OBS Ford question

Brownsxj

Well-Known Member
Joined
Mar 19, 2008
Location
Durham NC
Just bought a 89 F350 7.3, auto, 2wd.
When I go to hit the brakes driving, the RPMs start to drop till it cuts off. I can keep lightly tapping the gas pedal and it will keep running with the left foot as my brake. Quick search in google gives some testimonials that give some ideas, but let’s be real... it’s not nc4x4. Any input would be awesome.
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Brake booster leak? or a failed diaphragm if it even has one. sorry I may not be much help. Not much of a diesel or ford guy
 
How do those trucks work the brake booster? Do they have a vacuum pump? I can't imagine a situation where a vac pump would cause the engine to bog and stall, but you could easily pull the vac line off the booster while it's running and see what happens.
 
shawn said:
How do those trucks work the brake booster? Do they have a vacuum pump? I can't imagine a situation where a vac pump would cause the engine to bog and stall, but you could easily pull the vac line off the booster while it's running and see what happens.
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Bad Diaphram can cause it on gasoline engines. although I never heard it happening to a diesel because of the raw torque. I just threw a suggestion out there.
 
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