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1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

New guy with problems

Old Oct 26, 2004 | 01:23 AM
  #1  
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richierich39
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New guy with problems


I just bought a 1985 Flareside w/302 FI w/air ,auto and 4x4 .This truck has been sitting for a year and has 80,000 miles on it. I have been driving it for a couple of days now and have noticed a few things I hope ya'll can help me figure out.
First of all the tranny seems to be shifting real hard. And it seems to be idling rough. ( i did a complete tune up last week) And today while sitting at an idle I noticed the brake pedal starts to slowly go to the floor. After idleing for awhile at a light, the brakes were gone. When I took off and hit the brakes again they worked. Do you think my booster is going bad or could it all be do to a vacuum leak some where. I have been trying to chase down all the vacuum lines and can not find any off or bad ones. If any one has a diagram for a 85 can you lead me to it? Any ideas where to start looking ?

Thanks in advance,
Rich
 
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Old Oct 26, 2004 | 02:19 AM
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big hoss 29
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From: Billings Montana
As far as your rough idle and hard shifting, check your Throttle Position Sensor. It controls your idle and the tranny shift points. If you check your codes, you might come up with some answers.
Listen for a hiss coming from around the booster if you think it's a vacuum leak.
 
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Old Oct 26, 2004 | 10:40 AM
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I would think that the master cylinder is going bad.
Consider the going down at a redlight as a warning and fix it before you hit something.
 
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Old Oct 26, 2004 | 01:36 PM
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RR4E
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I would check the booster as well. You won't always hear a hiss when they've gone bad, but they will also cause the pedal to slowly fall to the floor when at a red light. Happened to my '69 F100, and replacing it cured the problem. I would also check for brake line, wheel cylinder, and caliper leaks as well. Pay particularly close attention to your flex lines(rubber brake lines near the front wheels, and roughly center of the diff, in the rear) for cracks and possible leaks. I'd consider running some injection/carb cleaner through the tank with your next fill as well. May even want to do so for the next few tank fulls. A truck that has sat for a while will be gummed up on the inside, and you may find this alone really cures the rough idle problem.
 
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Old Nov 2, 2004 | 11:51 PM
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From: Crosby TX
It's your Master Cylinder bypassing between the front and rear chambers.

I just had the same problem and replacing the Master Cylinder fixed it all.
 
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Old Nov 3, 2004 | 10:00 AM
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richierich39
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Thanks guys
I replaced the booster and master cylinder and put some injector cleaner in and now its running and stopping great!

Thanks for your help, Rich
 
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