Need help with '89 Buick Century 2.5

Discussion in 'Shop Talk' started by clovis, Dec 7, 2005.

  1. clovis

    clovis Well-Known Member

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    Hope you all can give me some insight on my car problem.

    I have an '89 Buick Century with 2.5 four cylinder. 100K miles on it.
    It has been a great car since I bought it in '95.

    In the past year, the car has been dying under these conditions:
    1) After driving for some time, like a 60 mile trip @70mph, letting up on the accelerator when getting off the interstate,
    2) Seems to happen when it is below 50 degrees outside.
    3) Problem seems to be getting progressively worse....today it died when driving in town, something that has never happened before.

    After the car dies, it is difficult to restart, unless I pour gas or ether in the thottle body. Seems to always run fine after that. Without pouring gas into the throttle body, sometimes it will eventually restart, but then will die again within a mile of driving.

    Car starts with ease at normal conditions, almost always on the first try.

    I have new plugs in the car, and have plenty of great blue spark.

    Any thoughts or suggestions????

    Thanks in advance!!!!!
    clove
     
  2. clovis

    clovis Well-Known Member

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    I also need to mention that at one time, the car would "stumble", and often die, after I started it when the motor was cold, no matter what the temperature was outside.
    That problem has seemed to go away some time ago, and now I have the above problem.
    Again,
    Thank YOU!!!!!!
    clove
     

  3. agmantoo

    agmantoo agmantoo Supporter

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    If you have not changed the fuel filter that needs to be done first. If the problem persists the fuel pressure needs to be verified. A failing fuel pump will give similar symptoms.
     
  4. clovis

    clovis Well-Known Member

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    Fuel filter was changed about two months ago. Still has the same symptoms.

    How do I check the fuel pressure....does the car need to NOT running to figure this out?
    Thanks!
    clove
     
  5. agmantoo

    agmantoo agmantoo Supporter

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    The pressure will be tested at the engine compartment by accessing the fuel delivery line. The fuel pump is in the tank and there is a filter screen on the intake to the pump. This screen is subject to clogging. The fuel pressure test will determine if the delivery pressure is adequate. The test can be made with the car in running condition. The engine does not have to be in failure mode to test.
     
  6. clovis

    clovis Well-Known Member

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    Ok. Cool.

    Any chance that the testing equipment is affordable?

    Have two shops in town that can do this test. One is a GM dealer, and the other works HARD at being dishonest to cheat people to line his own pockets.

    Do you think this could be a throttle sensor unit that has gone bad?

    Also, the car does not have any other signs of this being a bad fuel pump....it starts super easy normally.

    I am here to learn, and greatly appreciate your help.
    clove
     
  7. agmantoo

    agmantoo agmantoo Supporter

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    clovis, to specifically ID the exact cause without test equipment would require a crystal ball. I do not think it is the throttle position sensor. I am starting with what I think is the highest probability and eliminating as we go. Lets see if Beeman will respond as he is very knowledgeable. You can rig a pressure gauge once you see how your particular vehicle is plumbed. Some have a schraeder valve and others you have to tee into the line. You need to do some research to determine what the required pressure is for your specific engine. The fuel pump is expensive and the fuel tank has to be dropped to access the pump. Have you called one of the discount auto parts stores to see if they can loan a gauge or read your pressure? Ask what a cheap pressure gauge sells for when you have them on the line.
     
  8. Hip_Shot_Hanna

    Hip_Shot_Hanna Well-Known Member

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    I had a GM that froze up the Carb in Cold weather , there was a diverter on the air filter that turned the air intake to pulling tha air from around the exhaust manifold , the valve quit so it sucked air from behind the grille and it froze the carb in cold weather ,
     
  9. Beeman

    Beeman Well-Known Member

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    I read the original post but as others said it will take a little more diagnosis to get in the ballpark. Let's start with some questions.
    First question is does the Check engine light come on When you turn the key on with the engine off? If it does this is normal and we can go from there. With the engine running does the light come on or stay on? It doesn't matter which, but it will help to diagnose. If the light comes on while running you will need to have the codes retrieved, Auto Zone and Advance will do this for you for free.
    Has any recent work been performed on the car? Your guess about a throttle position sensor might be on the money but without diagnosis it's just a guess. A common problem on that engine is during valve cover gasket replacement a shield is left off of the EGR valve allowing heat to melt the throttle position sensor and or wires causing problems.
    Fuel pressure check on that car is a bit of a PIA. They did not put a shraeder valve tap on throttle body injected cars so tapping into the line is harder. We use an adapter that replaces the fuel filter which allows a pressure hookup. The fuel filter is under the hood on that car if I remember correctly. Throttle body injection doesn't require very much pressure like port injection so you don't see as many low fuel pressure problems on TBI cars, usually total fuel pump failure.
     
  10. clovis

    clovis Well-Known Member

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    Thank you for replying.

    I have a new set of problems, which I will mention later.

    The service engine soon light has never come on while having this problem (when the car is running and then dies).

    The service engine soon light does come on when starting, but it does not flash in the on position. This light goes out when it should.

    I replaced the fuel filter on the car a couple of months ago, and didn't cure the problem. I could blow easily thru the old one, if that means any thing. (This was under the car.)

    I have also tried Gumout fuel additive and a host of similar products, which did not help.

    I did have the valve cover replaced about 5 years ago by a super meticulous mechanic, and I helped. I know that we did not remove a heat shield....there were no parts left over. It was replaced about 8 years ago also, I wonder if it was left off then?

    Now, as much as I hate to admit it, my new problem that I will have to also work thru: In desperation, I poured gas into the throttle body to get it going.
    The car backfired, and started a fire. I burned the air filter and an electronic gizmo on the side of the throttle body. I will have to replace it, but the car started and I drove it. Please remember that I was foolish, but desperate.

    The car does run rough now, with the service engine soon light on.

    Again, thanks. I really do appreciate your help!
    clove
     
  11. clovis

    clovis Well-Known Member

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    Also, the car has never been hard to start. Always fires on the first try, even now.
    If the car stalls and dies, it is really hard to restart, but only then.
    clove
     
  12. Beeman

    Beeman Well-Known Member

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    To remove the valve cover the EGR valve must be removed. This is the big round thing at the back of the valve cover bolted to the intake. It has a vacum hose going to it. It is held on by 2 bolts and one bolt holds a tin heat shield which protects the throttle position sensor.
    I'm not sure what you're saying about the check engine light. It doesn't matter if it comes on when you have the problem, did or does it come on at all? The reason I asked about if it comes on with the key in the on position is many cars that old have been worked on and I have seen bulbs removed or covered over to hide the light instead of fixing the problem.
    The electrical part on top of the throttle body is the injector itself. The electrical part on the side with 4 wires is the idle air control valve. The electrical part in the rear with 3 wires is the throttle position sensor.
     
  13. Beeman

    Beeman Well-Known Member

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    After re reading your first post I notice you related the problem to temperature. You might have a temp sensor which is out of range. If the temp sensor reads a false hot temp when it's actually cold it will not allow enough fuel.
    With all that has gone on try this.
    Remove the battery cable and wait a minute, this will clear all stored codes from the memory. Reconnect the battery and start the car and drive it until the light comes on. Have the codes retrieved and see what you get.
     
  14. countrymech

    countrymech Well-Known Member

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    Clovis I have been reading your posts about the Buick and was wondering if you have checked the trouble codes yet? Usually anything that kills the engine will leave a code. That code might not be the direct cause as much as a symptom, but it will limit your search somewhat. If you don't own a scan tool (highly recommended for any vehicle owner) you can obtain these codes by jumpering a wire across the A & B terminals on the test terminal under the dash. I assume that you own a Chilton's or other manual for this vehicle as it will probably contai the code lists and a basic explanaition for it. If you can determine which parts of the system are picking up the problem then you will need the appropriate test gear to isolate the cause. You have been given alot of good advice so far but I just wanted to add a couple of other options to look at. The TBI system has a fuel pressure regulator that regulates the fuel pressure and also allows spillback of extra fuel back to the tank. If this sticks or fails it will cause the problem you describe. Also, does this problem happen under a load, does the engine seem to bog if you run the AC or go uphill? This could indicate that your EGR valve or solenoid has a problem and this problem will usually only occur only after the engine has reached operating Temp and the ECM is controlling the fuel according to exhaust values and the o2 sensor. The tools needed to diagnose this problem can be pretty pricey but can pay for themselves many times over, especially if you own multiple vehicles or have friends and family that are not mechanically inclined. With that said, it may be better to take it to a shop and have them scan it. For a small fee they will put a tester on the vehicle and then tell you what they found allowing you to fix it yourself. You can spend an awful sum of money replacing parts on a hunch. Best of luck.
     
  15. clovis

    clovis Well-Known Member

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    Guys,
    Thank you again for all your help.

    Since I caught the car on fire, which partially burned the idle air control valve and the four wires.

    Where does the wiring harness with the four wires go? One end hooks to the IAC valve....where is the other?

    Hard to remove from a junk car at the junk yard?

    BTW, what would you expect to pay for this harness, you remove, from the junk yard?
    What about the throttle body injector?
    Thanks!
    Clove
     
  16. cfabe

    cfabe Well-Known Member

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    The harness with the IAC connector is the entire engine harness that goes back to the ECM in the passengar compartment and it will be a royal pain to replace the whole thing. You'll be much better off cutting off the connector you need and splicing it into your harness. Use solder and heatshrink to splice.