Brand new Hydroboost unit pedal pushing back

[xm20k]

Ok so I just installed this hydro unit from CPP. Jacked up the front end and cranked the wheel lock to lock about 5 times and then pumped the pedal 3-5 times and repeated this about 5-6 times to bleed it. Fired it up and proceeded to do it a few more times while running. The pedal is stiff at the start of travel as if it takes a second to assist than goes to feeling like power brakes like it should, then when I let go it seems to just hang then jumps back up. Power steering feels fine. I'm pretty sure everything is plumbed correctly, maybe not fully bled?

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[bucket]

You didn't have the brake lines undone, correct?

My 79's hydroboost doesn't have much pedal travel at all. It's a very firm pedal and and to apply more brake pressure, you simply push the pedal harder and it stops faster, despite the pedal not really moving.

My '00 Burb, '00 van and '13 van with hydroboost behave more like the typical vacuum brake system.

In short, I don't know how the units actually work, but they must be tunable. Maybe yours is a little screwy, or small amounts of air in the system are giving it fits.

 

[xm20k]

Brake lines were not undone I'm thinking I just didn't get it fully bled. It is firm at first than gets soft and then when I step off of the pedal it hangs for a second than returns fairly firmly.
It also didn't seem to take as much to top of the fluid as I though it should.
I'll run thru it again tomorrow

First Hydro unit I've ever messed with other than driving the F650 at work, I've never had to work on it.

 

[HotWheelsBurban]

Brake lines were not undone I'm thinking I just didn't get it fully bled. It is firm at first than gets soft and then when I step off of the pedal it hangs for a second than returns fairly firmly.
It also didn't seem to take as much to top of the fluid as I though it should.
I'll run thru it again tomorrow

First Hydro unit I've ever messed with other than driving the F650 at work, I've never had to work on it.

You probably need to bleed it some more. The recommended procedure is to turn the wheel lock to lock, like three times, then stomp on the brake pedal twice, hold each time and then release it. My mechanic neighbor and I did this for about 5-6 hours, over two evenings, to get the hydro boost unit and the new master cylinder, bled fully on my OBS one ton Crew Cab. We did this with the front end jacked up enough to get the wheels off the ground, not running, and then a while with it running.
Same here, first one I've had to mess with other than getting it replaced three years ago.

 

[xm20k]

I think I've got it! Ran thru the prosses probably 3 times with a half hour or so in between to let any micro bubbles dissipate from the res, did it again like 3 times with the engine running, did a few test stops back and forth in the driveway then took a quick spin around town and she has brakes holy crap does she have brakes.

Will take a bit to get used too compared to when I was running manual. I think I would have had to stand on it and anchor myself with the wheel to get it to stop as fast as it does now with a tap.

 

[xm20k]

My '00 Burb, '00 van and '13 van with hydroboost behave more like the typical vacuum brake system.

Thats how this one acts. Feels like vacuum with normal braking, but applies more aggressively, but then again that maybe the brakes themselves because I just might not have been able to apply them Wilwood big brakes that hard when they were manual.