1991 Ford F350 power brakes not working

1991 FORD F-350
120,000 MILES • V8 • 4WD • MANUAL
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TOM BEESLEY
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  • 1 POST
My truck’s power brakes has stopped working actually I have not had power brakes for 2 years. I should also add that it is a crewcab diesel (7.3L Navistar IDI). My hydraulics appears to be fine with no leaks nor does the fluid reservoir ever drop.
Do you have any suggestions for diagnosing the problem?

Thank You for your help and time in this matter
Tom
Jan 4, 2008 at 3:47 PM
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MERLIN2021
  • ✓ASE Certified Mechanic
  • 17,250 POSTS
  • ASE Certified Mechanic
First thing I need to know is is this a Super duty? Have rear drum or disc brakes? antilock light on or off? Red brake light on or off? Tranny mounted parking brake? or Drums? Have you checked the belt to the vacuum pump? Does the pump produce vacuum? Disconnect the vac line at the booster, any air rush out?
Jan 4, 2008 at 3:52 PM
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MERLIN2021
  • ✓ASE Certified Mechanic
  • 17,250 POSTS
  • ASE Certified Mechanic
Disconnect the vac hose at the booster, take a vac reading therer, you should have 15-19hg....if not the vac pump, or vac switch on the fender is NG! If you only get 4 hg, at the pump, it should be replaced...
This answers your PM to me!
Jan 5, 2008 at 5:17 PM
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