Start / No-Start Issues with my 95 Deville
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Start / No-Start Issues with my 95 Deville in Past Cadillac Vehicle Discussion; ...
  1. #1
    sick467's Avatar
    sick467 is offline Cadillac Owners Member
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    Start / No-Start Issues with my 95 Deville

    Hello, new to the forum, 5 year Cadillac owner - 1995 Sedan Deville 4.9.

    Been hanging out at another Cadillac site, but the attendance seemed weak there and I had to jump ship.

    I have been having intermittent starting troubles. When a no-start occurs, there is no fuel pressure at the check valve (the tire-like valve near the fuel line under the hood). If I put a test light on the connection for the fuel pump relay (with the relay removed) I get a momentary signal once the key is turned to the “on” position - like I should. If I put the relay back in and disconnect the fuel filter NO fuel comes out during this momentary signal. If I remove the horn relay and the fuel pump relay and jumper some power from the horn terminals to the fuel pump, the pump will power up and push fuel. With the fuel filter re-connected and the jumper in place, the car will start and run properly. I can quickly remove the jumper and reinsert the fuel pump relay and the car runs just fine and will shut off with the key and even restart properly (sometimes) and then it’s back to not starting. The jumper trick will bring it back to life, but it may act normal for days/weeks or not start the next time it is attempted. At least the recently discovered jumper trick avoids a tow - I've had it towed for this problem twice in the last few months!

    Any ideas here? I think the trouble must be upstream from the relay or the jumper trick would not work. Thanks in advance!

    PS: I have changed the fuel filter (just in case) and tried starting the car during a "no-start" moment with the gas cap off. I have also swapped relays around to no avail.

    Ride On,

    Noel

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  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: Start / No-Start Issues with my 95 Deville



    Have you tried replacing the fuel pump relay?

    P.S.
    I too jumped ship over there for the same reasons (and a few others).

  4. #3
    sick467's Avatar
    sick467 is offline Cadillac Owners Member
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    Re: Start / No-Start Issues with my 95 Deville

    The first time it happened I took it to a shop (normally I work on my own cars, but I was in the middle of a move and had nowhere but the hotel parking lot to work). The shop had it for a week and could not find the problem, but did replace the relay with a new one (back in 2012). I have since swapped relays between the horn and the fuel pump and the horn will work with either relay and, up until lately, the fuel pump would work with either.

  5. #4
    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
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    Corrosion in the relay socket? A loose connection to the socket itself?

  6. #5
    basscatt's Avatar
    basscatt is online now Cadillac Owners 10000+ Posts
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    Re: Start / No-Start Issues with my 95 Deville

    Quote Originally Posted by sick467 View Post
    The first time it happened I took it to a shop (normally I work on my own cars, but I was in the middle of a move and had nowhere but the hotel parking lot to work). The shop had it for a week and could not find the problem, but did replace the relay with a new one (back in 2012). I have since swapped relays between the horn and the fuel pump and the horn will work with either relay and, up until lately, the fuel pump would work with either.
    -------------------
    almost sounds like a "SECURITY" issue - shutting down the fuel pump -

    have you checked for codes?

  7. #6
    MoistCabbage's Avatar
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    VATS would disable the starter as well.

  8. #7
    sick467's Avatar
    sick467 is offline Cadillac Owners Member
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    Re: Start / No-Start Issues with my 95 Deville

    I have in the recent past and will check for loose terminals and corrsion again tonight.

    And the only applicable code I got was the PO20 code for "Open Fuel Pump Circuit" which I have figured was the problem. Other codes are for the tranny convertor clutch (a bad sensor I think - the tranny works wonderfully), Left and right Oxygen Sensor signal Rich, PCM Memory Reset, Loss of Road Sensing Suspenion Data (the infamous bad sensor in the rear suspension),Keep Alive Memory Error, and that's it.

    I am also going to put a check light on the pump relay to verify that I get a full signal to the pump while cranking. I suspect that it is not there otherwise I should get a delayed start not a No-Start.

    One question: Is there afuel pressure switch that controls the power to the fuel pump or is it controled merely with a bypass back to the fuel tank?

  9. #8
    sick467's Avatar
    sick467 is offline Cadillac Owners Member
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    Re: Start / No-Start Issues with my 95 Deville

    the funniest thing. I just got home and tried to start the car and it started fine(its normal hit and misses tendency). I pulled into the shop and pulled the relay for the fuel pump. Put a test light in the power supply for the fuel pump relay turn the ignition and got a momentary light as expected. Then I tried to start the car it started and idled fine without the fuel pump relay. I then shut it off, relieved the fuel line pressure at the fuel rail valve and tried again. It started after a delayed moment and is still idlig fine. I would have never thought it would start without the fuel relay?????? And it revs up fine too!

    Oh the mystery grows!!!

  10. #9
    Ranger's Avatar
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    Re: Start / No-Start Issues with my 95 Deville

    Fuel pressure is controlled by the FPR. Unused fuel is routed back to the tank.

    ----------

    Sometimes when the fuel pump starts to go, it draws a lot of amps and burns the contacts in the connector causing an intermittent condition. Have you checked the connector?

  11. #10
    sick467's Avatar
    sick467 is offline Cadillac Owners Member
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    Re: Start / No-Start Issues with my 95 Deville

    I have inspected the connection at the fuel tank and it appears to be fine, and when I jumper power at the relay with a paper clip the no-start senario vanishes and it starts and runs fine. So, I beleive the problem is upstream from the relay. But the fact that it will sometimes start without the relay in place really confuses me. It must have an electircal bypass that is computer controlled.

    ??????????????????????

    I hate to rig up some wiring and a switch to bandaid the situation. It just seems sacrilege to do that to a Cadillac.

  12. #11
    Ranger's Avatar
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    Re: Start / No-Start Issues with my 95 Deville

    Sure sounds like a bad relay, but if not that, maybe the ignition switch (not the tumbler, but the switch on the column)? It IS old with a LOT of use.

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