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Stalls then won't start till fuel relay reset?

omgitsunknownomgitsunknown Member Posts: 12
edited March 2018 in Pontiac
So I have a pontiac G6 4 cylinder that has had the fuel pump changed multiple times. I recently took it the dealer they said thwy couldn't find anything wrong with it. I told them to fill the car up with gas because thats normally when it happens they said they did, but when I got it back it still had half a tank. So I went by the gas station and filled it up. As I went to leave the gas station it stalled as I pulled out into the intersection. I pushed it back into the gas station parking lot and called the dealer back. I got it back over there and they changed out the fuel relay its been about a week now and my car isn't starting now fuel pump is kicking on but I'm back to square one. Any ideas? I'm lost and apparently no one has had this issue...
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  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    edited March 2018
    Well it has to be diagnosed by someone who knows what to look for. If there's a no start, they have to determine what is being "lost"--is fuel getting up to the fuel rail? Is there spark? Are the injectors opening? Is there compression?

    This shouldn't be too hard for a good mechanic, especially since the problem seems to be in permanent fault at the moment.

    If you are at a loss for a good technician, you might try THIS WEBSITE---just click on repair shops and see if there's someone near you, or close enough to be towed economically. These technicians are all well-trained.

    http://www.iatn.net/
  • omgitsunknownomgitsunknown Member Posts: 12
    I understand this as I know what to look for it's just that everytime it has become something different. Originally it was a bad fuel pump changed that then there was no pressure fixed that. Car was good for about a week now back to it being intermittently working. If I take out the relay and put it back in it works just fine until it hits a point and either causes the relay to stick open or just not allowing the fuel pump to work properly.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    edited March 2018
    Oh you said the fuel pump wasn't working at all. So sometimes it works and sometimes it doesn't? Or does the fuel pump relay just die and stay dead, time and time again?

    I think you need to dig a bit deeper here and determine if, during the no start, one of the following is happening:

    1. The fuel pump doesn't work but the fuel pump relay is energized and working.
    2. The fuel pump doesn't work AND the fuel pump relay is not energized
    3. The fuel pump and fuel pump relay both bench test perfectly but sometimes the circuit is not energized



  • imidazol97imidazol97 Member Posts: 27,595
    edited March 2018
    X2 on Mr. Shiftright's suggestions that it needs a reputable mechanic to troubleshoot it logically.

    I understand that you are saying the fuel pump now turns on when key is turned and runs for about 1 second to build pressure. Then turns off. Normal.

    And you are saying the car won't start, even though it would appear to have fuel because of the fuel pump's having just run.

    How do you eventually get the car started?

    I am not a mechanic but have worked on cars for myself for decades. I have read forums and problems people have had with their H-body leSabres and Bonnevilles since 1993 or so. And have read about Malibus and problems since 2013. Somewhere there was a problem with the car related to filling up the gas tank and something happening that I recall. If I find something that's related, I'll post it back here. I just don't recall which series of cars it's related to.

    EDIT: Don't throw parts at this problem. Get it diagnosed. But if you have filled up and it won't start try pushing the gas pedal to the floor and holding it wide open while cranking. This turns off the injectors and clears fuel vapors just like for a flooded engine. If that works, you have another clue, not a diagnosis... Some people say a faulty vapor recovery system on the tank can cause fumes to get into the intake and essentially flood the engine.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • omgitsunknownomgitsunknown Member Posts: 12
    It's intermittent the car will go for a week then you'll normally fill it up with gas and then as your leaving the gas station it will stall. Sometimes if you let it sit it will start back up, but if you take the relay out and put it back in it seems to reset the system because it will start right back up after that. 
  • omgitsunknownomgitsunknown Member Posts: 12
    The fuel pump will run sometimes but not constant because it is building the pressure needed. 
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    OK, so we know this for sure?

    That, when the car stalls, it won't restart (sometimes) but it WILL restart every single time you pull out and put back in the fuel pump relay?

    Or is that "iffy" as well?

  • omgitsunknownomgitsunknown Member Posts: 12
    More so then not normally. About 9 times out of 10 it will start I'd say. 
  • omgitsunknownomgitsunknown Member Posts: 12
    I get more fine details once I'm with the vehicle  
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Well that's where hands-on diagnostics is so important, and a scan tool pretty essential. I think you have some kind of "ghost" in the electrical system and that's why you can't pin it down to one single thing that can be isolated with one single test.

    I think you need a good wiring diagram and you have to test all along this entire circuit.
  • omgitsunknownomgitsunknown Member Posts: 12
    Yeah that's what I have come to the conclusion of as well. Not looking forward to it so far. 
  • imidazol97imidazol97 Member Posts: 27,595
    edited March 2018
    Now I'm even more confused as to what the symptoms are. I was following the idea it would stall soon after starting after filling the tank with fuel.

    Remember that the fuel pump is energized for only a long second after the key is turned to ON, then it turns off until the key is again rotated. Don't get fooled during the troubleshooting that the pump isn't working all the time while the key is ON.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • omgitsunknownomgitsunknown Member Posts: 12
    So I just got done looking at my car. When I got to it all it did was crank. Then I unplugged the fuel pump relay plugged it back and it started right up I had a fuel pressure gauge hooked up and I was reading with car on engine off around 60 psi then progressively dropped. I started the car and it ran just fine. Now the pressure gauge is reading erratically between 50 and 60 psi. If I gave it gas up to about 3000 rpms it would stabilize at about 60 psi steady. Now it will not start again after letting it idle for about 20 minutes. I shut it off and let the pressure out of the pressure gauge and now I turned the key back on engine off and it isn't rebuilding pressure. So I unplugged the relay and plugged it back in again, but now that is not working so I'm not sure if something is overheating or if it is going into a safety mode which is causing the car to automatically shut off the fuel pump. 
  • imidazol97imidazol97 Member Posts: 27,595
    edited March 2018
    Leak down pressure drop could be injector leaking fuel into intake manifold when pump is off.
    Leak down pressure drop could be defective fuel pump not holding pressure.

    When you turn the key on, do you hear the fuel pump run for a second or two? May need someone with
    ear at filler opening to listen unless in a quiet area.

    Were any check engine lights on? Any codes?

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • omgitsunknownomgitsunknown Member Posts: 12
    Only time I got a code is when I took the relay out and put it back in and that was P0320. For fuel pump wiring something. OK so it's morning tried starting it and nothing just cranking fuel pump is not humming tried reseting the relay and nothing so is that relay dead?
  • omgitsunknownomgitsunknown Member Posts: 12
    Would a leaking injector cause this issue though?
  • omgitsunknownomgitsunknown Member Posts: 12
    Also what if I were to put in a switch for the fuel pump and just bypass the relay. make a switch with a in line fuse?
  • omgitsunknownomgitsunknown Member Posts: 12
    Or what pins of the relay can I jump just to see if thats it? It's a  4 pin relay
  • imidazol97imidazol97 Member Posts: 27,595
    edited March 2018
    Inspect the wiring from the fuel pump at the connectors with corrosion and all along for areas rubbed and shorting .

    See if there's another relay in the relay/fuse center that's the same part number that can be interchanged to see if the fuel system functions correctly.

    A leaking injector can cause retained pressure in the rail to drop and puts extra fuel into the intake manifold causing flooding...

    You may have multiple problems. You may just have a bad fuel pump that's letting fuel pressure leak out when off. What brand did you put in?

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • thecardoc3thecardoc3 Member Posts: 5,840
    omgitsunknown said:

    Also what if I were to put in a switch for the fuel pump and just bypass the relay. make a switch with a in line fuse?

    Let's assume that works so you leave it that way. The system is designed to shut the fuel supply off if the engine isn't running. If someone would get into an accident in the future and the car develop a fuel leak and they for whatever reason cannot shut the fuel off, well.......

    A leaking injector would generally cause a single cylinder misfire on top of the other symptoms.

    Shiftright and Imidazol have been doing fine advising you, they only way they could do more would be to show up at your house and test what they know how to themselves. Diagnosing this problem is very straight forward but it starts with one key point, forget everything you know about it from the past and test and prove what it is doing right now. Do not assume the no-start right now has anything to do with any previous work. When someone assumes that the current problem is related to past issues, or especially to what happened with someone else's car that is a trap and they can end up wasting a lot of time and money tossing parts that werent proven to be defective.

    At this point your fuel pump is not turning on, correct? Do you have a schematic for the fuel pump control circuit?
  • thecardoc3thecardoc3 Member Posts: 5,840
    imidazol97 said:

    Somewhere there was a problem with the car related to filling up the gas tank and something happening that I recall. If I find something that's related, I'll post it back here. I just don't recall which series of cars it's related to.

    That occurs if the cannister purge valve has failed and is stuck open. Air and fuel vapors are forced from the tank during refueling, they are supposed to exit through the cannister assembly which allows the air to pass through while it traps the fuel vapors from the tank. When the purge valve sticks open, some of the fuel vapors are forced into the intake manifold and air cleaner which on top of the injectors feeding fuel when attempting the restart results in a fuel mixture inside the the engine that is too rich to fire. By using clear flood mode (holding the throttle down while cranking) you shut the injectors off and that leans the air/fuel ratio allowing the engine to start.
  • thecardoc3thecardoc3 Member Posts: 5,840
    Here is the schematic for the fuel pump and relay. The PCM puts a 12v command out to the relay on the DK-Green/White wire to turn the pump on. If you aren't hearing the relay click with turning the key to ignition on, (no crank) and then click to turn back off after about two seconds then the problem is on the command side of the relay.


  • NatebrokeitNatebrokeit Member Posts: 1
    I have the same issue. I'm going to replace my fuel pump.
    Any final solution here?
    Also, I want to replace the wiring harness my fuel pump plugs into. I think it's in bad shape.
    Can this be bought? I can't find it anywhere. Looks like it leads to the relay in the trunk.
    Thank you!
    2007 Pontiac G6
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