Brake pedal-Stopping ability?

[Blanco]

I'm on my Holiday off roading trip & tonight on my way back from a full day of wheeling I noticed that if I pump my brakes a few times, The pedal get very hard to push on ( Like non-power brakes ) & my Brakes light lights up on my dash?

I still have at least 1000 miles left on my Off Roading holiday with at least 3 more days of wheeling..
& I wonder what might this issue be?
Do I need to worry about it?
Should I fix ASAP?

Is this common?
If so what wrong & how do i correct it?

Your help is greatly appreciated...

[K5Cruiser]

Sounds like an issue with the master cylinder possibly. Do you feel any change in the brakes ability to stop the vehicle?

[fordmedic]

My first thought is vacuum pump.

[Blanco]

Sounds like an issue with the master cylinder possibly. Do you feel any change in the brakes ability to stop the vehicle?

Yes!
After pumping the brakes a few time in a non-normal way, the pedal get very hard to push, & if I had a panic stop I would have to stand on it hard!
But it will stop.

I learned this while pumping the brakes to make the rig dance to a song that was on the radio.

My first thought is vacuum pump.

Thats sorta what I was thinking too.
Being it feels like all the power in the power brakes leaves the system.

[SandShark]

the ambulances at my work would do the same thing. i dunno if u can on your truck but when i did it in the ambulance the vacuum pump would start working and i could hear it. when it would stop making noise. all would be back to normal. so maybe your just draining the system of all its pressure and it takes a bit to catch. up. also its recommended not to pump the brakes like that i don't think. and that could be why. risk of having a hard time stopping and or wearing the pump out faster. who knows.

just my .02 cents worth. could be wrong.

[Blanco]

Trust me, now that I've learned this..... I wont be goofing around like that & saving the power brakes for when its needed. :o

I'll keep an eye on it to see if it gets worse..

[Ftreefitty]

ok I've been thru my fair share of vacuum pumps. It will stop without it standing on it on level ground with enough room but SCARY. i put in an engine braking system so I feel better anyway so stay safe and keep your eyes and ears on it. maybe even a vac. gage. I fixed mine out on the road by getting one of those cheapy little 12 v air compressors. put it on the left fender well where the air box used t'be and plumbed the suction side to the vac manifold using the stock vac. hose. and connected the big alligator clips to the battery. I even thought about putting it in there more permanent on an emergency bake switch and a T

[Blanco]

That sounds interesting..
Now that I've started towing my boat around regularly I'm thinking about the brakes again especially because the boat trailer has no brakes. ( its a light boat )