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1991 Buick Century INTERMITTENT (CRANKS BUT WILL NOT START)

Tiny
CCW
  • MEMBER
  • 1991 BUICK CENTURY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 21,400 MILES
EFI V6 3.3L:

1st symptom:
Starts cold, but after warm up, and turned off for 10-20 minutes cranks, but will not fire. Go cold and will start and run again.
2nd symptom: after warm up idles rough and stalls at redlight, studders when going downhill and throttle on idle position.
Otherwise, the old V6 has plenty of power, runs great.
Crankshaft sensor at the harmonic balancer has been replaced, fuel pump has been replaced. Ignition power transisitor module and new ECM did not clear the problem.
I suspect it may be some other sensors going out or sensor wiring going bad after the high mileage and weather exposure, such as throttle plate position, intake mass flow, etc. Which sensor(s) when intermittent and temp sensitive, will fool the ECM but not register a "service engine" fault?
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Tuesday, January 27th, 2009 AT 10:31 AM

3 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Hello, codes don't always set when they should.

Have you done any basic testing? Have a helper crank it, while you check for spark at the plugs and injector pulse. You probably should unplug all injectors or disable the fuel system, if your doing a lot of cranking. Let us know.
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Monday, January 14th, 2019 AT 9:45 AM
Tiny
CCW
  • MEMBER
  • 2 POSTS
Jdl123:

When in the fault mode (crank but no start), the injectors are getting pulse, no ignition ie. No spark.
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Monday, January 14th, 2019 AT 9:45 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I'd have to check the crank and sync signal from the crank sensor. With a dual crank sensor the wires are, ref voltage--ground--crank signal--sync signal. You can use a voltmeter to check those signal circuits with the engine cranking. Maybe a problem with the wiring circuit?
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Monday, January 14th, 2019 AT 9:45 AM

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