460 fuel system
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4wd Low
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460 fuel system
Hi I'm wondering how the gas pump system works on the 97 fuel injected 460. Does the pump run all the time and rely on the vacuum fuel pump regulator to push whatevers not needed back through the return line? My relay seems to kick on for 2 secs when I turn the key on but then the pump turns off. I can manully jumper the wires and the pump stays on. Whats controlling the relay? Thanks for any help
Fleet Owner
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From: Easton,Ks
The PCM controls the fuel pump relay by grounding it.
The fuel pump relay will close for one second each time the key is turn to the run position.
The fuel pressure regulator will adjust the pressure depending on the vacuum and send fuel back to the selected tank to regulate the pressure.
The selected fuel pump will run all the time the engine is cranking or running but not when the key is on and the engine is not running.
From the Ford shop manual.
Fuel Pump Circuit Operation
When the ignition is switched to the ON position, it turns the EEC Power Relay on. The EEC Power Relay provides power to the EEC-IV processor and the control side of the fuel pump relay. Power for the fuel pump is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flow is through the fuel pump relay and Inertia Fuel Shutoff (IFS) switch to the fuel pump. The IFS switch is a safety device used to shut off the fuel pump in the event of a collision. If the IFS switch is "tripped," it must be reset by depressing the white or red button on the top of the switch. The fuel pump relay is controlled by the Powertrain Control Module (PCM).
When the ignition switch is turned to the ON position, the fuel pump will operate. If the ignition switch is not turned to the START position, the PCM will shut the fuel pump off after approximately one second. The PCM will operate the fuel pump when the ignition is in the START position to provide fuel while cranking.
After the engine starts, the PCM will continue to operate the fuel pump unless the engine stops, engine speed drops below 120 rpm, or the IFS switch is "tripped."
The fuel pump relay will close for one second each time the key is turn to the run position.
The fuel pressure regulator will adjust the pressure depending on the vacuum and send fuel back to the selected tank to regulate the pressure.
The selected fuel pump will run all the time the engine is cranking or running but not when the key is on and the engine is not running.
From the Ford shop manual.
Fuel Pump Circuit Operation
When the ignition is switched to the ON position, it turns the EEC Power Relay on. The EEC Power Relay provides power to the EEC-IV processor and the control side of the fuel pump relay. Power for the fuel pump is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flow is through the fuel pump relay and Inertia Fuel Shutoff (IFS) switch to the fuel pump. The IFS switch is a safety device used to shut off the fuel pump in the event of a collision. If the IFS switch is "tripped," it must be reset by depressing the white or red button on the top of the switch. The fuel pump relay is controlled by the Powertrain Control Module (PCM).
When the ignition switch is turned to the ON position, the fuel pump will operate. If the ignition switch is not turned to the START position, the PCM will shut the fuel pump off after approximately one second. The PCM will operate the fuel pump when the ignition is in the START position to provide fuel while cranking.
After the engine starts, the PCM will continue to operate the fuel pump unless the engine stops, engine speed drops below 120 rpm, or the IFS switch is "tripped."
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4wd Low
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Great info thank you. Another quick question: How does the return fuel know what tank is selected? It looked like the midship tank was just Teed into the fuel tubes. Seems to be pulling from the rear tank but returning to the mid tank. Maybe a valve in the fuel pump is supposed to close when the tank is not selected?
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Yes your midship tank has a bad valve in it.
The valves will be closed in the fuel module when the pump in the module is not pumping.
In order to continuously supply the fuel injectors with clean fuel at a controlled pressure, all systems require a fuel pump with a discharge check valve, a reservoir surrounding the pump inlet, a fine mesh fuel filter, a pressure regulator, a fuel supply and return system of tubes and hoses, a fuel tank, and a fuel supply manifold or fuel rail connected to the fuel injectors. The Powertrain Control Module (PCM) controls power input to the fuel delivery system and provides correct timing for the fuel injectors.
The Fuel Delivery Assembly consists of the fuel pump inside a reservoir that is attached to the pump and sender assembly. In a two tank system there is one assembly per tank. The sender assembly handles the switching of the fuel through internal valves.
Shuttle Selector Valve
The Shuttle Selector Valve opens the return line to the tank when the fuel pressure on the shuttle diaphragm exceeds the opposing spring force. The return flow is directed to the appropriate tank on vehicles equipped with dual tanks.
Supply Check Valve
The Supply Check Valve, which is normally closed, opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.
Venturi Jet Pump
A portion of the high pressure flow from the pump is diverted to operate the Venturi Jet Pump. The Venturi Pump draws fuel from the tank into the assembly. This process ensures an adequate fuel supply to the pump during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fuel fill levels.
The inlet of the Venturi Pump has a nylon filter on it to prevent dirt and other particulate matter from entering the system. Water in the fuel tank can pass through the filter in small quantities.
Attachment 280308
Attachment 283962
Attachment 281295
/
The valves will be closed in the fuel module when the pump in the module is not pumping.
In order to continuously supply the fuel injectors with clean fuel at a controlled pressure, all systems require a fuel pump with a discharge check valve, a reservoir surrounding the pump inlet, a fine mesh fuel filter, a pressure regulator, a fuel supply and return system of tubes and hoses, a fuel tank, and a fuel supply manifold or fuel rail connected to the fuel injectors. The Powertrain Control Module (PCM) controls power input to the fuel delivery system and provides correct timing for the fuel injectors.
The Fuel Delivery Assembly consists of the fuel pump inside a reservoir that is attached to the pump and sender assembly. In a two tank system there is one assembly per tank. The sender assembly handles the switching of the fuel through internal valves.
Shuttle Selector Valve
The Shuttle Selector Valve opens the return line to the tank when the fuel pressure on the shuttle diaphragm exceeds the opposing spring force. The return flow is directed to the appropriate tank on vehicles equipped with dual tanks.
Supply Check Valve
The Supply Check Valve, which is normally closed, opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.
Venturi Jet Pump
A portion of the high pressure flow from the pump is diverted to operate the Venturi Jet Pump. The Venturi Pump draws fuel from the tank into the assembly. This process ensures an adequate fuel supply to the pump during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fuel fill levels.
The inlet of the Venturi Pump has a nylon filter on it to prevent dirt and other particulate matter from entering the system. Water in the fuel tank can pass through the filter in small quantities.
Attachment 280308
Attachment 283962
Attachment 281295
/
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