So this fire issue with the cruise switch mounted on the master cylinder is not an issue with this model year? That would explain why my MC looks completely different than everyone else. (no forward mounted sensor on top)

I'm going to try to find these plugs and do some more troubleshooting. Stay tuned...

 

The fire issue that triggered the recall for many Ford vehicles in this vintage does not apply to your 1992 model year F-series truck. The problematic Brake Pressure switch does not exist.

 

That's the first bit of good news I've gotten since I started this project. Thanks for all the great info rla2005!

 

[QUOTE=rla2005;18091550]I have always found if the brake pedal stays firm and no dropping with the engine off the problem is vacuum based. If the pedal does drop and/or softens up the problem is hydraulic. If you can find plugs for the master cylinder ports you could remove the lines, plug the ports then see if the pedal drops. If it does, the master cylinder is bad. If not, the problem is further down stream.[/QUOT




Not to hijack the thread but Randy, my 91 pedal is mushy and I just did the pedal and it stays firm with engine off. Where would I check for the vacuum issue? Thanks Sandy

 

OK. I put in the block-offs for the MC and with the engine off, the pedal was hard as a rock. Wouldn't even budge. I'm assuming then that means the issue is somewhere further down the line?

 

My experience has been a bad vacuum booster causing the soft pedal with the engine running.

 

Try that same test with the engine running. If it's still rock hard, the problem is downstream.

 

This is what I experienced also.