you guys tell me

Discussion in 'Fox 5.0 Mustang Tech' started by 5pointohmustang, Dec 5, 2011.

  1. So I have read different readings from a variety of forums also with different years and all kind of stipulations. So With my specific info can you tell me if my fuel pressure readings are normal?
    1987 gt vert
    Only bbk intake (no MAF), msd ignition coil, wires, and rotor cap.
    Other than that its stock, Ive never replaced the fuel pump, injectors or regulator Im not sure if they were ever replaced. There is a new fuel filter.
    So KOEO roughly 31 psi | with the vac line removed from the FPR 40 psi
    KOER 35 psi | with vac line removed from the FPR 45 psi
    I still have this power loss issue so if these readings are correct I guess I’ll be checking the timing this weekend and if the timing is good I will kill everybody hahahahahahahahahahahaa aaaa -____-
    Could my tranny be causing a power loss issue? I don’t believe its slipping but then again I wouldn’t know what that feels like…
  2. Fuel pressure like that shouldn't cause your problems, although 45 running with the vac line off (and plugged at the source!) is a bit high.

    Tranny slip is pretty obvious. Slip will allow an increase in rpm without a corresponding movement of the vehicle. But tranny slip won't cause the engine to run bad, unless the tranny is binding up so badly that the engine can barely pull the car.
  3. thanks, this is how my car is running can this be the cause of the tranny?

  4. I doubt it. Have you done a compression check?
  5. nope, maybe i should check that before the timing?
  6. Go ahead and do the timing and check compression. Only take an afternoon, if that long. Make sure you've done all the tuneup stuff, pull the codes, make sure there's no vac leaks...
  7. I just realized you have several threads going on the same thing. Not very good forum etiquette, and certainly has broken up all the discussions.
  8. sorry, just trying to get all the info i can
  9. Fuel pressure reading are normal for the conditions you specified, but may not be normal under load; i.e. what is fuel pressure at WOT?
  10. Thanks I haven't checked when I do, do I just floor it in neutral? What should be the correct reading when I do?
  11. Take the car for a drive and watch the fuel pressure gauge as you get on it. It should stay fairly consistent. If it has a significant drop then I would say you have a failing pump or a very bad fuel filter.
  12. thanks, I'm guessing you guys have the gauge that's mounted to the dash lol I don't see how I can watch the gauge and drive
  13. I don't have a fuel pressure gauge mounted, I used an extension hose on my mechanical gauge and let it sit on my cowl while driving
  14. Dump the codes: may be present even if the Check Engine Light (CEL) isn't on.

    Dumping the computer diagnostic codes on 86-95 Mustangs

    Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

    Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

    Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

    Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

    Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
    Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.



    If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.


    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

    89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.


    The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

    WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

    What to expect:
    You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

    Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

    Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

    Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

    Alternate methods:
    For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

    Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

    Attached Files:

  15. thank you sir, i already pulled the codes and its all egr related KOER 33,44,94 i have broken vac lines and im having trouble finding exactly where they go even after reading all the diagrams... so i know that's an issue but it shouldn't be causing the severe power loss i have.

    Attached Files:

  16. ok cool i'll try that hopefully before the weekend.