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Oct 29, 2006 | 09:41 AM

1poorboy69

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help no brakes

hey guys i have a 97 250 and when the truck is fisrt started the brake light is on and i have no brakes and a very hard pedal. problem fixes itself in a minute after truck is running. i have tried pulling the booster hose off and still have plenty of vacum on the booster, even after it has set all night. any other ideas??

Oct 29, 2006 | 10:12 AM

rockyrider

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More of the same.

https://www.ford-trucks.com/forums/5...ntermiten.html

Oct 29, 2006 | 10:20 AM

79f-250custom

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From: Wisconsin

Maybe it just takes a few seconds for your pump to make vacuum?
Mitch

Oct 29, 2006 | 10:37 AM

Cuda_jim

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From: MICHIGAN

Quote:

Originally Posted by 1poorboy69

i have tried pulling the booster hose off and still have plenty of vacum on the booster, even after it has set all night. any other ideas??

Did you measure the vacuum in the booster or just hear the hissing of air going into the booster? The amount of vacuum remaining in the booster should be the same as the amount it had when you shut it down the night before. IF not, It takes a few seconds for the vacuum pump to replentish the booster with enough vacuum to make the pedal feel normal. The booster can have leaks in a couple places but it is ususally not seviceable, it just needs to be replaced however, the check valve is replaceable. I personally have seen both go bad. My .02 cents.

Last edited by Cuda_jim; Oct 29, 2006 at 10:43 AM.

Oct 29, 2006 | 01:57 PM

SavageVertigo

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Joined: Sep 2006

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From: Maple Ridge, BC

Mine was doing the same thing for about 6 months or so till one morning this fall no power brakes till i drove for a bit. turned out ot be the vac pump, only had 8 inches of vac at idle. new vac pump is almost 25 inches at idle now

just an idea, check to see what u have for vac at the pump when u first start it up it should climb up fast if the pump is in good shape

Oct 29, 2006 | 05:30 PM

tjbeggs

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From: Silver Lake Dunes, MI

best thing to do is the measure vacum with a gauge first then go from there. the spec at idle is 18 in. hg anything less than that right off the pump and you need a new pump. its important to measure that at the line coming right off the pump that will rule out any leak making the pump look bad. if the pump is good you have a leak somewhere. You can get a hand vacum pump from a parts store then pump down the heater control system and various other systems that use vacum to find which on is leaking then by process of elimination find your leak.