i have a new plan which will most likely work and worst case power through my problem. if I buy a nismo fuel pressure regulator I can set the idle fuel pressure to what I want and not go over the 3 bar idle standard for the rb28 (I’m assuming a 2.8 is the same fuel pressure) and from there I will upgrade to dual very high flowing fuel pumps so I can just run e85 anyways. with that being said what do you guys recommend in terms of installing a dual pump and which pumps? Thanks

Okay got it, before I dive that deep i want to check something, Is there anyway to find a full fuel line diagram? That goes from the pump to the regulator. Return line included ive searched but can’t find anything