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Discuss 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS in the alt.autos.gm forum at Car Dealer Forums; I have a 1988 gmc truck 4.3 engine and about 2 weeks ago I pulled ...
  1. #1
    gsprinklerman
    Guest

    Default 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS

    I have a 1988 gmc truck 4.3 engine and about 2 weeks ago I pulled up to
    a stop sign and it quit running it was about half way warmed up, so I
    turned the key off and it restarted but it was running kind of
    weird.

    I noticed the voltage was kind of low so because the battery was
    kind of old I got a new one and installed that and did not have any
    more problems that day or evening and I started it many times.

    The next morning I went to start it and it would start and run for
    a few seconds and quit, so I had a can of starting fluid and had my
    son turn it over and when it tried to stall just gave it a
    tiny squirt of starting fluid and after it warmed up a bit it ran
    just fine.

    I kept having the starting problem so I took it to the local
    mechanic and he found the alternator was not producing enough
    voltage so he put on rebuilt.

    Voltage is now normal still had the starting problem.

    Then checked the fuel pressure and found that is as going below specs
    intermitently and so I had another valve body that he put on, that
    fixed the fuel problem at the time and it started good.

    Went to pick it up and it ran kind of funny and the next morning same
    problem.

    I drove it yesterday and was going down the freeway about 70 mph and it
    just quit but restarted again, and I am still having the starting
    problem.

    It takes about 5-6 times starting before it will run and if it sits
    longer than about 2-3 minutes
    it takes about 2 times to make it run.

    I have put on a new temperature sensor, and I tryed a used computer
    from a junk yard same problem.

    I had a new fuel pump put in about 70,000 miles ago. because of lack
    of power.

    Code readers do not show anything and the light does not come on.


    Can someone please help!!!!!!

    THANKS GARY


  2. #2
    edokamoto@netzero.net
    Guest

    Default Re: 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS

    If you have a vortec engine it has an octopus fuel delivery system. To
    make sure if you can see the injectors sitting in the throttle body it
    is not vortec, or you can see fuel injectors it is not vortec. If it
    is vortec then it has a fuel pressure regulator and injector hoses and
    poppet injectors inside the intake manifold under the upper manifold .
    Sometimes the fuel regulator starts to leak, take out the plugs and see
    if the plugs are fouled only on one side, it usually means the fuel
    regulator leaks into one side of manifold and whole regulator, injector
    assembly needs to be replaced, you can tell by removing valve on top of
    upper manifold and looking in with a flashlight, if one side is washed
    clean by gasoline then regulator leaks.



    gsprinklerman wrote:
    > I have a 1988 gmc truck 4.3 engine and about 2 weeks ago I pulled up to
    > a stop sign and it quit running it was about half way warmed up, so I
    > turned the key off and it restarted but it was running kind of
    > weird.
    >
    > I noticed the voltage was kind of low so because the battery was
    > kind of old I got a new one and installed that and did not have any
    > more problems that day or evening and I started it many times.
    >
    > The next morning I went to start it and it would start and run for
    > a few seconds and quit, so I had a can of starting fluid and had my
    > son turn it over and when it tried to stall just gave it a
    > tiny squirt of starting fluid and after it warmed up a bit it ran
    > just fine.
    >
    > I kept having the starting problem so I took it to the local
    > mechanic and he found the alternator was not producing enough
    > voltage so he put on rebuilt.
    >
    > Voltage is now normal still had the starting problem.
    >
    > Then checked the fuel pressure and found that is as going below specs
    > intermitently and so I had another valve body that he put on, that
    > fixed the fuel problem at the time and it started good.
    >
    > Went to pick it up and it ran kind of funny and the next morning same
    > problem.
    >
    > I drove it yesterday and was going down the freeway about 70 mph and it
    > just quit but restarted again, and I am still having the starting
    > problem.
    >
    > It takes about 5-6 times starting before it will run and if it sits
    > longer than about 2-3 minutes
    > it takes about 2 times to make it run.
    >
    > I have put on a new temperature sensor, and I tryed a used computer
    > from a junk yard same problem.
    >
    > I had a new fuel pump put in about 70,000 miles ago. because of lack
    > of power.
    >
    > Code readers do not show anything and the light does not come on.
    >
    >
    > Can someone please help!!!!!!
    >
    > THANKS GARY



  3. #3
    gsprinklerman
    Guest

    Default Re: 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS

    It is not a vortec just a TBI and it just stops completly no missing.
    I think it is the fuel pump that is involved some way or the wiring to
    the pump or the relay but I don't know how to check that myself.
    It will run if I squirt a little gas down the TBI so it keeps running
    then after about 2 minutes when it is cold it will run and then starts
    quicker when warmed up very strange,
    even if I just start it and it quits several times it will run without
    the spray of gas, so many starts I had to put in a rebuilt starter.
    I had a new fuel pump put in about 1 1/2 years ago.
    thanks for your feedback, do you have any other ideas?


    edokamoto@netzero.net wrote:
    > If you have a vortec engine it has an octopus fuel delivery system. To
    > make sure if you can see the injectors sitting in the throttle body it
    > is not vortec, or you can see fuel injectors it is not vortec. If it
    > is vortec then it has a fuel pressure regulator and injector hoses and
    > poppet injectors inside the intake manifold under the upper manifold .
    > Sometimes the fuel regulator starts to leak, take out the plugs and see
    > if the plugs are fouled only on one side, it usually means the fuel
    > regulator leaks into one side of manifold and whole regulator, injector
    > assembly needs to be replaced, you can tell by removing valve on top of
    > upper manifold and looking in with a flashlight, if one side is washed
    > clean by gasoline then regulator leaks.
    >
    >
    >
    > gsprinklerman wrote:
    > > I have a 1988 gmc truck 4.3 engine and about 2 weeks ago I pulled up to
    > > a stop sign and it quit running it was about half way warmed up, so I
    > > turned the key off and it restarted but it was running kind of
    > > weird.
    > >
    > > I noticed the voltage was kind of low so because the battery was
    > > kind of old I got a new one and installed that and did not have any
    > > more problems that day or evening and I started it many times.
    > >
    > > The next morning I went to start it and it would start and run for
    > > a few seconds and quit, so I had a can of starting fluid and had my
    > > son turn it over and when it tried to stall just gave it a
    > > tiny squirt of starting fluid and after it warmed up a bit it ran
    > > just fine.
    > >
    > > I kept having the starting problem so I took it to the local
    > > mechanic and he found the alternator was not producing enough
    > > voltage so he put on rebuilt.
    > >
    > > Voltage is now normal still had the starting problem.
    > >
    > > Then checked the fuel pressure and found that is as going below specs
    > > intermitently and so I had another valve body that he put on, that
    > > fixed the fuel problem at the time and it started good.
    > >
    > > Went to pick it up and it ran kind of funny and the next morning same
    > > problem.
    > >
    > > I drove it yesterday and was going down the freeway about 70 mph and it
    > > just quit but restarted again, and I am still having the starting
    > > problem.
    > >
    > > It takes about 5-6 times starting before it will run and if it sits
    > > longer than about 2-3 minutes
    > > it takes about 2 times to make it run.
    > >
    > > I have put on a new temperature sensor, and I tryed a used computer
    > > from a junk yard same problem.
    > >
    > > I had a new fuel pump put in about 70,000 miles ago. because of lack
    > > of power.
    > >
    > > Code readers do not show anything and the light does not come on.
    > >
    > >
    > > Can someone please help!!!!!!
    > >
    > > THANKS GARY



  4. #4
    Rixriv
    Guest

    Default Re: 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS

    I'll go one further with you. I have a 1988 GMC 5.7 engine. almost the
    same problem, but it is prevalent at idle. Running along is fine, but I
    notice the voltage gauge is right on the mark at 14 volts. Usually when
    running right it is the width of the needle about 14 volts.
    Here goes the problem. Often at an idle, the idle goes bad and I notice
    the voltmeter is now very low (12v approx) Racing the engine a bit the
    voltage comes back and the engine runs normal. I believe the lower voltage
    sends error signals to the TBI injection pulse via the computer. This
    racing the engine usually just comes back to 14, not a tiny bit higher.
    I tore into it the other night looking for corroded connections which
    could provide a voltage drop. To aggravate the condition, I disconnected
    the battery after starting and put my simpson 260 on the terminals.
    Noticed slighly more than 12 v. Putting on the headlights stalled the
    engine and when reconnecting the battery terminal and restarting I now
    have a definite low voltage. I am suspect of the alternator, but not
    certian. It is a rebuilt a couple years old, the battery is not quite a
    year old.
    Started it today after putting back all the cleaned cables and connections
    to the master terminal block no improvement. unplugged the field terminal
    to the alternator and it gave me the immediate low 12v indication. Be
    checking the master body connector and fuse connections now.
    Good luck Gary and any one else have any info?


  5. #5
    gsprinklerman
    Guest

    Default Re: 1988 GMC 4.3 1500 TRUCK STARTING RUNNING PROBLEMS

    The problems on my 1988 v6 4.3 turned out to be a very eratic fuel pump
    that was not very old but I acually got a warrantee on that, but not
    the labor of course.
    The other thing I might pass on is that a long time ago a used engine
    was installed by a local garage and they did not put the braces back on
    the alternator or the belt tensioner there are 3 braces on the
    alternator to the manifold and one on the belt tensioner to the
    manifold. I am thinking all the shaking was cause the alternators to
    fail early (replaced that twice) anyway the shaking finally broke the
    metal flange that holds these parts in place in front of the motor,
    replaced that and that is a job.

    Finally got 2 of the braces on the alternator from gm dealer but the
    long one on the alternator was discontinued and so was the one on the
    belt tensioner, been trying to get these from salvage yard, no luck
    yet.

    The other porblem was finding out the throttle shaft on the TBI was a
    little loose so I took a can of either with a extended tip and every
    time I spayed that right on the loose shaft the motor would pick up
    speed a little, so I found one that was tight and solved that
    problem, the vacumn leak would cause the motor to run very fast at
    Idle.

    Forgot to mention that the voltage was low on the alternator so that
    was changed along with the battery, but I think the shaking may have
    caused it to fail early.

    Don't know if this would help you solve your problems I am just a do it
    yourself guy.

    Good Luck

    Rixriv wrote:
    > I'll go one further with you. I have a 1988 GMC 5.7 engine. almost the
    > same problem, but it is prevalent at idle. Running along is fine, but I
    > notice the voltage gauge is right on the mark at 14 volts. Usually when
    > running right it is the width of the needle about 14 volts.
    > Here goes the problem. Often at an idle, the idle goes bad and I notice
    > the voltmeter is now very low (12v approx) Racing the engine a bit the
    > voltage comes back and the engine runs normal. I believe the lower voltage
    > sends error signals to the TBI injection pulse via the computer. This
    > racing the engine usually just comes back to 14, not a tiny bit higher.
    > I tore into it the other night looking for corroded connections which
    > could provide a voltage drop. To aggravate the condition, I disconnected
    > the battery after starting and put my simpson 260 on the terminals.
    > Noticed slighly more than 12 v. Putting on the headlights stalled the
    > engine and when reconnecting the battery terminal and restarting I now
    > have a definite low voltage. I am suspect of the alternator, but not
    > certian. It is a rebuilt a couple years old, the battery is not quite a
    > year old.
    > Started it today after putting back all the cleaned cables and connections
    > to the master terminal block no improvement. unplugged the field terminal
    > to the alternator and it gave me the immediate low 12v indication. Be
    > checking the master body connector and fuse connections now.
    > Good luck Gary and any one else have any info?



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