Little to no brake pressure?

[Haficon]

So for no good reason my 86 MJ seems to have lost its brakes. If you pump rapidly on the pedal they come back for a minute but fade out quickly, the engine does loose RPM while you are holding/pumping the pedal. Makes me think something might have failed in the brake booster causing a vacuum leak once you apply the brakes. Fluid level is good same as it has been no leaks in the system. Truck sat for a year or so before I bought it, changed the front calipers and pads, bled it and drove it home at that time the brakes were normal.

 

Ideas anyone?

 

 

Thanks,

James

[HOrnbrod]

Good brake troubleshooting guide HERE. Try the brake booster tests.

[Haficon]

Thanks a lot... Gonna read up on this and do some trouble shooting... I am trying to sell the truck would be nice if it had breaks...

[Haficon]

So, I checked a few things and everything seems to be working correctly. Bled the breaks again and the pedal came back for about 1 minute and fell back off. I knew the rear brakes need to be replaced they were seized up, I have not been able to find any leaks in the hydraulic side. 

 

But a 2nd question the steel line and been pieced and parted together, I am considering replacing it all with braided stainless steel hose. Anyone take a shot at this before? I know the line will hold the pressure no problem, getting the ends for the hose to connect to the portioning valve and brake side should not be to difficult we have a fully equipped hose shop were we can build almost anything.