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95 Mercury Sable

Tiny
PHOTOGCEO
  • MEMBER
  • 1995 MERCURY SABLE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 89,000 MILES
I have a 95 mercury sable, when I turn the key it turns over very slowly. Once it fires up the rpms from 1000 to 4000 randomly. One I drive it goes form 1000 to 6000 randomly. What could it be?
Thursday, March 17th, 2011 AT 1:36 AM

8 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,871 POSTS
Start with testing the generator. Use an inexpensive digital voltmeter to measure the battery voltage. If you find around 11 volts or less, suspect a bad battery. If it is closer to 12.0 volts or higher, remeasure it with the engine running. It must be between 13.75 and 14.75 volts. If it stays around 12 volts or less, we have to diagnose the generator and voltage regulator.
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Thursday, March 17th, 2011 AT 1:42 AM
Tiny
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Ok, well the batter is about.12 hours old. I bought it yesterday and since then have driven the car around 45 miles.
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Thursday, March 17th, 2011 AT 1:45 AM
Tiny
CARADIODOC
  • MECHANIC
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Did this problem start before you replaced the battery? Was the old one defective or just run down?
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Thursday, March 17th, 2011 AT 2:00 AM
Tiny
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It started after, the battery was run down.
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Thursday, March 17th, 2011 AT 2:10 AM
Tiny
CARADIODOC
  • MECHANIC
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Yup, start with measuring battery voltage with the engine running. If it is low, like near 12.0 volts, we'll be heading to the generator next. Measure the voltage on the fat output wire bolted to the back and on the smaller ones that plug in on the side.
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Thursday, March 17th, 2011 AT 2:22 AM
Tiny
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Okay, one thing I forgot to mention was even though the tach is reading that it is going between 1000 and 6000 rpm, the engine doesnt seem to actually be reving to that rpm. It seem to be at normal idle.
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Thursday, March 17th, 2011 AT 2:42 AM
Tiny
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I figured that was the case. At 6000 rpm there would be pistons going through the hood and NASA would be tracking them!
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Thursday, March 17th, 2011 AT 2:50 AM
Tiny
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Hahaha okay, thankyou for your help i'll check on it in the daylight.
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Thursday, March 17th, 2011 AT 2:53 AM

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