Low fuel pressure, large leak - Ford Powerstroke Diesel Forum
General 6.7 Discussion (2011-2016) General 6.7 Discussion

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post #1 of 44 Old 05-01-2017, 03:38 PM Thread Starter
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Low fuel pressure, large leak

Hi, I have a 2011 F-550 flatbed wrecker with the 6.7 diesel. It is throwing codes p0093 and p228e. everytime it suddenly stalls while driving. It will stall about 3 times within a mile of driving at 45 mph. I can drop it in nuetral, turn the keys off then on and will crank right up. On the scanner I see the frame pump shutting off when it dies. Using freeze frame, there is no evidence of loss of pressure when the stall occurs.
A new high pressure and low pressure pump have been installed as well as the fuel pressure regulator and fuel pressure sensor. Nothing has changed the condition.
Does anyone have any thoughts about what's going on?
I am convinced that the PCM is shutting the motor down.
I ran it down the road with the pressure sensor unplugged and though it was in limited power mode, it never stalled in ten miles.
Thanks
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post #2 of 44 Old 05-01-2017, 07:06 PM
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So, before it dies, the fpl PID (fuel pump low) changes from not low to low?

The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark.
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post #3 of 44 Old 05-02-2017, 04:13 AM Thread Starter
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No,, Kaya, it goes from not low to low as it dies. I fixed the frame pump to run all the time with a jumper wire and the truck still stalls and because of the jumper wire, the pump is running when it stalls.

FTR, When this little experiment failed, I returned the wiring back to normal to resume testing.

Last edited by dellis; 05-02-2017 at 04:16 AM.
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post #4 of 44 Old 05-02-2017, 06:05 AM
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Quote:
Originally Posted by dellis View Post
No,, Kaya, it goes from not low to low as it dies. I fixed the frame pump to run all the time with a jumper wire and the truck still stalls and because of the jumper wire, the pump is running when it stalls.

FTR, When this little experiment failed, I returned the wiring back to normal to resume testing.
Do you use any additives?
That is not a pump command from the PCM. That is supply pressure being lost.
What I would do is install a vacuum gauge teed into the supply line between the tank and low pressure pump.
This will tell you if there's a restriction in the tank

The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark.
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post #5 of 44 Old 05-02-2017, 10:16 AM Thread Starter
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Hi Kaya, I teed in at the sending unit and found one inch of vaccum while pump was running. I had both lines off at first and noticed that as soon as I turned the key on, fuel was returning very quickly from the return line to the tank.
No, I dont use additives.
BTW thanks for getting involved
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post #6 of 44 Old 05-02-2017, 11:31 AM
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you need to observe vacuum as it dies. you are teed into the lpfp supply?
and sorry, just want to be sure, it goes from not low to low before the engine dies?

The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark.
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post #7 of 44 Old 05-02-2017, 12:24 PM Thread Starter
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Modified fuel volume control solenoid

Would one of these benefit a 6.7 with low fuel pressure problem when there's no obvious cause for the p0093 code?
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post #8 of 44 Old 05-02-2017, 07:25 PM
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Low fuel pressure = somewhere in the fuel system something is plugged or the high pressure pump is going or a sensor is bad
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post #9 of 44 Old 05-03-2017, 03:26 AM Thread Starter
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The vacuum disappeared as soon as the engine died and it went from not low to low at the same time.
On the scanner, the drop in high pressure can be observed to drop as the engine winds down to 0 rpm. It's like it only lost high pressure "because" it lost low pressure first but like I said, when I tripped the low pressure pump to run all the time, the drop in high pressure was the same.
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post #10 of 44 Old 05-03-2017, 04:39 AM Thread Starter
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I have a question.. On my scanner with key on engine off, frame pump running, I see 0 lbs of fuel pressure. I also know about the fuel pressure switch on the low pressure feed pipe to the high pressure pump.

Do you know at what pressure this switch activates and deactivates the system while the engone is running?
(Learned) This switch is designed to deactivate the fuel supply when the low pressure does not prescribed level.

Last edited by dellis; 05-03-2017 at 05:35 AM.
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