V6 Won't Start - Fuel Pump?
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  1. #1
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    V6 Won't Start - Fuel Pump?

    Here's what I know:

    1. Starter motor cranks strong but engine doesn't start.
    2. Pulled one spark plug and verified I've got spark.
    3. No voltage at two outer pins of fuel pump connector at fuel pump.
    4. Pulled fuel pump relay - hooked up coil directly to battery, relay clicks and get continuity across pins 30-87 and 30-87a.
    5. Checked voltage at relay socket for coil - with ignition switch on, only about 8.5V. Wired that to relay coil and confirmed that is not enough voltage to close relay (no click).
    6. Plugged in jumper wire across relay socket pins 30-87 and get battery voltage at the two outer pins of the fuel pump connector.
    7. Tried to start car with relay jumper wire installed but no start. But I did not jumper relay pins 30-87a - does anyone know what that part of the relay does? Will the car run without that jumpered?

    Any thoughts of why the low voltage at the relay socket for the coil?

    Thanks in advance.

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  3. #2
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    Are you plugs wet after a bit of cranking?

  4. #3
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    I finally gave up and had it towed to my indy. A day later he goes out to the car, turns the key and it starts right up. He did a codes scan and declared it to have perfect health. Cost including tow $183.

    I suspect a marginal relay and may just go ahead and replace it.

  5. #4
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    i'm on the same page with that assumption, however the fuel pump is still suspect.

    a little trick with the chevies is when the fuel pump starts going out, it goes out sparatically. the failure is caused by the motor's contacts getting worn to a point they rattle and intermittently make contact on and off.
    the trick is you take a rubber mallet and whack the fuel tank from the bottom while they key is in the accessory position, where the fuel pump WOULD be running.

    if it comes on, you will hear a harmonious hum. if it doesn't, you just hear a resounding thud from the mallet, that's all.

    when you towed the car to your bud, the car got shaken quite a bit, didn't it?

    avoid long trips, and stay close to home with the car. it's entirely possible the fuel pump could be in early stages of failure.

    if it DOES die on you again, and you can get into safe parking (lot or gas station) get under there and give the gas tank a couple good whacks to see if that knocks the fuel pump back on.
    if you get stuck on the highway, and pull into the shoulder... just call a tow...
    risking your life isn't worth it compared to the minimal $80 for a tow and then the assurance that you will NOT be maimed in any way shape or form...

  6. #5
    PZ
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    Since the pump is mounted from the top, hitting the top would be more effective (and easier).

  7. #6
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    OK, it happened again - no start after doing fine for about a week. Next morning, started right up.

    Is there anything else involved in getting power to the fuel pump other than the relay? Any inertia or cutoff switch, or pressure switch involved?

    When its working, I can measure battery voltage at the outer two wires of the fuel pump electrical connector (after disconnecting it) for a couple of seconds only right after the ignition is switched on, and then it goes to zero. Does that make sense? Once again, the car runs fine when this is happening. I haven't checked this when it is not working to see what difference there may be - I will if/when it happens again.

    I've already replaced the relay - do I just go ahead and do the fuel pump? It's something like $250+

    Anything in the ECM that could be messing me up?

    HELP!!

  8. #7
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    I can measure battery voltage at the outer two wires of the fuel pump electrical connector (after disconnecting it) for a couple of seconds only right after the ignition is switched on, and then it goes to zero
    this is normal on all cars, the ECU pressurizes the fuel line in order for the engine to start.

    do I just go ahead and do the fuel pump? It's something like $250+
    i personally wouldnt espically until im FOR SURE that the fuel pump is bad

  9. #8
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    Quote Originally Posted by EuRoRaCeR View Post
    this is normal on all cars, the ECU pressurizes the fuel line in order for the engine to start.



    i personally wouldnt espically until im FOR SURE that the fuel pump is bad
    That is normal for the voltage to come on for a few seconds when the key turns on....crank it over voltage should be consistant.....fuel pump yes....how many miles?

  10. #9
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    Sounds more like a bad sensor to me and if I had to guess w/o quite enough info, I think the car is flooding on start up when warm. It cools off and the next time you try it has the right fuel/ air mix.

    If it was me, I would have the codes read, if any. You have already checked for spark so the next time it happens try putting the pedal on the floor and cranking a bit to see if it starts or pull a plug and see if it is wet.

  11. #10
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    Quote Originally Posted by uksparky View Post
    That is normal for the voltage to come on for a few seconds when the key turns on....crank it over voltage should be consistant.....fuel pump yes....how many miles?
    Good to know the few seconds of voltage is normal - thanks! I'll check for that next time it happens. 122k miles.

    KDXClarK: The car wasn't warm either of the two times it failed to start - first time it happened the car had been in the garage 24 hours.. Both times it happened, it fired immediately for a second or two, followed by what I think was a very brief "zap" sound, and then no fire, only crank. The first time it happened, I had the car for 3 days trying to start it several times before it was towed. The second time it happened in the evening after being parked 12 hours, it started immediately the next morning. My indy did a complete codes scan after he started it following the first event and saw nothing. He now suspects a problem with the fuel pump or the circuitry to it. Since I've replaced the relay, I don't think there's much left but the pump. I can get one from ECS 2 day shipped for less than $140 so I think that will be next.

  12. #11
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    Update: I ordered and installed the new fuel pump. I hope saying this doesn't come back to haunt me, but no starting problems for 2 weeks since installing the new pump. For a long time, I've had to crank the engine quite a bit to start it when it's warm - did the CTS thing and that didn't help. That seems to have corrected itself with the new pump too, so maybe the old pump had been struggling for some time.

  13. #12
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    There was a recall for the fuel pump replacement some time ago. You might want to check if your car was included in that recall. If so, you might get reimbursed by VW.

    Good luck, Peter

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