Need help! P0172 Rich 80+ psi fuel pressure

Discussion in '1998 - 2011 Ford Ranger' started by Richard1316, Nov 28, 2019.

  1. Richard1316

    Richard1316 New Member

    My truck is a 2011 2.3 ranger

    I'm still kind of a noob when it comes to working on vehicles. I am an HVAC technician by trade though so I am naturally mechanically inclined and need help determining what my next repairs should be.

    The past month or so I've would get a check engine light that would pop on every now and then. This whole time I've been noticing that the truck would start fine in the mornings and after work, but as soon as I pulled onto the road and gave it a little gas it would lose all power and then steadily get it back as I drove for the next minute or two. Now the past few days I have been noticing that same lack of power when getting going, but furthermore, the truck is now taking probably 6-7 seconds of turning over to get it going (the prolonged turning over only seems to happen after it's been driven for a while and sits in the off position for about 10-15 minutes or so) I checked the fuel pressure at the rail and it's running about 83 psi or so which I understand is not normal, I also found that when it is taking forever to turn over, the fuel pressure will start out barely pushing about 5 psi or so and slowly move up to about 15-20 psi and then all of the sudden it shoots straight up to 80 once fired up. One other thing I have noticed is that my engine is taking quite a while to get up to temp, especially with the heat on.
    My code reader does not have live data, but when I pulled the code it displayed STFT at -3.1 % and LTFT at 23.4%

    So far what I've done:
    • Change fuel filter
    • Changed all spark plugs
    • Found oil on the two of the plugs so I changed the valve cover gasket
    • Intake manifold gasket kit for the plenum
    • I have ordered a new thermostat but it will be Monday before it gets here

    What should I do next?

    I was thinking maybe I have a bad fuel pressure regulator or pump but none of the stores had one in stock, and I also thought maybe I should change out my injectors to be safe also.

    Any help would be greatly appreciated

    Attached Files:

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  3. getbent

    getbent New Member

    Turning the heat on is like turning on another radiator to the engine. It will take longer to heat up as you are dumping heat into the cab. If you ever overheat in the summer, turn on your heater and that will help cool your engine somewhat.
  4. Juliofrancis

    Juliofrancis New Member

    Sounds like a multi-function problem. The ranger fuel pump is powered 2 ways. When the key is first turned on the pump is powered by a relay for two seconds. This is intended to charge and prime the fuel system to an operational pressure...60-70 psi. This relay turns off after 2 seconds. If the engine starts the crankcase position sensor informs the PCM (powertrain control module) the engine is running and the PCM then turns on the regular operating power circuit for the fuel pump. If the engine does not start the bypass feed shuts off and the pump is no longer powered. The pressure behaviour you are showing points to the initial relay feed not operating. Most likely the relay is the problem. Swap it with another in your fuse box to test. You can also bridge the connector slots the relay plugs into but unless you know your wiring....dont. You could fry the PCM. As to the higher than spec pressure....... someone else is going to have to address that.
  5. Tom Autry

    Tom Autry New Member

    Sounds to me like the fuel pressure regulator has gone bad !

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