1995 Explorer will not start
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1995 Explorer will not start
1995 Explorer, 4 ltr. pushrod engine. No sound of fuel pump so changed... the pump, the filter, the pressure regulator, every relay, and the crankshaft positon sensor. 
Now the pump runs all the time and won't shut off. The engine will not start. You can feel the fuel goiing through the regulator and back to the tank. Tried to check pressure in the rail and got zero !! Actually used a tire pressure tester just to see if there was any pressure and got no reading. Like I said I think it's all just by-passing. Any ideas ???
Now the pump runs all the time and won't shut off. The engine will not start. You can feel the fuel goiing through the regulator and back to the tank. Tried to check pressure in the rail and got zero !! Actually used a tire pressure tester just to see if there was any pressure and got no reading. Like I said I think it's all just by-passing. Any ideas ???
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Might be a dumb question, but how does the fuel pressure regulator work? It has fuel in (from the fuel rail), a line that goes back to the tank, and a vacuum port. Does vacuum open it? Since all fuel is going back to the tank, is the new one I put on faulty? If vacuum opens it, it seems to me that whenever the engine runs (which this one does not) it would open ????
Postmaster
Joined: Dec 2001
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From: UT
The fuel pressure regulator is a basic, mechanical back pressure regulator. Operation basically looks like this. When the pump first comes on, the regulator stays closed until the desired pressure (40 psi) is reached. At that point, the regulator opens to allow the "excess" fuel to return to the tank, thus maintaining a constant pressure upstream of the regulator. Engine vacuum is used to "moderate" this pressure according to engine load. When vacuum is high (engine load low) and the engine "needs" less fuel, the pressure is reduced 5-10 psi over the basic set point. When vacuum is low (engine load high), the pressure increases to the above mentioned 40 psi.
If fuel is returning to the tank when the pressure is low and the pump running, that indicates that the regulator is stuck open.
If fuel is returning to the tank when the pressure is low and the pump running, that indicates that the regulator is stuck open.
Logistics Pro
Joined: Jun 2009
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From: Cedar Rapids, IA
Boilerperson, when you mention in your first post that the fuel pump runs all the time, are you meaning that as soon as you turn the key to the Run position, the pump kicks in and remains running as long as the key is left in Run? If so, I don't think that's just an issue with the FPR. Hopefully the pump doesn't also run with the key in the Off position.
-Rod
-Rod
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problem solved
Thanks for all the info and help. The fuel pump ran all the time with the key on. Turned out to be the computer !!! And I was surprised that it was less than $150 for reman unit. Thanks again for the help.
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