I have a 98 Ford ranger 4x2 just put all new brakes rotars drums calipers on and no braking g power co.e to find out #9 fuse which should be 7.5 keeps blowing any ideas why

 

Welcome to the forum

And what does fuse #9 power?

There are two fuse boxes, one in the engine bay and one in the cab, which fuse box is it?

You can get 1998 owners manual here: https://www.ranger-forums.com/genera...1-models-3747/
It shows what fuses power what devices

There are no electrics involved in braking, so "No braking power" will be a hydraulic or mechanical issue.
Did you bleed the brakes after the replacing parts?

ABS(anti-lock brake system) does use electricity but can't cause weak braking
So blown fuse is not the cause of "weak brakes"


Fuse #9 in the cab fuse box runs to the brake switch but not brake lights, the brake switch has 2 switches in one box.
Fuse #9 12volts runs thru one side of the brake switch and goes to ABS, Cruise Control and computer
Fuse #13 20amp, 12volts runs thru other side of brake switch to the 3 Brake lights

So could be bad brake light switch or shorted wire to ABS or cruise

 

As soon as u put the fuse in and barely tap the brakes it blows the fuse

 

Check the switch first, with OHM meter
Unplug wires and test each switch contact to see if its Grounded, then test each wire
The switch has two separate switches inside, one for brake lights, using different fuse, and one switch just for fuse #9
So it should have 4 or 5 contacts, NONE should be grounds

Brown wire is from Fuse #9 so it is OK or fuse would blow as soon as you put new fuse in
The Red/light green stripe wire goes to ABS, Cruise and computer<<< this is the wire that may have a short to ground, under 5 OHMs is a short