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Thread: Electrical issues

  1. #1
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    Default Electrical issues

    Hi guys..I Haven't been on here for a while.
    I'm having some kind of issue with the electrical in my 88 TC.
    About a month ago I drove car to work..when I cut car off I noticed fuel pump was still on..this blowed my mind considering that the key to car was out of switch and in my hand.
    So I put key back in switch turned switch on and then back off and fuel pump shut off.
    That's the only way to get the pump to shut off.
    I've also noticed my gauges also acting crazy and car isn't running quite right.
    I can have car running(not driving it) and I can run the rpms up to 2000+rpms and the speedo is running around 20-30mph and I'm sitting still.
    I've been driving around B4 and watch my temp,oil,and fuel gauge jump up to Max and then come back down within a few minutes.
    The speedo also sometimes jumps up when I roll my windows up and down.. pretty much about anything I do inside the car will make the speedo jump up.
    I've read that this is a common problem with these cars.
    As far as running goes..when I 1st crank car it dies..I might have to crank it twice B4 it starts up and runs without stalling.
    It will start but it bucks fusses and complains for alittle bit and then it will smooth out.
    That has recently started to..I'm wondering if the electrical problem is causing that too.
    Then yesterday I drove car it was doing it's normal thing..then when I pulled into my driveway the car was barely idling at 400-500rpm.
    Ive had ignition module issues which I've replaced about 6 of them since I've own car.
    I changed the ignition switch..using an on switch..that didn't change anything.
    I just don't know what to do anymore.
    Any suggestions would be helpful
    Thanks

  2. #2
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    Quote Originally Posted by wpblackfoxturbo View Post
    I changed the ignition switch..using an on switch..that didn't change anything.
    Please explain what you mean by "using an on switch" .

  3. #3
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    Did you replace this switch?
    Attached Images Attached Images

  4. #4
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    Quote Originally Posted by softtouch View Post
    Please explain what you mean by "using an on switch" .
    OEM switch

  5. #5
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    Quote Originally Posted by softtouch View Post
    Did you replace this switch?
    Yes..that's the switch I replaced

  6. #6
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    Default

    has anyone ever.............

    1- fiddled with the fuel pump relay in the trunk to force the pump to run?

    2- did a 3g alt upgrade

    3- had the instrument cluster out


    comment- there is a large resistor on the back of your instrument cluster.
    -remove the cluster
    -go to lowes and buy a stick of "soap stone". this is what welders use to mark metal. its about 3/16'' thick, about 7/16'' wide and about 5'' long.
    -cut soap stone to length of the instrument cluster resistor (big white skinny doo dad bolted to the back).
    -inspect the instrument cluster flex print for burn marks or any runs that are busted then repair if needed.
    -use a round chainsaw file longways along the soap stone to transfer in a groove that matches somewhat the profile of the skinny resistor.
    - loosen up or remove the resistor
    -slip the soap stone under the resistor
    -tighten down the resistor.

    Now all heat generated from the resistor will not make it to our fragile plastic flex print.

    this mod cured my son's 5.0L 88 bird erratic gauge issues


    in all likelihood, it sounds to me like you may have two separate isolated problems....

  7. #7
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    Thanks jcassity
    No on has messed with the fuel pump relay and if I recall the fuel runs off that black box that looks like a computers mounted to the right side strut tower.
    I had had the instrument cluster out.
    It had been taken out B4.
    The last time I had it out..was about a year or so ago.
    I did notice when I had cluster out that there was a black wire coming out of harness that wasn't hooked to anything and I couldn't find a black wire anywhere to reattach

  8. #8
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    You are right, your fuel pump relay is in the IRCM module on the strut tower. The EEC power relay is also in the IRCM.
    There two ways the fuel pump relay should de-energize:
    1. The EEC recognizes the engine is not running and removes the ground from the fuel pump relay coil.
    2. The EEC power relay de-energizes and removes the power to the fuel pump relay coil.
    The EEC power relay should de-energize when you turn the key off.

    If fuel pump problem happens all the time, or frequently enough to trouble shoot, try this:
    1. Turn the key to RUN but don't start the engine:
    2. Does the pump run for 2 seconds then shut off?
    3. Probe one of the red wires that go to all the fuel injectors. Should have battery voltage.
    4. Turn the key off. After a 5 second delay you should lose the power on the injectors.

    If the problem is intermittent, try this sequence several times to see if you can catch the power not shutting off to the injectors.
    This would indicate that the EEC power relay is not de-energizing when you turn the key off.
    Last edited by softtouch; 05-14-2018 at 12:56 PM.

  9. #9
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    Ok thanks.
    When I turn my switch on..the fuel pump runs then shuts off like normal.
    There has been a couple of times the fuel pump did turn off when I turned off switch but most of the time it stays on.
    Could the ignition module cause some of them issue.
    Just wondering because I just recently had to change module..then this happened the same day I changed it

  10. #10
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    The TFI ignition module does generate the PIP pulse to the EEC to indicate that the engine is running. I guess when electronic things go crazy anything is possible.
    Still would like to know if the EEC power relay is dropping power to the injectors when the key is off.

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