95 Mercury sable

1995 MERCURY SABLE
89,000 MILES • 6 CYL • 2WD • AUTOMATIC
Avatar
PHOTOGCEO
  • MEMBER
  • 6 POSTS
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?
Mar 17, 2011 at 1:36 AM
Advertisement
Avatar
CARADIODOC
  • CAR REPAIR CONTRIBUTOR
  • 34,309 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.
Mar 17, 2011 at 1:42 AM
Avatar
PHOTOGCEO
  • MEMBER
  • 6 POSTS
ok, well the batter is about.....12 hours old. i bought it yesterday and since then have driven the car around 45 miles.
Mar 17, 2011 at 1:45 AM
Avatar
CARADIODOC
  • CAR REPAIR CONTRIBUTOR
  • 34,309 POSTS
Did this problem start before you replaced the battery? Was the old one defective or just run down?
Mar 17, 2011 at 2:00 AM
Avatar
PHOTOGCEO
  • MEMBER
  • 6 POSTS
It started after, the battery was run down.
Mar 17, 2011 at 2:10 AM
Avatar
CARADIODOC
  • CAR REPAIR CONTRIBUTOR
  • 34,309 POSTS
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.
Mar 17, 2011 at 2:22 AM
Avatar
PHOTOGCEO
  • MEMBER
  • 6 POSTS
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.
Mar 17, 2011 at 2:42 AM
Avatar
CARADIODOC
  • CAR REPAIR CONTRIBUTOR
  • 34,309 POSTS
I figured that was the case. At 6000 rpm there would be pistons going through the hood and NASA would be tracking them!
Mar 17, 2011 at 2:50 AM
Avatar
PHOTOGCEO
  • MEMBER
  • 6 POSTS
hahaha okay, thankyou for your help i'll check on it in the daylight.
Mar 17, 2011 at 2:53 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.