1991 1999 ford explorer chilton User Manual

On the 4.0L engine, remove the old fuel supply manifold gasket and clean the mating surfaces
Remove the fuel injectors from the intake manifold by lifting while gently rocking them from side to
side
10. 
Remove the injectors from the engine by gently rocking it while pulling upwards
Place all removed components on a clean surface to prevent contamination by dirt or grease.
11. 
Never use silicone grease; it will clog the injector. All injectors and the fuel rail must be handled with
extreme care to...

The injector has O-rings at the nozzle (A) and at the fuel supply manifold (B). Replace any
damaged seals
Examine the injector O-rings for deterioration damage, replacing them as needed.
12. 
Make sure the injector caps are clean and free from contamination or damage.
13. 
To install: Lubricate all O-rings with clean engine oil, then install the injectors into the fuel rail using a light
twisting/pushing motion.
14. 
On the 4.0L (VIN X) engine, position a new fuel rail gasket to the lower intake...

A noid light can be attached to the fuel injector harness in order to test for injector pulse
Cross-sectional view of a typical MFI fuel injector
The fuel injectors can be tested with a Digital Volt-Ohmmeter (DVOM). To test an injector, detach the
engine wiring harness connector from it. This may require removing the upper intake manifold or other engine
components.
Once access to the injector is gained and the wiring is disconnected from it, set the DVOM to measure
resistance (ohms). Measure the...

Cutaway view of the fuel pressure regulator
Except the 4.0L SOHC (VIN E) Engine
Depressurize the fuel system; remove shielding as needed.
1. 
Remove the vacuum line at the pressure regulator.
2. 
Fuel pressure regulator on the 2.3L and 2.5L engine-3.0L and 5.0L engines are similar Click to enlarge
HOW TO USE THIS BOOK
634 REMOVAL & INSTALLATION 

Fuel pressure regulator on the 2.9L engine
Click to enlarge
Fuel pressure regulator on the 4.0L engine HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 635 

To remove the fuel pressure regulator, first remove the vacuum line from the regulator ...
... then loosen the fuel return line fitting ...... and disconnect it from the regulator
If necessary, disconnect the fuel return line from the regulator.
3. 
Some engines use two standard hex head bolts to retain the regulator instead of the Allen® head screws. HOW TO USE THIS BOOK
636 REMOVAL & INSTALLATION 

Remove the regulator attaching bolts ...
... then pull the regulator from the supply manifold using a slight rocking motion to unseat the O-ring seal
Remove the three Allen® head retaining screws from the regulator housing.
4. 
Remove the pressure regulator assembly, gasket and O-ring. Discard the gasket and check the O-ring
for signs of cracks or deterioration.
5.  HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 637 

Inspect the regulator O-ring seal and replace it if needed. A small pick will aid in removing the
old seal
To install:
Clean the gasket mating surfaces. If scraping is necessary, be careful not to damage the fuel pressure
regulator or supply line gasket mating surfaces.
6. 
Lubricate the pressure regulator O-ring with light engine oil. Do not use silicone grease; it will clog
the injectors.
7. 
Install the O-ring and a new gasket on the pressure regulator.
8. 
Install the pressure regulator on the fuel...

Remove the four bolts (arrows) that attach the regulator/fuel lines to the supply manifold
Remove the bolts and the fuel supply and return lines at the injection manifold.
5. 
Unbolt the upper fuel line support bracket from the valve cover.
6. 
Remove the fuel supply and return line assembly from the vehicle with the regulator assembly
attached.
7. 
To install: Clean the gasket mating surfaces. If scraping is necessary, be careful not to damage the fuel pressure
regulator or supply line gasket mating...

Position the fuel pressure regulator assembly to the supply manifold (arrows)
Install the O-ring and a new gasket on the pressure regulator.
10. 
Install the fuel supply and return line assembly.
11. 
Fasten the upper fuel line support bracket to the valve cover.
12. 
Install the bolts that fasten the fuel supply and return lines to the injector manifold.
13. 
Connect the fuel supply and return lines.
14. 
Connect the vacuum line to the pressure regulator.
15. 
Install the upper intake manifold.
16....