Fuel pump electrical circuit question???
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Junior User
Joined: May 2006
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Fuel pump electrical circuit question???
I have a '86 F350 which I am changing from a 460 gasoline engine to a 6.9 L diesel. I had planned to leave as much of the electrical system unchanged as possible. With this in mind I just unplugged the gasoline engine from the electrical system. However when I came to test the fuel pump (in the tank) by turning on the ignition key no fuel is pumped. I suspect that the fuel pump circuit is somehow connected thru the engine and will not pump without some signal from the engine that it is cranking.
Can someone with access to a electrical circuit diagram explain this and suggest what needs to be done to make the fuel pump operate?
Can someone with access to a electrical circuit diagram explain this and suggest what needs to be done to make the fuel pump operate?
Cargo Master
Joined: Aug 2003
Posts: 3,237
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From: Belleville, Ontario
Just some rookie thoughts.....
How much pressure does the in-tank pump produce? How long will the gas pump survive pumping heavier diesel fuel?
The 6.9 has a mechanical pump to send fuel to the injector pump from the tank. Would you be better off changing out the electric pump/sender for the correct diesel pickup/sender in the tank?
Just naturally curious.
AL.
The 6.9 has a mechanical pump to send fuel to the injector pump from the tank. Would you be better off changing out the electric pump/sender for the correct diesel pickup/sender in the tank?
Just naturally curious.
AL.
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Junior User
Joined: May 2006
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fuel pump change
Dealford,
Those are good questions. I actually have the diesel tank and had hoped to install it along with the engine. But this change out has taken longer than I expected and there is work that I need to do with this vehicle. My thinkng was to get it operational then tidy up the details later.
Those are good questions. I actually have the diesel tank and had hoped to install it along with the engine. But this change out has taken longer than I expected and there is work that I need to do with this vehicle. My thinkng was to get it operational then tidy up the details later.
Moderator
Joined: Jan 2001
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From: Virginia
The 460 has a lot of circuitry and wiring associated with the fuel pump. One of the main things you are missing now is the oil pressure sensor. You must have also changed some of the wiring around the starter solenoid.
The starter solenoid sent power to the fuel pump relay during cranking, and then the fuel pump relay got it's power from the oil pressure switch on the engine after it started. This is how it verified the engine was running. You also have a safety cutoff switch somewhere down the line from the relay to the pump. This is a pendulum type switch that swings and trips in case of a accident to cut the pump off. It has to be reset manually.
The starter solenoid sent power to the fuel pump relay during cranking, and then the fuel pump relay got it's power from the oil pressure switch on the engine after it started. This is how it verified the engine was running. You also have a safety cutoff switch somewhere down the line from the relay to the pump. This is a pendulum type switch that swings and trips in case of a accident to cut the pump off. It has to be reset manually.
