91 351W (EFI... EEC-IV???) help needed
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Sounds like the truck originally had a 2 stage pump system that has been modified, low pres pump intank, and high press pump on the chassis. Is there another pump somewhere else now, or is it just running off the intank pump? Or are you saying the factory wiring on the chassis pump has been chopped up and partially bypassed?
The pumps should only run when the engine is running...obviously. If they run all the time then the pump relay has probably been bypassed.
The pumps should only run when the engine is running...obviously. If they run all the time then the pump relay has probably been bypassed.
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Freshman User
Joined: Mar 2007
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Likes: 0
Originally Posted by Conanski
Sounds like the truck originally had a 2 stage pump system that has been modified, low pres pump intank, and high press pump on the chassis. Is there another pump somewhere else now, or is it just running off the intank pump? Or are you saying the factory wiring on the chassis pump has been chopped up and partially bypassed?
The pumps should only run when the engine is running...obviously. If they run all the time then the pump relay has probably been bypassed.
The pumps should only run when the engine is running...obviously. If they run all the time then the pump relay has probably been bypassed.
However, the 2nd-stage pump is not connected to it's factory wiring, instead it is run thru a toggle switch directly into the ignition - if the ignition is on, the 2nd stage pump runs, unless turned off manually.
The factory fuel pump wiring is still there, it's just not hooked up to anything.
I am considering wiring it to the fuel pump in paralell, so that the jerry-rigged switch acts as an override (to force operation), not as an on/off switch....
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Freshman User
Joined: Mar 2007
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Ok, O2 sensor is dead - big time... As in physically falling apart...
Now, how do I get it OUT?
I've tried PB Blaster - won't budge...
Should I be doing this with the exhaust hot? Do I need a torch? How do you get this thing OUT?
Now, how do I get it OUT?
I've tried PB Blaster - won't budge...
Should I be doing this with the exhaust hot? Do I need a torch? How do you get this thing OUT?
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I was going to say not to change it until you've ruled everything else out, as the sensor is last in line, but if it's physically falling apart, then that's bad. 
I would soak it in PB blaster several times over the course of a week and then run the engine for about 15 minutes after you do it. When you're ready to take it out, warm the engine for about 5 minutes and have at it with a big open ended wrench. They sell special sockets for O2 sensors, but I don't like them as they like to spread when you really reef on them.
I would soak it in PB blaster several times over the course of a week and then run the engine for about 15 minutes after you do it. When you're ready to take it out, warm the engine for about 5 minutes and have at it with a big open ended wrench. They sell special sockets for O2 sensors, but I don't like them as they like to spread when you really reef on them.
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