All new brakes w/ Tundra fronts, pedal is still spongy

[octanejunkie]

Try bleeding with the engine running.....

I bled my 2WD 99 sport with the engine running otherwise I couldn't get a good pedal feel.

While logic says this should not be necessary, there is no vacuum to the booster otherwise and ABS doesn't operate without at least ECU power.

That was my experience, although others have not needed the vehicle running to get a good bleed.

 

[absalom]

Have you done the whole pump pedal 40 times with ignition off? This is necessary to purge the brake booster prior to bleeding. To be honest, these trucks are a PITA to bleed, and it's a combo of everything already mentioned and just repeatedly bleeding over time to get it right.

Or just pony up $50 for a power bleeder and be done with it.

 

[SeaBass5000x]

Using this site, I did the Tundra upgrade and tightened my rear brakes/parking brake this summer on my 99' SR5 manual transmission. I had the same outcome of everything turning out great but the brake pedal sank very low before engaging the brakes, and they were somewhat squishy. I bled, bled again, bled following the pattern, bled with the engine running, bled using different pedal pushing techniques, installed speed bleeders and did it all again. Each time I found a bubble or two and very minor improvements to the brake pedal. I was about to start diving into master cylinder replacement, braided brakes lines, etc. when I found somewhere on this site someone instructed to take the rig out on dirt roads and really engage the ABS multiple times, then bleed again. I did this skeptically but it produced an amazing amount of bubbles during the bleed. I actually took it to the dirt roads twice, and both rounds produced bubbles. My brake pedal became much more firm each time. After the second time the brake pedal was firm and felt great, and been solid since.

Hope this helps!
(I've been lurking/using this sight to do about 50 things to my rig for the past 5 years, but this is my first post, largely due to the fact that this is the first time I felt like I had something useful to add.)

 

[GhostRing]

I have a '98 with the big TBU and the ABS fuse removed and have that spongy pedal feel.
Will I still be able to effectively bleed the brakes in this condition?
If the above post is correct, should I bleed with the ABS still functioning
and then re-remove the fuse (I know the mixed response to disabling ABS)

 

[SeaBass5000x]

GhostRing, I'm most definitely not an expert on this, but FWIW when I did mine I did not disable the ABS at all. I wish I could find the thread where I got the most detailed instructions on engaging the ABS for bleeding after the TUB. Probably important to note that I put on the smaller Tundra brakes (193s, if memory serves).

To the OP, I did find this in my notes which is from another thread that quotes the FSM regarding the 40 brake pumps mentioned above:

Try this for bleeding the brake booster before bleeding the brakes:

(a) Turn the ignition switch OFF, depress the brake pedal
more than 40 times.
HINT:
When a pressure in power supply system is released, reaction
force becomes heavy and stroke becomes shorter.
(b) Turn the ignition switch ON, check that the pump stops after
approx. 30 to 40 sec.
NOTICE:
When the pump does not stop, repeat step (a) and (b) again.
(c) With the ignition switch remained ON, depress the brake
pedal more than 20 times.
(d) Observe the procedure in step 4 and bleed the right and
left front brake caliper.
(e) Holding the brake pedal depressed, bleed the right and
left rear brake caliper.
HINT:
It is not necessary to depress the pedal continuously, as brake
fluid flows out by first depressing.

Then bleed as normal:
(a) Connect the vinyl tube to the brake caliper.
(b) Depress the brake pedal several times, then loosen the
bleeder plug with the pedal held down.
(c) At the point when fluid stops coming out, tighten the
bleeder plug, then release the brake pedal.
(d) Repeat (b) and (c) until all the air in the fluid has been bled
out.
(e) Repeat the above procedure to bleed the brake line for
each wheel.

 

[thecole1098]

GhostRing, I'm most definitely not an expert on this, but FWIW when I did mine I did not disable the ABS at all. I wish I could find the thread where I got the most detailed instructions on engaging the ABS for bleeding after the TUB. Probably important to note that I put on the smaller Tundra brakes (193s, if memory serves).

To the OP, I did find this in my notes which is from another thread that quotes the FSM regarding the 40 brake pumps mentioned above:

Try this for bleeding the brake booster before bleeding the brakes:

(a) Turn the ignition switch OFF, depress the brake pedal
more than 40 times.
HINT:
When a pressure in power supply system is released, reaction
force becomes heavy and stroke becomes shorter.
(b) Turn the ignition switch ON, check that the pump stops after
approx. 30 to 40 sec.
NOTICE:
When the pump does not stop, repeat step (a) and (b) again.
(c) With the ignition switch remained ON, depress the brake
pedal more than 20 times.
(d) Observe the procedure in step 4 and bleed the right and
left front brake caliper.
(e) Holding the brake pedal depressed, bleed the right and
left rear brake caliper.
HINT:
It is not necessary to depress the pedal continuously, as brake
fluid flows out by first depressing.

Then bleed as normal:
(a) Connect the vinyl tube to the brake caliper.
(b) Depress the brake pedal several times, then loosen the
bleeder plug with the pedal held down.
(c) At the point when fluid stops coming out, tighten the
bleeder plug, then release the brake pedal.
(d) Repeat (b) and (c) until all the air in the fluid has been bled
out.
(e) Repeat the above procedure to bleed the brake line for
each wheel.

Those instructions only apply to the 01 and 02 4runners that have the hydraulic brake system. The older 3rd gens used traditional vacuum boosters with a separate ABS unit not integrated into the master cylinder.