In the 2004 model year, Nissan took the leap into the competitive, yet profitable full-size pickup market. Its entry was the 5.6-liter-powered Titan, and with a name like that, Nissan was certainly calling its shot. The 2006 Titan came equipped with the same 305-horsepower, 5.6-liter V-8 engine that its debut model had and this engine, just as all internal combustion engines, requires a specific amount of fuel pressure to operate correctly. Low fuel pressure can cause rough idle, misfiring, reduced power or may cause the vehicle not to run at all. Checking the fuel pressure requires a special gauge set and a fuel line disconnect tool that you might be able to rent from a nearby auto parts store.
Things You'll Need
- Socket set
- 5/16-inch fuel line disconnect tool
- Fuel pressure kit No. J-44321 or equivalent
- Flat-head screwdriver
- Clean, lint-free cloth
- New engine oil
- Inch-pound torque wrench
Testing the Fuel Pressure
Remove the two bolts on the front of the engine cover using a ratchet and socket, and lift the engine cover from the top of the engine. Place the cover in a safe location to prevent damage.
Find the intelligent power distribution module, which is the rectangular box located on the passenger’s side of the Titan’s firewall.
Open the IPDM and find the fuel pump fuse, which is the seventh fuse from the passenger’s side, in the top row of fuses. Pull this fuse with a slight wiggling motion to remove it. Set the fuse in a secure location for future re-installation.
Start the Titan’s engine and allow it to idle until the engine stalls. Crank the engine two additional times for five seconds each time to relieve any residual fuel pressure. Turn the ignition to the "Off" position.
Find where the fuel supply line connects to the Titan’s fuel rail inlet tube on the driver’s side of the engine and locate the cylinder-shaped plastic cover. Pull the cover upward to expose the connection point between the supply line and the fuel rail.
Guide a 5/16-inch fuel line disconnect tool to the inlet on the fuel rail, with the cylinder end facing the union point between the supply line and fuel rail. Wrap the connection point between the hoses with a clean, lint-free shop cloth to catch any residual gasoline. Pull upward on the disconnect tool and hold this upward force while pulling the supply line upward to disconnect it from the fuel rail inlet. Leave the disconnect tool inside the end of the fuel supply hose.
Connect the quick disconnect adapter No. J-44321, which is a part of fuel pressure kit No. J-44321, to the fuel pressure gauge. Guide the adapter through the hole in the disconnect tool, then press the tool upward and hold it. Press the adapter into the fuel supply hose as far as it will go, then release the disconnect tool to lock it into place. Tug lightly on the adapter to check that there is a good connection.
Connect the rubber hose included with the pressure kit to the inlet on the fuel rail. Tighten the hose clamp with a flat-head screwdriver.
Reinstall the fuel pump fuse into the IPDM and turn the ignition to the “Run” position for 10 seconds, then turn the ignition off for two seconds. Turn the ignition to the “Run” position again and check for any leaks from the gauge.
Start the engine and allow it to idle for roughly 15 minutes, checking the connections for fuel leakage every three minutes. At idling speed, the correct fuel pressure remains steady at roughly 51 psi. If the pressure is drastically low – more that 5 psi below the required pressure – there is a problem in the fuel system, such as a failed fuel pump, congested fuel lines or clogged fuel filter.
Removing Pressure Gauge
Relieve the fuel pressure following steps 3 and 4 in Section 1.
Wrap the connection point between the adapter and the fuel supply hose with a clean, lint-free cloth to catch any residual gasoline. Release the quick-release adapter from the fuel supply hose using the disconnect tool. Loosen the hose clamp on the hose connected to the fuel rail using a flat-head screwdriver. Remove the fuel pressure gauge and the quick disconnect tool.
Clean the end of both fuel tubes, the one on the fuel rail and the fuel supply tube, with a clean, lint-free cloth.
Apply a thin coat of new engine oil to the tip of the fuel rail tube to avoid damaging the O-ring inside the fuel supply tube. Guide the fuel supply tube over the fuel rail tube. Press the fuel supply tube downward until you hear the connector click into place.
Check the connection by verifying that you cannot see the white line painted on the fuel rail inlet tube and that the second flange on the tube is directly under the connector – there is no tube showing before the flange. Pull upward on the fuel supply tube with about 11 pounds of force to verify it made a good connection. If the fuel supply hose pops off, repeat the process from steps 3 through 5.
Reinstall the engine cover onto the top of the engine and tighten its retaining bolts to 49 inch-pounds, using an inch-pound torque wrench and socket.
Install the fuel pump fuse back into the IPDM and close the IPDM's lid. Turn the truck's ignition to the "Run" position for 10 seconds, then to the "Off" position for three seconds. Turn the ignition back to the "Run" position and check the connection point between the fuel rail inlet tube and the fuel supply hose for leaks.
Tips & Warnings
- Gasoline and its vapors are highly flammable. Do not smoke or have an open flame near your work area.
- Cars.com: 2006 Nissan Titan Features and Specs
- MSN Autos: 2004 Nissan Titan Engine Specs
- MSN Autos: Nissan Titan Overview
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