FUEL PRESSURE IS 45PSI, PUT NEW CRANK POSITON SENSOR (THINKING THE THERMAL RUN AWAY PROBLEM), NO CODES, ONLY THING CAN SEE IS THE MAP SENSOR HG RAISES JUST BEFORE THE STUMBLE THEN GOES BACK TO 9HG RUNS GOOD UNTIL STUMBLE AGAIN, NEW FUEL FILTER , AIR FILTER ,AIC VALVE NEW , CLEANED MAF AND PORT , BEFORE AIC AND CLEANING RAN REAL RUFF NOW WILL AS I CALL IT HICK UP ABOUT ONCE EVERY MINUTE IN THE 195 DEGREE RANGE NOT SO OFTEN WHEN WEATHER IS COLDER PROBLEM CAME ON WITH NO CAUSE CAR HAS 200,000 REGULAR OIL CHANGE AND FLUIDS WAS GOING TO CHECK PCV AND MAP SENSOR NEXT ANY CLUES TO PROBLEM NO SMOKE NO LEAKS ALSO NOTICED A LACK O F PEDAL RESPOSNSE SINCE THIS STARTED
I would suspect the MAF sensor is defective. It is one part that will not set a fault code when it goes bad.
SOURCE: buick lesabre nightmare
Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.
SOURCE: 92 Buick Le Sabre engine stumbling/hesitation
Have you checked fuel pressure? How about spark on all 6 cylinders? Maybe a coil?
SOURCE: 1990 Buick Regal 3.1 has rough idle, hesitates and dies when accelerating.
A lot of new parts! Have a compression test done to gauge the engine's internal condition, and go from there. If compression is good on all 6 cylinders, scan for trouble codes. The compression test may find your problem, something like an exhaust valve burned or not seating properly.
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