Very high fuel pressure - Taurus Car Club of America : Ford Taurus Forum
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post #1 of 10 (permalink) Old 08-05-2019, 11:54 PM Thread Starter
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Very high fuel pressure

Hello everyone I've been battling this problem for quite some time. It is a 2002 with the 3.0 OHV engine. When I have the key on and engine off the fuel pump continues to run instead of just priming. According to the scan tool the fuel pressure reads 89 psi even if the engine is running. The codes I'm getting are P0901 and oxygen sensor reading rich. I replaced the fuel pressure sensor with no change. I went through the wiring and I can't find anything wrong with it either. Has anyone had this happen or know what the problem could be.
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post #2 of 10 (permalink) Old 08-06-2019, 02:01 AM
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Sounds to me like a problem with the pump itself. It's just running at full voltage at all times instead of reacting based on demand and load. It likely won't last long in this state, lol. I'm not entirely sure how the fuel pump circuit works on this car and I don't have the diagrams handy anymore to see which part of the circuit might be the problem. Hopefully someone else can chime in.


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post #3 of 10 (permalink) Old 08-06-2019, 07:22 AM Thread Starter
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Thanks for the input. I kinda think the same thing. I'm also surprised that the pump has lasted this long. I'm thinking about changing the entire fuel pump unit. I'm hoping someone will know what is going wrong before I start throwing parts at it. I cut the the ground going to the fuel pump from the driver module and it still runs. Lol
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post #4 of 10 (permalink) Old 08-06-2019, 07:46 AM
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Quote:
Originally Posted by ice445 View Post
Sounds to me like a problem with the pump itself. It's just running at full voltage at all times instead of reacting based on demand and load. It likely won't last long in this state, lol. I'm not entirely sure how the fuel pump circuit works on this car and I don't have the diagrams handy anymore to see which part of the circuit might be the problem. Hopefully someone else can chime in.
See diag. Fuel pump runs by signal from the FPDM. It turns it off/on and regulates the effective volts to make the desired pressure around 40#. Pump cannot be at fault. Likely FPDM or PCM. FPDM is behind the rear passenger seat back.


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post #5 of 10 (permalink) Old 08-06-2019, 09:39 AM
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Chart is correct. The pump isn't the issue it responds to decisions made elsewhere, it doesn't make them
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post #6 of 10 (permalink) Old 08-06-2019, 11:03 AM Thread Starter
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The thing that is strange is that I cut the black and pink wire (which is the one that provides ground to turn on the pump) and the pump still runs. Wouldn't that rule out the FPDM and the PCM?

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post #7 of 10 (permalink) Old 08-06-2019, 09:11 PM
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Quote:
Originally Posted by racer5150 View Post
The thing that is strange is that I cut the black and pink wire (which is the one that provides ground to turn on the pump) and the pump still runs. Wouldn't that rule out the FPDM and the PCM?
Different information. The FPDM pulses the Bl/Pk wire to adjust the pump speed. Pulsed to ground. Cut the wire and the pump should be dead. If it runs, then there is a short to ground somewhere from the cut end to the pump motor. Turn the key on and the + (Wh?Rd) wire has battery volts on it. Maybe inside the gas tank. Maybe a wire on top of the tank.


-chart-
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post #8 of 10 (permalink) Old 08-06-2019, 09:19 PM
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There were recalls or TSB on some Taurus that had problems with the wiring harness that sits above the gas tank that got squeezed during installation between tank and unibody.
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post #9 of 10 (permalink) Old 08-06-2019, 10:26 PM Thread Starter
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Thanks guys. I've checked the wiring from the FPDM to inside the tank a while back and didn't find anything. I've had to have missed something. I'll check and see what I can find out about the TSBs and recalls Thanks again for the help
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post #10 of 10 (permalink) Old 08-07-2019, 02:35 AM
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Quote:
Originally Posted by chartmaker View Post
See diag. Fuel pump runs by signal from the FPDM. It turns it off/on and regulates the effective volts to make the desired pressure around 40#. Pump cannot be at fault. Likely FPDM or PCM. FPDM is behind the rear passenger seat back.


-chart-

Thanks for that. I'm glad you were able to pull that up. I'm getting rusty on too many of these things, I wish I still had my wiring diagram booklet


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