Fuel Pump & Injectors
Upgrade the Fuel Pump
At the very minimum, a 255lph fuel pump is required, Walbro makes a nice unit that sells for half the price of a new OEM pump cost. Installation of replacing the fuel pump process is quite straight forward and well documented on forums and Youtube.
There is a common problem among these vehicles of the connector plug for the fuel pump and sending unit shorting out inside due to corrosion. Its recommended to remove this connector and solder the wiring direct connect to eliminate future problems.
Walbro High Pressure 255LPH Fuel Pump
Fuel pump & install Kit – PN# GSS341/GSS341/GSS340 Install Kit – 400-739.
Supports up to 500 Horse Power.
Optional Adjustable Fuel Pressure Regulator (AFPR)
This isnt required but can be handy to dial in your injectors or increase pressure to reduce duty cycle. An adjustable fuel pressure regulator will allow you to raise the base fuel pressure reducing the duty cycle of the injectors- ultimately allowing for higher boost with out maxing out the injectors. Its recommended not to raise the base pressure 20% over stock pressure to limit stress on the fuel pump. Should your setup require more then a 20% increase, larger injectors would be required.
The standard AFPR that you will need is anthing for EFI rated that is adjustable from 0-100psi. Many regulators are adjustable from 30-70psi and this will work just fine.
The Stock Fuel Pressure for a KL V6 Engine is 44psi.
Fuel rail adapter
Should you add an aftermarket fuel pressure regulator, you may need a fuel rail adapter, these are becoming increasingly more uncommon to find and the next viable option is using a 1/4NPT Tap to thread the outlet for the stock fuel pressure regulator on the fuel rail.
This isnt required, but it a nice upgrade if your planning some big power. The stock setup is a series setup, the injectors are fed from the rear bank to the front bank and returned to the tank. In theory, the front bank injectors could lean out in a high output situation as the rear bank is pulling fuel first. However, this may just be theory, as the regulator sets a consistent fuel pressure that pressurizes both rails at all times.
The dual feed setup will send divert the fuel equally between the fuel rails, thus eliminating a risk of fuel starving on the front bank.
Below is a diagram of how this is setup along with part numbers to popular fittings needed.
The below picture links to our How To Guide that illustrates the plumbing for single and dual feed setups, along with a list of the required parts to build your AFPR setup.
King6fab has now developed and is providing options regarding Nissan side feed injectors. Currently on the King6 Turbo Mx6, we are using Nissan yellow top side feed injectors, rated at 555cc. The required fuel value for these is 5.0, and currently duty cycles are 40% at 43psi fuel rail pressure and 8psi of boost un-tuned. We estimate that they will be good up to 16psi of boost.
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Select options This product has multiple variants. The options may be chosen on the product pageAll Products, Fuel Injectors, Fuel Injectors, Fuel Injectors
Nissan Bored Fuel Rails Service
Nissan Bored Fuel Rails Service
$275.00 – $300.00 -
Select options This product has multiple variants. The options may be chosen on the product pageAll Products, Fuel Injectors, Fuel Injectors, Fuel Injectors, Turbocharging, Turbocharging, Turbocharging
Nissan Injector Fuel Rails Completed Package
Nissan Injector Fuel Rails Completed Package
$240.00 – $405.00
Additionally if your handy in a machine shop we have a how to for boring injector rails your self for Nissan Injectors. See the Nissan Injectors How to for fuel rail modifications needed.
Upgrade the Injectors
The stock KL Injectors of all KL Motors are 220cc, this is good for about 2-3lbs of boost at max. You can cheat this by raising the fuel pressure, but your limited by the fuel pressures expressed earlier.
You can find Millennia S injectors anywhere from forums to eBay, they are estimated to be 280-300cc. They range from $150 or less. If you choose to use Millennia S Injectors, you will need to change the required fuel to 10.0 in the Engine Constants in Tuner Studio.
Finding The Injectors- They look the same as the OEM blue top injectors you have now, but they will be a purple/pink top instead. They can be used in your factory rails. Millennia S injectors have been known to used up to 10psi of boost, however in most cases they are maxing out duty cycle 100% around 8-9psi boost as 55psi fuel pressure. There are other options for fuel injectors such as Rx7 Injectors, witch are direct drop in but expensive and hard to find 6. A Duty cycle of over 80% is damaging to the injectors and there is risk of the injectors staying open or not opening at all.