Ford 6.0L POWER STROKE, Service Procedures And General Diagnostics

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High Boost/High EP at WOT no Load
• If high boost (consistently over 14 psi MGP)
and high exhaust pressure (constantly over
23 psi EP) is present at WOT no load, the
VGT or VGT control valve may be at fault.
• To verify that the VGT is not being
commanded to a closed position, disconnect
the wiring at the VGT control valve and run
the engine at WOT.
• If the readings do not return to normal then
the VGT or VGT control valve are at fault.
Air in Fuel
G E N E R A L D I A G N O S T I C S
79
• Air in the fuel supply system can cause
rough run, white smoke and low power.
• To check for air in the fuel system, remove
the return line (to tank from fuel pump
module) from the fuel pump module.
• Install a 1/4” ID hose to the fuel pump
module and place the other end of the hose
into a diesel fuel safe container.
• Turn the ignition to the on position. The fuel
pump will run for approx. 20 sec.. Continue
to cycle the key to the on position until fuel
flows from the attached hose.
• Start the engine, run at WOT, and observe
the returning fuel for air.
• If air is present, the fuel will appear white,
foamy, or non-transparent. If no or very little
air is present in the fuel, the fuel exiting the
return hose will appear clear/transparent.
• Were to look?
a) Fuel pick up in the fuel tank.
b) Fuel supply line entering the fuel
pump module from the fuel tank.
c) Fuel return line entering the fuel pump
module from the engine.
d) Combustion leaks past the copper
washer on the injector.
VGTCV DISCONNECTED VGTCV DISCONNECTED