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1998 K1500 Vortec 350 starts and dies

This is a discussion on 1998 K1500 Vortec 350 starts and dies within the Technical / Maintenance forums, part of the General Discussion category; It's my neighbor's truck. He drove it to town and back home, Came out next day, it will start but ...

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    1998 K1500 Vortec 350 starts and dies


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    It's my neighbor's truck. He drove it to town and back home, Came out next day, it will start but immediately dies. It has been like this for months now, and we still do not have it running. We are going to get back on it again, now.

    There are no codes. The check engine light was on when it was running, but he had disconnected the battery way back before I started working on it. Codes are gone, if any were there to start with. It has not recoded in our start attempts. We did hook up a scanner for grins -- nada.

    Here are the exact symptoms, with data we have found:

    1.) Key turned to first position (ON), fuel pump runs (confirmed), gauge at plenum port shows 65 psi. (This pressure will hold as long as a starting attempt is not made, so check valve is fine.)

    2. Turn key to START, engine starts up and immediately dies, rail pressure falls to nothing. Fuel pump does NOT run (confirmed).

    So what I am saying is that the fuel pump runs for the initial phase, but does not continue to run after that. This may sound like I am beating a dead horse to state the obvious, but guys at other forums have not been able to pick up on this. This is the problem, the pump will not run past initial pressurization.

    What we have tried:

    1. Tested spark. Hot and blue. No probs there.

    2. Replaced fuel filter.

    3. Bench-tested relay. It works (and if it didn't the pump would not start for initial pressurization).

    3. Replaced oil pressure sending unit. (You can crank the engine and it does show fine oil pressure on the gauge inside the cab on that initial short startup.)

    4. Plugged up a borrowed Chevy dealer test ignition switch, same start and die symptoms. Probably not the switch.

    Here is what I want to do. I want to jumper the fuel pump all the way to the battery, to see if it starts and runs that way. That would eliminate the pump, spider and injector wiring, as well as the ignition (which is cleared anyway by our testing), if it runs that way. Then the issue comes down to perhaps a wiring fault between the pump and battery.

    The reason I am posting is, he has a guy wanting to sell him an injector spider off another Vortec that the guy says works perfectly. The guy wants $100, and he is saying this is the problem. Personally, I do not in any way see how a defective regulator or spider assembly could cause the fuel pump to not run for the RUN segment of the startup sequence. I think he'd be throwing his money away, and he does not have it to toss away.

    I have had people at GM headquarters tell me it is the security system, serviceable only by a dealer. If it is that, I will find a way to hotwire around it. Other mechanics have said the ignition switches fail to send a confirmation signal to the ECM. Using the replacement tester would seem to have eliminated that.

    Someone else suggested the crank position sensor. Does that have anything to do with the fuel pump not starting on a Chevy after initial pressurization? It doesn't on the other stuff I have worked on, but I want to be sure here.

    ALL suggestions appreciated. If I plug in this problem to Google, I get all kinds of people asking this exact same thing, but no satisfactory answers that would lead me to be able to diagnose and fix this truck. Hope you all can remedy that.

    Thank you for your help in advance.

  2. #2
    Registered User diamondstealth's Avatar
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    Re: 1998 K1500 Vortec 350 starts and dies

    Sounds like VATS, had the same issue in my camaro. It was the ignition switch/key.
    1997 GMC K1500 XC 9in 35's
    1990 GMC K1500 406, Predator Carb, 5Spd 32's

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    Re: 1998 K1500 Vortec 350 starts and dies

    Was it exactly the symptoms I have described? If so, I will order a new switch and key.

    Why wouldn't my tester ignition switch/harness have worked, then?
    Last edited by jswordy; 10-28-2009 at 01:57 PM.

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    Registered User diamondstealth's Avatar
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    Re: 1998 K1500 Vortec 350 starts and dies

    Did you plug in the VATS wire on the new switch and make sure the resistance matched the old key/switch?
    1997 GMC K1500 XC 9in 35's
    1990 GMC K1500 406, Predator Carb, 5Spd 32's

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    Registered User diamondstealth's Avatar
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    Re: 1998 K1500 Vortec 350 starts and dies

    The VATS wire is extremely small, very delicate. The plug is usually on top of the steering column. Yellow wire.
    Last edited by diamondstealth; 10-28-2009 at 02:05 PM.
    1997 GMC K1500 XC 9in 35's
    1990 GMC K1500 406, Predator Carb, 5Spd 32's

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    Re: 1998 K1500 Vortec 350 starts and dies

    I get that. Tester switch might not have matched his truck's system. I did plug in all wires.

    What would happen if he used his other key, which is new? His sister has it in her possession. Might that make it work, and narrow the problem down?

    Is there a way to test this without buying new parts and trying them?

    Deal is, this guy is dirt poor, and I am trying to help him diagnose it without making him buy a bunch of parts to throw at it first.
    Last edited by jswordy; 10-28-2009 at 02:08 PM.

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    Registered User diamondstealth's Avatar
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    Re: 1998 K1500 Vortec 350 starts and dies

    His spare key should match in resistance to his old key, so Yes its a good idea to try that first.
    1997 GMC K1500 XC 9in 35's
    1990 GMC K1500 406, Predator Carb, 5Spd 32's

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    Re: 1998 K1500 Vortec 350 starts and dies

    Check fuel pump relay

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    Re: 1998 K1500 Vortec 350 starts and dies

    Fuel pump relay has been checked, as I said. Checked for operation and continuity. Passed.

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    Re: 1998 K1500 Vortec 350 starts and dies

    diamondstealth, I want to be clear about what you are telling me. I will need to get BOTH the switch assembly and the tumbler assembly (where the key fits into) replaced to correct the problem? All I had from the dealer as a tester was the swtich itself, NOT the tumbler. I turned the tester switch with a screwdriver, which is what they told me they do to test.

    THANKS. Sorry for all the ???, but I feel I am finally getting somewhere, maybe.

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    Re: 1998 K1500 Vortec 350 starts and dies

    The ignition switch assembly, but it has to be matched to his VIN, or else it will make no difference. Try the other key first. I just copied this from Google:

    "It is common for the leaf contacts and/or the resistor pellet on the key bow to become contaminated to the point where the VATS decoder module cannot correctly sense the pellet resistance, or cannot sense any resistance at all. This would usually cause a no crank/no start situation. Cleaning the key pellet and leaf contacts can frequently restore system operation. Because of the risk of contamination and other reasons, NO liquid lubricants should ever be used on the ignition lock cylinder. The generally accepted lubricant for ANY lock cylinder, whether a plate or pin type mechanism, is powdered graphite ONLY. This especially applies to VATS ignition lock cylinders.

    It is also common for the two wires from the ignition lock cylinder contacts to break due to the necessary flexing which occurs every time the ignition lock is moved. This can usually be diagnosed by measuring key pellet resistance at the VATS module or at the connector at the base of the steering column.

    There is a small two-wire connector in the upper bowl of the steering column which can become damaged or disconnected as well, since clearance between moving parts in the upper column bowl are minimal."
    Last edited by diamondstealth; 10-28-2009 at 02:24 PM.
    1997 GMC K1500 XC 9in 35's
    1990 GMC K1500 406, Predator Carb, 5Spd 32's

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    Re: 1998 K1500 Vortec 350 starts and dies

    My 98 doesn't have the pellet in the key, its just a normal key.
    08 HHR LS - 2.2 | 5 speed | 30 MPG

    98 K1500 Z71 - 204k | L31 | 60E | 3.73's | 3" BL | 33x12.5x15 Dick Cepek F-C II's | Dynomax Ultra Flo X DI/DO | 14 MPG

    84 S15 Jimmy 2dr 4x4 - engine/tranny all rebuilt

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    Re: 1998 K1500 Vortec 350 starts and dies

    I appreciate you, diamondstealth! We will see what is going on there.

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    Re: 1998 K1500 Vortec 350 starts and dies

    OK, his key is plain metal with no pellet. Any other ideas?

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    Re: 1998 K1500 Vortec 350 starts and dies

    What 98Greenmachine said. '98 doesn't use VATS, it uses a version of Passkey where the "chip" (resistor) is actually in the tumbler. It must correspond to the value that is contained in the TDM (theft deterrent module) which is integrated in the BCM (body control module.) Little black box under the dash next to the DRL diode. This is a new feature for '98 fullsize trucks.

    If in fact it is a Passkey problem the "security" light should be flashing or possibly lit solid on the dash cluster when it kills the engine. Is the bulb for the security indicator good (comes on during bulb check when you turn the key on?)

    Troubleshooting a Passkey problem can be frustrating; sometimes people give up and work around it. You can wire in a resistor of the proper value and that may work, some guys that install remote starts do this, but if the problem is downstream of the tumbler then the resistor probably won't fix it. You can also have the Passkey system tuned out of your PCM.

    Richard

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    Re: 1998 K1500 Vortec 350 starts and dies

    1998 to 2007 gmt400 & gmt800 trucks have passlock not VATs security Passlock has no chip in the key. You should have a security light coming on and this procedure needs to be done.
    - The EVO/Passlockô module
    - The passlockô sensor
    - The VCM/PCM



    The following is the Auto Learn Procedure:

    1) Insure the ignition key is in the ON position.

    2) Clear all EVO/passlockô module and VCM/PCM DTCs. Record and refer any VCM/PCM DTCs to:
    - For 5.0/5.7L engines, refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 5.0/5.7L

    3) Momentarily rotate the ignition key to the CRANK position (Do NOT start the vehicle), then release it to the RUN position (Do NOT key OFF in the process).

    4) Wait 10 minutes. Observe the SECURITY indicator. Refer to the following list for the appropriate responses:
    - If the passlockô sensor was replaced the SECURITY indicator will flash for the 10 minutes duration.
    - If the EVO/passlockô module was replaced, the SECURITY indicator will flash for a few seconds and then remain ON for the remainder of the 10 minutes duration.
    - If the VCM/PCM was replaced with a new programmed VCM/PCM and connected to the vehicle for the first time, the vehicle will start and this procedure may not be necessary.
    - If the replacement VCM/PCM was connected to any vehicle at any other time, even momentarily, the SECURITY indicator will flash for a few seconds and then remain ON for the 10 minutes duration.

    5) The SECURITY indicator will transition from flashing to ON briefly to OFF after 10 minutes if remaining in the ignition ON position.

    6) Turn the ignition switch to the OFF position and wait for 10 seconds.
    Repeat steps 3-6 two more times. The new security code is ready to be communicated among the Passlock sensor, EVO/Passlock module and VCM/PCM.

    7) The new password is learned on the next ignition lock cylinder cycle from OFF to CRANK to ON (start attempt).
    04 K1500 Silverado EXT 3:73 gears, 5.3L 265/75-16,Pace Edwards tonneau,

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    Re: 1998 K1500 Vortec 350 starts and dies

    I'll check it out. If I read redvet's post correctly, following that procedure should reset the security system. None of the security components have been replaced.

    Is there a wire coming from the tumbler as part of the system that could have a fault in it?

    We now have a new problem, apparently. Neighbor's spider seller guy showed up last night. Neighbor called me to say he now can only get 14 psi now out of the fuel pump when it initially runs. The truck has been sitting a few months, so who knows what has happened in that time. Looks like a new fuel pump is first before we can start on the other problems.

    I have not seen the wiring to the pump yet. If there are only two wires to it, like every other brand I have seen, we're screwed as far as maybe having a new pump solve all the problems. But if there are 3 or more, we have a chance that the pump is actually the culprit, even though it ran in the first portion of the start sequence. The pump was replaced a year before this problem cropped up. I doubt a new one will solve it all. Every other electric pump I have ever seen, when it fails, it is cooked. There is no partial operation.

    We are about to tow it from his house to mine and get it in my shop building. That means the SOB will HAVE TO RUN to get back out. If I have to, I will hotwire the pump to a switched circuit and leave it that way, if it will make the damn thing run. Unreal.

    Thanks for the help. Still open for any other suggestions. Oh yeah, lighting it on fire to collect the insurance has already been mentioned.

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    Re: 1998 K1500 Vortec 350 starts and dies

    You guys gave me the "key" when you typed "Passlock." Using that as a search, I have just gone through an exhaustive thread here:

    http://www.automotiveforums.com/t454520.html

    That, some other threads, some linked threads, have all led me to believe it may be as simple as leaving the key ON for 10-20-30 minutes, and resetting the code, as redvett describes.

    This would also explain why my neighbor says that when they put in the new fuel pump, it had a no-start condition like this, but that "it fixed itself." Could be that unknown to them, the key was left ON long enough for a new code to set.

    It is gonna be really funny if this truck has caused us all this grief for all these months, when all we had to do was let it sit ON for 10 minutes and fire it up.

    Once we do get it running, I am going to perform the toggle switch mod to it. I hope this finally works.

    I will report what happens and what we find.

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    Re: 1998 K1500 Vortec 350 starts and dies

    Hope it works for ya, its always nice getting new ideas to fix an old problem.
    08 HHR LS - 2.2 | 5 speed | 30 MPG

    98 K1500 Z71 - 204k | L31 | 60E | 3.73's | 3" BL | 33x12.5x15 Dick Cepek F-C II's | Dynomax Ultra Flo X DI/DO | 14 MPG

    84 S15 Jimmy 2dr 4x4 - engine/tranny all rebuilt

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    Re: 1998 K1500 Vortec 350 starts and dies

    Hey guys, we got the top of the tank exposed yesterday, so we can look right at the pump.

    I now have 2 quick questions:

    1.) There are 7 wires going to the pump, with two plugs. If I got the colors right: One plug has a gray, a brown with white stripe, and 2 blacks. The other has a gray, a green and a black. Anybody know where these go?

    I would like to be able to test them if possible to make sure they work correctly before putting in a new pump.

    2.) In trying to recode the passlock, the security light come son and stays on. It never goes out. We let it sit as long as 15 minutes, it did not go out. I ran through three 11-minute cycles as the relearn says, but the light never did go out. Wazzup with that?

    I sure was happy to see all those wires. The other makes I have worked on have 2 wires to the pump, so it either works or not. Having 7 means the pump could indeed be part-dead.

    Thanks!

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