FYI FORD - MustangSteve's Ford Mustang Forum
The Internet's Most Knowledgeable Classic Mustang Information
IF YOU HAVE A QUESTION ABOUT CLASSIC FORD MUSTANGS, YOU HAVE COME TO THE RIGHT PLACE!
MustangSteve has over 30 years of Mustang experience, having owned 30 of them and restored several others. With the help of other Mustangers, this site is dedicated to helping anyone wanting to restore or modify their Mustang.... THERE ARE NO DUMB QUESTIONS!!!!!
Visit MustangSteve's web site to view some of my work and find details for:
FYIFORD Contributors' PICTURES - Power Brake Retrofit Kits for 65-66 Stangs - Classic Mustang FAQ's by MustangSteve - How to wire in a Duraspark Ignition - Mustang Ride Height Pictures and Descriptions - Steel Bushings to fit Granada Spindles to Mustang Tie Rods - Visit my EBAY store MustangSteve Performance - How to Install Granada Disc Brakes MustangSteve's Disc Brake Swap Page - FYIFORD Acronyms for guide to all the acronyms used on this page - FYIFORD Important information and upcoming events

You are not logged in. Would you like to login or register?

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  » Does Oil Pressure Switch control Fuel Pump?

    • 1 of 1

       

    6/24/2020 7:06 AM  #1

    TremendousWand
    I FYI 24-7

    Offline

    Registered: 5/16/2013
    Posts: 657

    Does Oil Pressure Switch control Fuel Pump?

    1966 Mustang Coupe, 5.0 Swap, T5z, EFI, MAF, GT40 Swap

    I'm trying to solve a rich fuel condition.  Checked all the spark plugs and they are covered in heavy soot.  Also got some smoke from exhaust and oil is black and sooty too after just changing it.

    Thought I had a valve stem seal issue causing the exhaust smoke, but now I'm not sure.  I don't have a wide band to measure actual AFR but it's obviously running rich from the spark plugs.


    -I have a holley adjustable fuel pressure regulator that I've never adjusted.  When running, fuel pressure is 40 PSI.
    -I removed the oil sender switch and replaced it with the wiring for my Dakota digital gauge.  I thought that the only purpose of this device was to read the oil pressure and send it to the gauge cluster.  I removed the switch and capped off the wire.
    -I haven't wired up the dakota digital panel.  I've only made the connections in the engine and ran the wires through the firewall.
    -In the KOEO the fuel pump now stays on.  It used to prime for about 2 seconds, now it just runs no stop.  
    -I can't get the OBD reader to run a test.  I connect it, do a KOEO but nothing it happens.  It used to go into test mode and spit out codes.  Tried two different readers, same thing.  Even the check engine light just stays dark.
    -Timing is set to 12 Deg BTDC.  Sounds ok, not great at idle.

    What can you make of this?


     

     

    6/24/2020 11:55 AM  #2

    Glens 1965 50
    FYI Addict

    Offline

    From: Tomball,Tx
    Registered: 4/01/2013
    Posts: 278

    Re: Does Oil Pressure Switch control Fuel Pump?

    The oil pressure switch does not go to the ecm and does not effect the computer.  Do you have access to another ECM?  Maybe swap the fuel pump relay It could be "Stuck" in the on position.  Does the fuel pressure remain 40 psi with the switch off.  It should hold for several minuets. Could have some bad injectors. Just food for thought.

     

    6/24/2020 11:59 AM  #3

    TremendousWand
    I FYI 24-7

    Offline

    Registered: 5/16/2013
    Posts: 657

    Re: Does Oil Pressure Switch control Fuel Pump?

    Glens 1965 50 wrote:

    The oil pressure switch does not go to the ecm and does not effect the computer. 

    I've been looking to confirm this but I haven't found anything saying the opposite.  What does the "switch" actually switch then?  I thought it might be tied to the fuel pump or ignition in some way where if it detected low oil pressure it would cut off.

       •Thread Starter
     

    6/24/2020 12:28 PM  #4

    Raymond_B
    Senior 24-7 FYI Addict

    Offline

    From: Fort Worth, TX
    Registered: 4/01/2013
    Posts: 1,208

    Re: Does Oil Pressure Switch control Fuel Pump?

    In that year there is no such thing as oil pressure "pretection", it's simply for the gauge. Even if it were some sort of low oil pressure safety system the fuel pump would not run all the time and you'd be able to pull codes.

    Do you have a chip or other tuning device? If so reseat it or remove it to see if that changes anything.

    Otherwise it sounds like you have a bad computer. Pretty common failure nowadays as these components are getting old. If you pull the computer out and then take apart the case you can spot "easy" fixes such as a popped capacitor.

    Last edited by Raymond_B (6/24/2020 12:28 PM)

     

    6/24/2020 2:06 PM  #5

    TremendousWand
    I FYI 24-7

    Offline

    Registered: 5/16/2013
    Posts: 657

    Re: Does Oil Pressure Switch control Fuel Pump?

    Raymond_B wrote:

    In that year there is no such thing as oil pressure "pretection", it's simply for the gauge. Even if it were some sort of low oil pressure safety system the fuel pump would not run all the time and you'd be able to pull codes.

    Do you have a chip or other tuning device? If so reseat it or remove it to see if that changes anything.

    Otherwise it sounds like you have a bad computer. Pretty common failure nowadays as these components are getting old. If you pull the computer out and then take apart the case you can spot "easy" fixes such as a popped capacitor.

    Yea need to check the ground on the ECM.  Painless guy said to test for power coming into CEL and check relays.  ECM do go bad, but this has been in the garage and was functioning.  
     

       •Thread Starter
     

    6/25/2020 5:27 PM  #6

    John Ha
    I FYI 24-7

    Offline

    From: Mitchell, SD
    Registered: 4/02/2013
    Posts: 932

    Re: Does Oil Pressure Switch control Fuel Pump?

    Wouldn't a leaking injector cause both the rich condition and a constant pump run?

    Founding Member of the Perpetually Bewildered Society
     

    6/25/2020 5:41 PM  #7

    Nos681
    Senior 24-7 FYI Addict

    Offline

    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
    Posts: 3,336

    Re: Does Oil Pressure Switch control Fuel Pump?

    If it was leaking that bad I’d be scared.😁

    I would check fuel pump relay and ecm.

    Does it continue to run with ignition turned off?  If so relay, or wiring to it possibly.

    Did you disconnect, connect, modify, move wiring before this occurred?
    Interior or engine compartment?
    May want to examine your wiring.

    Last edited by Nos681 (6/25/2020 5:47 PM)

     

    6/25/2020 5:44 PM  #8

    50vert
    Senior 24-7 FYI Addict

    Offline

    From: QLD Australia
    Registered: 4/01/2013
    Posts: 1,427

    Re: Does Oil Pressure Switch control Fuel Pump?

    Undo the wiring connections you made and see if it will then allow a KOEO test

    "Those telephone poles were like a picket fence"
     

     

    1 of 1

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  »  Does Oil Pressure Switch control Fuel Pump?

    • Board footera


    REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.