Question about 1991 Buick Century

1 Answer

Won't start after a short trip until cooled off

I have changed the following parts with new ones:
spark plugs
spark plug wires
ingnition module
coil packs
fuel pressure regulator
crankshaft position sensor
TPS sensor
fuel filter

I have tested the following and fould them operating correctly:
ECT sensor
park/neutral switch
EPROM chip in computer
water pump
all lights in the dash
fuel pump

As this vehicle is not equiped with an EGR system of any kind it is unusual to diagnose. I also installed a boost gauge to monitor for vacuum leaks and it appears to lose vacuum after it is fully warmed up and you press the gas, even slightly. It loses horsepower at this point, and will eventually die if left in park or neutral for any long length of time. It takes a long time to take off from a red light for the lack of power. If I floor it from a stop the engine will miss and sputter and sometimes dies. It seems to be an ignition problem, but I can't seem to find it. The only 2 sensors I haven't replaced yet are the camshaft sensor and the knock sensor, as I can't seem to locate them without taking the engine apart. Chilton's and Haynes have no information as to where these sensors are located. The engine after fully warmed up operates at -20 vacuum at idle and is almost zero if you press the gas pedal slightly.

canister purge valve solenoid? I am at a loss...

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  • Mike Jul 24, 2009

    If the catalytic converter was stopped up it wouldn't run right, EVER.

  • Mike Aug 06, 2009

    Where are you getting your information from? The catalyst doesn't swell with heat!?! How in the world could it get worse with heat? The honeycomb design is so if there is a significant blockage, the exhaust pressure will either: A-blow out a flange or manifold gasket, or B-blow out part of the fragile honeycomb catalyst. Another thing, no one with any sense would suggest taking out the O2 sensor for any reason other than to replace it. Especially on a DIY network like this. You should know that it is reckless to tell someone to take out the O2 sensor without telling them that it is important to do it while the exhaust is hot otherwise chance breaking the sensor or ruining the threads..."Nostradamus" i am not, but maybe a touch more "in the know" than you. I am looking for an EXPERT on GM V6s, and I get clowned on by a 12 year old...

  • Mike Sep 15, 2009

    I took the car to A-1 Auto Electric, and they found that the voltage regulator wasn't working consistently when hot. They also found that one of the brushes on the alternator was worn out and didn't make good connection when hot. This is after I had the alternator and voltage regulator checked at 2 different places with machines. I guess the best thing to do in a tough situation like this, just take it to an expert. I got my car back the same day and the diagnosis was free. The engine stalled and won't restart due to irregular voltages comming to the IAC valve. Thanks for trying Honeymokey...



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Sounds like the converter is stopped up.

Posted on Jul 03, 2009

  • honeymokey
    honeymokey Jul 25, 2009

    Wrong Nostradamus! It may be partially stopped and when it gets hot it will get worse. Remove the o2 sensor and run car then test vacuum.

  • honeymokey
    honeymokey Aug 07, 2009

    Like I Told you. You already know everything and nobody can tell you anything. It's obvious that you have a closed mind and know absolutely nothing about automotive mechanics. You failed to read that I said to test it, with the o2 out. It looks as if you have never passed any test in your life anyway, so keep you moronic dunce hat on that you wear so well. In touch with reality you are not, you are wasting money by guessing and throwing parts at it. By your post you seem to be less than twelve years old and starting to have a tantrum, because of your failed attempts to fix this simple problem.



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