1993 Mercury Sable stalls

Tiny
DEAN123654
  • MEMBER
  • 1993 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 75,000 MILES
It seems that when I have been in stop and go traffic and it is hot, not overheating, just hot outside and been running a while, 1hr-1.5hr. It stalls. It seems like it is loaded up, or the old vaperlock feel from the cars in the 70's. When I try to start it, it will not start and will not ideal. After about 20 minutes it will start and then seems to shift weird.

Can you help? I have cleaned the injectors, fuel fillter and tune-up. What can it be. Some people say it is the computer.
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Wednesday, November 11th, 2009 AT 2:49 PM

5 Replies

Tiny
MATHIASO
  • MEMBER
Temperature-related intermittents often mean a circuit is shorting out or opening up as a result of thermal expansion or contraction. Heat may be causing a loose or corroded connector or ground to break contact. Microscopic hairline cracks in circuit boards, soldered connections, wiring connectors and even integrated circuits may open up as operating temperatures rise. An injector solenoid or ignition coil that shows normal resistance at room temperature may short out or open up when it gets hot. The same goes for relay coils and contacts. Sometimes diodes and transistors can become flaky at high temperatures and/or voltage loads, too.

Temperature effects on electronic components can be simulated with a blow comb or hot air gun. By directing heat at suspicious connections, modules or other components, you can sometimes get the part to misbehave when it gets hot. If so, this would confirm the problem and complete your diagnosis. The next step would be to replace the faulty component.

Changes in operating temperature also affect the way the PCM controls spark timing, the fuel mixture and other emissions functions. If an intermittent problem only occurs after the vehicle has been driven several miles, it may be occurring when the PCM goes into closed loop. The underlying cause might be a bad oxygen sensor signal, airflow sensor signal or MAP sensor signal that is upsetting the air/fuel mixture.

If a problem seems to occur only when the engine is running in closed loop, that would tell you it's probably a sensor or PCM-related issue. The strategy here would be to look at some of the key sensor inputs with your scan tool to see if readings are within normal limits. Some problems may occur too quickly for the normal data stream to detect a fault, so you may have to hook up a digital storage oscilloscope to detect a momentary glitch.

Temperature also can cause mechanical things to stick as a result of thermal expansion when a part gets hot. Valves and lifters can stick if an engine overheats. EGR valves can stick from heat or a buildup of accumulated carbon deposits. Relay contacts may be affected by changes in temperature, too.

One thing to check here is the operation of the cooling system. A low coolant level may prevent the thermostat from opening and closing normally. An inoperative electric fan or a clogged radiator also may allow unwanted fluctuations in engine temperature that affect the way it runs.
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Thursday, November 12th, 2009 AT 7:23 AM
Tiny
DEAN123654
  • MEMBER
Yes, everything that you said is correct. What I was hoping for was an expert opion of what is the most common issue. I am sure that my car isn't the first one to do this, and with all the resources that this web site has I would think that you guys could narrow it down some. Thanks for all your efforts, but this really didn't help me.

Updated 11/17/09
No problem, I think that you might be on to something the other day I did hear a buzzing under the car. Now it didn't stall, but I had not heard this buzzing sound before. Do you think it might be the catlitic convertor? Maybe when it gets hot and the carbon build up expands it chocks out the exhust.
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Monday, November 16th, 2009 AT 5:25 PM
Tiny
MATHIASO
  • MEMBER
Are you giving up on me :-)
when the car do not start, open the fuel filer neck and listen to the fuel pump' look for strong buzing sound when a helper is try to start the car.
You may have a weak fuel pump.
Try that and let me lnow, we 'll check one thing at the time.
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Tuesday, November 17th, 2009 AT 1:46 AM
Tiny
JDL
  • EXPERT
Hi, I agree with Methiaso, I have seen people say, will the problem is usually this or that. So they end up throwing parts at it. When it doesn't fix anything, then they start doing tests that should have been done in the first. I agree, when the problem occurs, do the testing first before replacing anything. Just my thoughts, didn't mean to but in.
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Tuesday, November 17th, 2009 AT 12:20 PM
Tiny
2CARPROS MIKE
  • ADMIN
We are here to help and appreciate your donation. We do our best to provide solid advice. Our tech will continue to work with you to diagnose your problem. If we can't help you we will refund your donation.
Thanks,
Mike
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Tuesday, November 17th, 2009 AT 1:07 PM

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