I've been leaving my 92 F-150 sit too much and when I got in it last weekend the brake went almost all the way to the floor.

The brake fluid reservoir level has not changed. Vacuum at the master cylinder seems good.

Anyone had this problem or know what to look for?

 

provide more details... did the problem repeat or was it a one-time thing? Did you have brakes or not? Do you mean that vacuum at the booster was good? It wouldn't be a vacuum issue... that would make the brake pedal hard, not soft.

from your very brief description, it sounds like maybe you blew a brake line. It it broke on that apply the brake fluid reservoir would still be full. It would take several applies to pump out enough fluid to see a difference.

Pump the brake pedal 5-10 times and then get out and look for where the brake fluid is coming from. If its a broken line you'll see the fluid.

 

It could be an easy bleed job or it could be a booster. I would start by bleeding the brakes. If they are that old chances are the bleeder valve will sheer off and you will have to pick up some new wheel cylinders and calipers.

 

Itcould also be your brake master cylinder. Try pumping the pedal, if it works better it's probably the problem.

 

Well I flushed/bled out the old fluid. Had quite a bit of air in the system. The brake pedal and brakes feel normal now.

Thanks to all for the advice.

 

Good to hear! Brake fluid loses viscosity after awhile just the same as oil. Some people think the stuff last's forever, and antifreeze too. These are all regular maintnence items that are often overlooked. Good job fixing it yourself!