Forum » General Tuning Discussion » Sporadically low fuel pressure

Sporadically low fuel pressure

General Tuning Discussion

Discuss all things tuning in this section. News, products, problems and results. 


Page 1
Author
83 Views

Hey guys as the topic suggests I've been having low fuel pressure on my car. I'm in the US and I have a gtr swapped Nissan 240sx. My fueling system is like this; dual AEM fuel pump in tank to a stainless steel y pipe to 8an nylon braided line to a radium fuel rail. The return is a 6an to tomei fuel pressure regulator to flex fuel sensor and the 6an nylon braided line all the way to the tank. The power supply to the pumps are as follows, I've used the wire from the fuel pump relay as a trigger for another relay that has two 12 guage power wires to each pump being supplied in turn by a 10 guage from battery terminal. I've noticed that during ordinary drive or moderate boost 11psi, the car is ok, however if I attempt keep opening the throttle I'll get a violent jerk which I'm trying to figure out if it's boost cut. Looking at the data log the low pressure spots are somewhat random, I've seen spots where it's a 0% throttle opening I've seen them at 40%, any suggestions would be welcome. I'm running the haltech platinum pro and the engine harness is brand new also. I'll post a picture of the fuel pump wiring setup and the engine bay. I don't think it's battery related because it's happening when the battery voltage is at 13.6 volts. Tune is in alpha n. I have the R35 coils and I also changed to iridium ix and I'm still having the same problems. Coil wires were also changed with no positive outcome.

Attached Files

A violent jerk sounds more to me like you're getting a cut rather than a fuel pressure issue. It's hard to say without seeing some data. Is the cutting something you can reproduce every time under the same conditions? How much are you seeing the fuel pressure fluctuate? One thing we've found with upgraded fuel systems that retain the stock tank and no surge tank is that they will often surge badly under hard cornering even when you still have perhaps 1/4-1/3 of a tank of gas left. If you can replicate this issue with a full tank then this really eliminates that as a possibility though.

Hey Andre, happy new year to you, thanks for the response. I've searched through all the settings in my tune and I cannot find where I could be getting the cut. The only thing I've noticed was I had a loose clamp on one of the fuel pump hose in tank I've not been able to make another street run since, as soon as I have done so I'll post the log. I'll upload some pics of the low pressure events I had prior to finding the in tank pump issue.

Attached Files