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98 S 10 Blazer starts but wont run!

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  • 98 S 10 Blazer starts but wont run!

    I need some help. My buddies 1998 S10 Blazer will not run. When you hit the key the engine turns over and starts normal but dies right away. It gets gas from the initial priming but that's it. It will do this all day long. The fuel pump was replaced 3 months ago, you can hear it running as soon as you turn the key on. We disconnected the fuel line after the filter and turned the key on, the fuel pump started and there was plenty of flow. We did this several times very quickly and the fuel flow was strong every time. If you spray starting fluid in the throttle body after it's started it will stay running so it is a fuel issue of some type. Is there a separate relay or pressure switch that controls the fuel pump once the engine is running? Could it be a wire in the ignition system? Any ideas will be greatly appreciated.

    Thanks

  • #2
    sounds like an anti-theft deal to me, does it have the diode key? That's classic PATS behavior. If the pump is bad I wouldn't expect it to start at all.

    I'm not sure on the GM's but Fords are a major bitch. Try one of your other keys in it.
    Last edited by Beagle; August 19, 2012, 08:38 PM.
    Flying south, with a flock of bird dogs.

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    • #3
      I would say low fuel pressure, you need to get to a mechanic and have them hook up the pressure gauge and that will tell the story.

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      • #4
        the 4.3 had a funky poppet spider injector setup that I've hear horror stories about, but I would think low fuel pressure it would have gotten progressively crappy... the schrader is up high and easy to get to. You can get a guage from Autozone and check it, pretty sure it should be 40 ish.

        The reason I say PATS is they will let the car start, run for couple seconds, turn the pump off if I remember that correctly. Also could be crank position sender or ckp not sending an rpm signal that it's running, but I'm not sure how that translates to runs on starter fluid.
        Flying south, with a flock of bird dogs.

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        • #5
          5 seconds sounds like Passlock system problems. I have a 98 Malibu that has sporadic issues. Take the key out and dont try to start it for 10 minutes and it resets itself, then goes around a month before it gets bitchy again. 97 was the last diode key Beagle, 98 started with regular keys and the system identifying the key when it engages.

          You should have an anti theft light or security system on the dash if it is though. If its a fuel delivery or fuel pressure deal, the MAP sensor is what controls the regulator, so if you are losing vacuum there (the tubes crack off real easy) you wont have the correct fuel pressure to control the regulator. you can put a little hand vacuum pump on the regulator and draw a vacuum to see if it will keep running with proper vacuum at the regulator. We had 40 psi with around 12 pounds of vacuum.

          As far as the crank sensors, you have on behind the balancer and one in the center of the crank, it just takes one skipped signal at either one to kill the spark, but pretty sure he would still be getting fuel.

          Sure sounds like a Passlock issue since that just deals with shutting off the fuel.
          Last edited by anotheridiot; August 20, 2012, 05:56 AM.

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          • #6
            Thanks for the help. I had limited tools when I looked at it the other night but I did see the schrader valve. I will get a gauge and test the pressure. When you start the engine it shuts off almost as soon as you release the key to the run position. How long does the passlock system allow the vehicle to run? I know very little about this cars past (a friend of a friend) but I did find out that this problem has come and gone for a while but has always gone away after a few attempts to start it, but not this time.

            Thanks again

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            • #7
              i would look into the poppet valve issues as beagle suggested... we had nightmares with them until we did the retrofit that replaced the poppets with injectors turning it into a real multi port fuel injection rather than center port... runs great now!

              Motor Man Fuel Injection offers OE CSFI to MFI conversion Spider Injector systems for 1996 and up GM 4.3L 5.0L 5.7L Vortec engines
              Last edited by silver_bullet; August 20, 2012, 06:49 PM.
              Patrick & Tammy
              - Long Haulin' 2008, 2009, 2010, 2011, 2012, 2014...Addicting isn't it...??

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              • #8
                Could also be the regular. This would also cause low fuel pressure.
                Previously HoosierL98GTA

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                • #9
                  Originally posted by R442 View Post
                  Thanks for the help. I had limited tools when I looked at it the other night but I did see the schrader valve. I will get a gauge and test the pressure. When you start the engine it shuts off almost as soon as you release the key to the run position. How long does the passlock system allow the vehicle to run? I know very little about this cars past (a friend of a friend) but I did find out that this problem has come and gone for a while but has always gone away after a few attempts to start it, but not this time.

                  Thanks again
                  no more than 5 seconds, but you should see a security lite on the dash somewhere.

                  PASSLOCK

                  The Passlock system is designed to prevent vehicle operation if the key is not used to start the vehicle. The key, which does not contain a resistor will turn the Passlock lock cylinder. The Passlock lock cylinder will relay a resistance code to the instrument panel cluster (IPC). It does this by rotating a magnet past a stationary hall effect sensor, creating a resistance code. At this point the IPC will determine if the resistance code is correct and within an acceptable time frame. If the code is correct, the IPC will send a coded password to the powertrain control module (PCM). If the PCM receives the correct password, it will allow the fuel injectors to operate normally and the vehicle will start and run normally. If the correct resistance code from the lock cylinder is not received within the acceptable time frame, the vehicle will go into a short tamper mode during which the theft deterrent system will not allow the vehicle to operate for approximately 4 seconds. When this occurs, the security indicator will flash. After three consecutive failed tries, the system will enter into a long tamper mode. In this mode, the fuel injectors will be disabled for approximately 10 minutes, and the security indicator will be flashing. Please note that in any of the tamper modes, the vehicle may start, but it will quickly stall.

                  Default
                  The Passlock system is designed to prevent vehicle theft even if any of the theft deterrent parts are replaced. Passlock eliminates the need for the key mounted resistor. Parts that can no longer be replaced without the possibility of the system going into a tamper mode and prevent starting are: the lock cylinder, the instrument panel cluster (IPC), and the powertrain control module (PCM).

                  In order to initiate the relearn:

                  1. Hook up your scan tool to erase any of the passlock/vehicle theft deterrent trouble codes. If there are any other codes, note them before you erase them, so you may address them after the relearn has been completed.
                  2. With the ignition key in the “On” position from the code-clearing step, attempt to start the vehicle. At this point, if the vehicle starts, and the security light has not illuminated, a relearn is not necessary, and you’re done. If the vehicle starts and stalls, leave the key in the “Run” position and wait for the “Security” light to turn off. This will take approximately 10 minutes. At any time during this relearn, the light may flash or be on steady. If the ignition switch is turned off at any time during this relearn cycle that the security light is illuminated, the entire cycle must be restarted from the beginning. For most cars, one cycle will be sufficient for the relearn. If the vehicle will not start after the first cycle, then continue the process from step #3 to the end. Most trucks will require that you continue from step #3 to the end.
                  3. When the light turns off, turn the ignition switch to the “Off” position for approximately ten seconds.
                  4. Next, repeat steps 2 and 3 two more times for a total of three cycles. After the third time, the new code will be relearned on the next start attempt when the ignition switch is rotated from the “Off” position.
                  5. From the “Off” position, start the vehicle, observing the security light. If the vehicle starts and runs normally, and the security light is off, the relearn is complete. If the vehicle does not start, check for trouble codes before proceeding further.

                  You can search Passlock 2 bypass to get the procedure to put a hidden toggle switch to the yellow wire,

                  If you dont see that security lite, then you need to check the map sensor, regulator and fuel system, but the way it sounds it is not just a fuel delivery problem, even though there are bad fuel pumps out there.

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                  • #10
                    I'm with the Idiot (had to do it) on the passlock. If it's the F/I spider, it will run, just real bad and throw codes.
                    Whiskey for my men ... and beer for their horses!

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