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Repair1014U, Repair Shop Ower
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1994 Ford F350 7.3 Turbo Diesel. This truck was towed in. I

Customer Question

1994 Ford F350 7.3 Turbo Diesel. This truck was towed in. I tried to start it but fuel was leaking from all the return line caps/o-rings. Removed all the injectors, put new copper and o-rings, replaced the return line caps and lines.

Still will not start so I have a few questions:
What should the fuel pressure be?
What is the pressure switch that is mounted to the filter housing on the top fron of the engine?
Any other diagnostic suggestions?
Submitted: 1 year ago.
Category: Ford
Expert:  Repair1014U replied 1 year ago.
Hello,

1. First verify that there is no air in the fuel getting to the injection pump. Tee in a clear piece of hose and have an assistant crank the engine looking for air in the fuel. If found, pressurize the fuel system by applying 1-2 PSI of air pressure to the fuel tank and look for any leaks that may not show up under normal conditions and repair as needed.

2. If there is no air in the fuel and there is at least 1-2 PSI of fuel pressure cranking, check for fuel at the fuel injectors by cracking one of the fuel lines loose about 1/2 turn. Crank the engine and look for fuel to squirt out at the connection.

3. If there is no fuel at the injectors, check for battery voltage to the fuel shut off solenoid on the Red/Light Green (R/LG) wire at the injection pump.

4. If battery voltage is present, remove the wire from the solenoid and tap the wire to the solenoid, listening for it to click. If it does, suspect a problem with the injection pump.

Fuel Pressure
Pressure 1 (PSI) Pressure 2 (PSI) Pressure 3 (PSI)
Range Note Range Note Range Note
35.0 - 40.0 Y171 25.0 - 31.0 Y172 69.0 - 85.0 Y173
Y171: System pressure with ignition on, fuel pump running.
Y172: System pressure, idling.
Y173: Fuel pump pressure.

Fuel System

WARNING: USE MOTORCRAFT® FUEL FILTER/WATER SEPARATOR FD-829 OR EQUIVALENT.

Fuel from the tank is routed to the fuel supply pump through a combination fuel filter, heater and water separator. The filter header contains a continuous vent (orifice bleed- off system) which aids starting by eliminating the need to manually prime the fuel filter. A vacuum switch is incorporated into the fuel filter header which will activate an instrument panel lamp, indicating the need for filter replacement. The water separator portion of the filter assembly has a probe which activates an instrument panel lamp when the filter requires draining at the water and sediment drain (located on the bottom of the assembly).

NOTE: Proper filtration of diesel fuel cannot be overemphasized. It is essential for long component life and reliability.

Fuel enters the inlet of the injection pump and is delivered under high pressure through injection nozzles into the engine cylinders for combustion. Each nozzle incorporates a fuel return fitting that returns excess fuel to the fuel tank. Excess fuel from the injection pump and each injection nozzle is collected in bleed-off lines and returned to the fuel tank.

Injection nozzles are located on the inboard side of the cylinder head. This configuration provides better access to the engine for servicing.

The fuel shutoff solenoid controls the flow of fuel into the injection pump charging circuit (high pressure). With the ignition switch in START or RUN, the solenoid is energized and fuel is allowed to flow to the injection pump charging circuit. With the ignition switch off, fuel flow to the injection pump charging circuit stops.

Fuel Flow, Naturally-Aspirated Diesel






Fuel Flow, IDI Turbo Diesel



Item Description
1 Fuel Return
2 Injection Pump
3 Fuel Tank
4 Orifice Bleed-Off
5 Fuel Supply Line
6 Fuel Filter/Heater/Water Separator
7 Fuel Supply Pump
8 Injection Nozzles

Injection Pump

The diesel fuel injection pump accurately meters and delivers fuel to a nozzle in each cylinder at high pressure and at precisely timed intervals.

The injection pump used on both engines is the same model, but the injection pump on the IDI turbo diesel engine has a higher fuel flow rate to compensate for the increased airflow. When replacing a fuel injection pump, make sure it is designed for that specific diesel application.

Refer to following illustration for pump operating principles. Fuel flows into the injection pump inlet through an inlet filter screen (1). Fuel then flows to the vane-type fuel transfer pump (2). Excess fuel from the transfer pump is bypassed through the pressure regulator assembly (3) to the suction side.

Fuel under transfer pump pressure flows through the center of the transfer pump rotor, past the rotor retainers (4) into the hydraulic head. It then flows through a connecting passage (5) in the head to the automatic advance (6) and up through a radial passage (7) to the metering valve (8). The position of the metering valve, controlled by a governor, regulates fuel flow into the radial charging passage (9) which incorporates the head charging ports. As the rotor revolves, the two rotor inlet passages (10) align with the charging ports in the hydraulic head, allowing fuel to flow into the pumping chamber. With further rotation, the inlet passages move out of alignment and the discharge port of the rotor aligns with one of the head outlets. While the discharge port is opened, the rollers (11) contact the cam lobes forcing the plungers together. Fuel trapped between the plungers is then pressurized and delivered by the nozzle to the combustion chamber.

In addition, an air vent passage (12) in the hydraulic head connects the outlet side of the transfer pump with the pump housing. This allows air and some fuel to be bled back to the fuel tank through the return line. Fuel bypassed in this way fills the housing, lubricates the internal components, cools and carries off any small air bubbles.

Injection Pump Internal View


Injection Nozzle Assemblies

Description

The injection nozzles between the two engines are similar in design, but have different flow rates. The naturally-aspirated injection nozzle can be identified by the stamped code "E". The IDI turbo injection nozzle can be identified by the stamped code "G".

The injection nozzles are of the inwardly opening, differential, hydraulically operated, pintle-type. Their function is to direct a metered amount of fuel, under high pressure from the fuel injection pump, into the engine combustion chamber.

The injection nozzle assembly consists of two subassemblies. The nozzle holder retains the nozzle in its correct position in the cylinder head and provides channels for conducting diesel fuel to the nozzle. The nozzle consists of two parts: valve body and nozzle valve. These parts are lapped to form an extremely close-fitting matched set.

The nozzle valve carries an extension at its lower end, called the pintle.

Operation

A metered quantity of fuel passes through ducts to the pressure chamber located just above the spring seat. At the instant the pressure of fuel acting on the differential area of the valve exceeds a predetermined spring-load, it lifts the valve from its seat and fuel flows from the nozzle. Fuel cut-off occurs as the valve is seated by the nozzle spring. A small amount of fuel leakage to the spring cavity is necessary for lubrication. This fuel leakage drains through to a leak-off outlet.

Nozzle opening pressure and spray pattern should be inspected every 96,500 km (60,000 miles). Refer to Nozzle Testing in the Powertrain Control/Emissions Diagnosis Manual .

Injection Nozzle and Holder Assembly



Item Description
1 Fuel Return Tee
2 High Pressure Connection
3 Nozzle Retaining Threads
4 Spring
5 Spring Seat
6 Nozzle Valve
7 Pintle
8 Nozzle Cap Nut (Retainer)
9 Copper Gasket
10 Valve Body
11 Spacer With Dowels
12 Pressure Adjusting Shims
13 Nozzle Holder Body
14 Nozzle Mounting Surface
15 O-Ring Seals
16 Nozzle Tip Part Number Location
17 Stamped Code

Make sure it is not the injetor pump.

Please let me know how you do and if you would like more help.

Thank you
Customer: replied 1 year ago.

I'll proceed as you advise - in the morning and let you know.


 


What is that pressure sensor that is mounted on the fuel filter on top of the engine?


 


Thank you


Tom


 

Expert:  Repair1014U replied 1 year ago.
ok thank yo and please let me know, thank you
Customer: replied 1 year ago.

What is that pressure sensor that is mounted on the fuel filter on top of the engine?

Expert:  Repair1014U replied 1 year ago.
Here is the diagram for the fuel system for you.

Fuel System

The fuel injection system used on the DI turbo diesel engine is controlled by the powertrain control module (PCM) (12A650). Fuel is drawn from the fuel tank (9002) by a fuel pump (9350) which circulates fuel at low pressure, first through the fuel filter (9155) and then into the cylinder head fuel galleries at high pressure. Fuel is delivered into the combustion chamber through electronically-controlled/hydraulically-actuated fuel injectors (9F593).

The cylinder heads (6049) are specially designed to incorporate electronically-controlled/hydraulically-activated fuel injectors. The fuel injectors are located near the center of the combustion chambers in the cylinder head between the rocker arms (6564).

Fuel is delivered into the electronically-controlled/hydraulically-actuated fuel injectors from the fuel galleries. After fuel enters the plunger area of the fuel injector the powertrain control module sends a signal of when and how much fuel should be delivered into the combustion chamber. (Fuel injected into the combustion chamber can be pressurized up to 124,110 kPa [18,000 psi] depending on the fuel demand determined by the powertrain control module.) The fuel injector utilizes a conventional nozzle/valve tip arrangement and fuel pressures are maintained through hydraulic actuation.

The hydraulic fluid used to actuate the fuel injector is engine oil, which is supplied by a stand-alone high pressure oil pump. Oil is supplied to the high pressure oil pump reservoir from a gerotor oil pump (6600). The high pressure oil pump is located in the engine "V" mounted to the cylinder blocks (6010).

The high pressure oil pump is a gear-driven, seven-plunger, swash-plate pump, which is driven by the camshaft (6250). Oil is pumped from the reservoir through high pressure oil lines into machined galleries in the cylinder head. These galleries route the high pressure oil into the upper portion of the fuel injector. When the fuel injector is energized, a poppet valve is opened by an electronic solenoid mounted on the fuel injector. The oil pressure flows into the fuel injector and acts on an amplifier piston. Fuel is injected into the combustion chamber. When injection is ended the high pressure oil on top of the amplifier piston is vented by the poppet valve through the top portion of the fuel injector to return back to the oil pan (6675).

Fuel System Components


Item Part Number Description
1 9155 Fuel Filter
2 9C334 Fuel Tube Clamp
3 Fuel Filter Supply Hose
4 9E313 Fuel Shield
5 9350 Fuel Pump
6 9N693 Fuel Pump Seal
7 Fuel Pump Tappet (Part of 9350)
8 9D308 Fuel Return Hose
9 9D308 Fuel Return Hose
10 9C330 Fuel Pump Supply Tube
11 Fuel Supply and Return Tube Clamp
12 9A564 Fuel Return Tube
13 Fuel Supply and Return Hose Clamp
14 Fuel Pump Fitting Gasket
15 Fuel Pump Outlet Bolt
16 9A555 Fuel Injection Tube
17 45 Degree Street Elbow
18 45 Degree Street Elbow
19 Oil Deflector
20 Bolt
21 9F593 Fuel Injector
22 Fuel Injector Hold Down Clamp (Part of 9E527)
23 Backup Ring (Part of 9E527)
24 Cushion Ring (Part of 9E527)
25 Fuel Injector Upper Seal (Part of 9E527)
26 Fuel Injector Middle Seal (Part of 9E527)
27 Cushion Ring (Part of 9E527)
28 Fuel Injector Lower Seal (Part of 9E527)
29 Fuel Injector Gasket (Part of 9E527)
30 Elbow and Plug O-Ring
31 90 Degree High Pressure Hose Elbow
32 9K260 Fuel Line Sleeve
33 High Pressure Manifold Supply Hose Clamp
34 9D308 Fuel Return Hose
35 Fuel Return Connector (LH)
36 High Pressure Oil Pump Supply Hose
37 Elbow
38 Injection Pressure Regulator
39 Connector
40 High Pressure Oil Pump Flange Gasket
41 High Pressure Oil Pump Assembly
42 9K260 Fuel Line Sleeve
43 High Pressure Oil Pump Supply Hose Clamp
44 90 Degree Fuel Return Elbow (RH)
45 High Pressure Oil Pump Supply Hose
46 90 Degree High Pressure Hose Elbow
47 Supply Rail Plug with O-Ring
48 Straight Connector
49 9D308 Fuel Return Hose
50 9K260 Fuel Line Sleeve
51 Fuel Return Hose Elbow
52 Fuel Return Hose Elbow
53 9K260 Fuel Line Sleeve
54 Fuel Filter Water Drain Hose
55 Water Drain Tube
56 9C334 Fuel Tube Clamp
57 Water Drain Tube Clip


Fuel Flow





Item Part Number Description
1 9155 Fuel Filter
2 Tank Return Orifices (Part of 9155)
3 Strainer Assembly (Part of 9155)
4 Fuel Pressure Regulator (Part of 9155)
5 Shrader Valve (Part of 9155)
6 6049 Cylinder Heads
7 9A564 Fuel Return Tubes
8 Piston Stage (Part of 9350)
9 9002 Fuel Tank
10 Diaphragm Stage (Part of 9350)

Please let me know how you do. Thank you

Customer: replied 1 year ago.

Thank you for the great information. Only problem is that the links tp the images do not work.

Expert:  Repair1014U replied 1 year ago.
Ok see if this is better for you
graphic

Item Part Number Description
1 9155 Fuel Filter
2 9C334 Fuel Tube Clamp
3 Fuel Filter Supply Hose
4 9E313 Fuel Shield
5 9350 Fuel Pump
6 9N693 Fuel Pump Seal
7 Fuel Pump Tappet (Part of 9350)
8 9D308 Fuel Return Hose
9 9D308 Fuel Return Hose
10 9C330 Fuel Pump Supply Tube
11 Fuel Supply and Return Tube Clamp
12 9A564 Fuel Return Tube
13 Fuel Supply and Return Hose Clamp
14 Fuel Pump Fitting Gasket
15 Fuel Pump Outlet Bolt
16 9A555 Fuel Injection Tube
17 45 Degree Street Elbow
18 45 Degree Street Elbow
19 Oil Deflector
20 Bolt
21 9F593 Fuel Injector
22 Fuel Injector Hold Down Clamp (Part of 9E527)
23 Backup Ring (Part of 9E527)
24 Cushion Ring (Part of 9E527)
25 Fuel Injector Upper Seal (Part of 9E527)
26 Fuel Injector Middle Seal (Part of 9E527)
27 Cushion Ring (Part of 9E527)
28 Fuel Injector Lower Seal (Part of 9E527)
29 Fuel Injector Gasket (Part of 9E527)
30 Elbow and Plug O-Ring
31 90 Degree High Pressure Hose Elbow
32 9K260 Fuel Line Sleeve
33 High Pressure Manifold Supply Hose Clamp
34 9D308 Fuel Return Hose
35 Fuel Return Connector (LH)
36 High Pressure Oil Pump Supply Hose
37 Elbow
38 Injection Pressure Regulator
39 Connector
40 High Pressure Oil Pump Flange Gasket
41 High Pressure Oil Pump Assembly
42 9K260 Fuel Line Sleeve
43 High Pressure Oil Pump Supply Hose Clamp
44 90 Degree Fuel Return Elbow (RH)
45 High Pressure Oil Pump Supply Hose
46 90 Degree High Pressure Hose Elbow
47 Supply Rail Plug with O-Ring
48 Straight Connector
49 9D308 Fuel Return Hose
50 9K260 Fuel Line Sleeve
51 Fuel Return Hose Elbow
52 Fuel Return Hose Elbow
53 9K260 Fuel Line Sleeve
54 Fuel Filter Water Drain Hose
55 Water Drain Tube
56 9C334 Fuel Tube Clamp
57 Water Drain Tube Clip



Expert:  Repair1014U replied 1 year ago.
graphic

Item Part Number Description
1 9155 Fuel Filter
2 Tank Return Orifices (Part of 9155)
3 Strainer Assembly (Part of 9155)
4 Fuel Pressure Regulator (Part of 9155)
5 Shrader Valve (Part of 9155)
6 6049 Cylinder Heads
7 9A564 Fuel Return Tubes
8 Piston Stage (Part of 9350)
9 9002 Fuel Tank
10 Diaphragm Stage (Part of 9350)
Repair1014U, Repair Shop Ower
Category: Ford
Satisfied Customers: 709
Experience: Diagnosticas & Electrical
Repair1014U and 3 other Ford Specialists are ready to help you
Customer: replied 1 year ago.

Hello,

 

Did you get my question - below?

 

Good Morning.

Would you mind answering a couple more questions?

 

1. What does the pressure switch on the filter actually do?

 

2. The wiring harness that goes to this pressure switch has two other wires. One is attached to the filter housing (brown/green) and another single wire connector with a round connector (black)is sitting loose. Do you know where this wire should go? or have a schematic?

 

Thank you

Tom

Expert:  Repair1014U replied 1 year ago.
Hello,

I just received your message because I just got home and I can help you with that. I need to eat dinner now and I will continue to help you. Thank you for the accept.
Expert:  Repair1014U replied 1 year ago.
Hello, my site I use for the information I would like to send you and the wire diagram is down for up dates. Can I get this to you in the morning for you? I am so so so sorry about that.
Customer: replied 1 year ago.

Sure, no problem


 

Expert:  Repair1014U replied 1 year ago.
ok thank you, I just checked it again and it is still doing it's up dates.
Expert:  Repair1014U replied 1 year ago.
Ok

DIESEL DIAGNOSIS — 7.3L DI ENGINE: CONTROL SYSTEM DIAGNOSTIC SHEET REFERENCE (ON BOARD DIAGNOSTICS I A)
1994 PCED On Board Diagnostics I A SECTION 18A: Diesel Diagnosis — 7.3L DI Engine

Control System Diagnostic Sheet Reference

PCM Pin Descriptions and Expected Values


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Customer: replied 1 year ago.

Hello,


 


I can only open the middle image. The top and bottom will not open. Also, if you could just answer the two questions I would appreciate it.

Expert:  Repair1014U replied 1 year ago.
ok, are you reffering to the Injection Pressure Regulator?
Or the Oil Pressure Switch?
I want to make sure I have the correct one to answer for you, sorry about that.
The wire that is brown and green I do not show that on my wire diagrams can you double check the colors and I will recheck the wire diagrams for you to be able to tell you where is does goes. Thank you and so sorry for the delay.

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